25 files changed, 5665 insertions, 0 deletions

diff --git a/src/lisp/.gitignore b/src/lisp/.gitignore
new file mode 100644
index 00000000..76a555ea
--- /dev/null
+++ b/src/lisp/.gitignore
@@ -0,0 +1,2 @@
+ao_lisp_make_const
+ao_lisp_const.h
diff --git a/src/lisp/Makefile b/src/lisp/Makefile
new file mode 100644
index 00000000..25796ec5
--- /dev/null
+++ b/src/lisp/Makefile
@@ -0,0 +1,22 @@
+all: ao_lisp_const.h
+
+clean:
+	rm -f ao_lisp_const.h $(OBJS) ao_lisp_make_const
+
+ao_lisp_const.h: ao_lisp_const.lisp ao_lisp_make_const
+	./ao_lisp_make_const -o $@ ao_lisp_const.lisp
+
+include Makefile-inc
+SRCS=$(LISP_SRCS)
+
+HDRS=$(LISP_HDRS)
+
+OBJS=$(SRCS:.c=.o)
+
+CFLAGS=-DAO_LISP_MAKE_CONST -O0 -g -I. -Wall -Wextra -no-pie
+
+
+ao_lisp_make_const:  $(OBJS)
+	$(CC) $(CFLAGS) -o $@ $(OBJS)
+
+$(OBJS): $(HDRS)
diff --git a/src/lisp/Makefile-inc b/src/lisp/Makefile-inc
new file mode 100644
index 00000000..126deeb0
--- /dev/null
+++ b/src/lisp/Makefile-inc
@@ -0,0 +1,22 @@
+LISP_SRCS=\
+	ao_lisp_make_const.c\
+	ao_lisp_mem.c \
+	ao_lisp_cons.c \
+	ao_lisp_string.c \
+	ao_lisp_atom.c \
+	ao_lisp_int.c \
+	ao_lisp_poly.c \
+	ao_lisp_builtin.c \
+	ao_lisp_read.c \
+	ao_lisp_frame.c \
+	ao_lisp_lambda.c \
+	ao_lisp_eval.c \
+	ao_lisp_rep.c \
+	ao_lisp_save.c \
+	ao_lisp_stack.c \
+	ao_lisp_error.c 
+
+LISP_HDRS=\
+	ao_lisp.h \
+	ao_lisp_os.h \
+	ao_lisp_read.h
diff --git a/src/lisp/Makefile-lisp b/src/lisp/Makefile-lisp
new file mode 100644
index 00000000..998c7673
--- /dev/null
+++ b/src/lisp/Makefile-lisp
@@ -0,0 +1,4 @@
+include ../lisp/Makefile-inc
+
+ao_lisp_const.h: $(LISP_SRCS) $(LISP_HDRS)
+	+cd ../lisp && make $@
diff --git a/src/lisp/ao_lisp.h b/src/lisp/ao_lisp.h
new file mode 100644
index 00000000..980514cc
--- /dev/null
+++ b/src/lisp/ao_lisp.h
@@ -0,0 +1,793 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#ifndef _AO_LISP_H_
+#define _AO_LISP_H_
+
+#define DBG_MEM		0
+#define DBG_EVAL	0
+
+#include <stdint.h>
+#include <string.h>
+#include <ao_lisp_os.h>
+
+typedef uint16_t	ao_poly;
+typedef int16_t		ao_signed_poly;
+
+#ifdef AO_LISP_SAVE
+
+struct ao_lisp_os_save {
+	ao_poly		atoms;
+	ao_poly		globals;
+	uint16_t	const_checksum;
+	uint16_t	const_checksum_inv;
+};
+
+#define AO_LISP_POOL_EXTRA	(sizeof(struct ao_lisp_os_save))
+#define AO_LISP_POOL	((int) (AO_LISP_POOL_TOTAL - AO_LISP_POOL_EXTRA))
+
+int
+ao_lisp_os_save(void);
+
+int
+ao_lisp_os_restore_save(struct ao_lisp_os_save *save, int offset);
+
+int
+ao_lisp_os_restore(void);
+
+#endif
+
+#ifdef AO_LISP_MAKE_CONST
+#define AO_LISP_POOL_CONST	16384
+extern uint8_t ao_lisp_const[AO_LISP_POOL_CONST] __attribute__((aligned(4)));
+#define ao_lisp_pool ao_lisp_const
+#define AO_LISP_POOL AO_LISP_POOL_CONST
+
+#define _atom(n) ao_lisp_atom_poly(ao_lisp_atom_intern(n))
+
+#define _ao_lisp_atom_quote	_atom("quote")
+#define _ao_lisp_atom_set 	_atom("set")
+#define _ao_lisp_atom_setq 	_atom("setq")
+#define _ao_lisp_atom_t 	_atom("t")
+#define _ao_lisp_atom_car 	_atom("car")
+#define _ao_lisp_atom_cdr	_atom("cdr")
+#define _ao_lisp_atom_cons	_atom("cons")
+#define _ao_lisp_atom_last	_atom("last")
+#define _ao_lisp_atom_length	_atom("length")
+#define _ao_lisp_atom_cond	_atom("cond")
+#define _ao_lisp_atom_lambda	_atom("lambda")
+#define _ao_lisp_atom_led	_atom("led")
+#define _ao_lisp_atom_delay	_atom("delay")
+#define _ao_lisp_atom_pack	_atom("pack")
+#define _ao_lisp_atom_unpack	_atom("unpack")
+#define _ao_lisp_atom_flush	_atom("flush")
+#define _ao_lisp_atom_eval	_atom("eval")
+#define _ao_lisp_atom_read	_atom("read")
+#define _ao_lisp_atom_eof	_atom("eof")
+#define _ao_lisp_atom_save	_atom("save")
+#define _ao_lisp_atom_restore	_atom("restore")
+#define _ao_lisp_atom_call2fcc	_atom("call/cc")
+#define _ao_lisp_atom_collect	_atom("collect")
+#define _ao_lisp_atom_symbolp   _atom("symbol?")
+#define _ao_lisp_atom_builtin   _atom("builtin?")
+#define _ao_lisp_atom_symbolp   _atom("symbol?")
+#define _ao_lisp_atom_symbolp   _atom("symbol?")
+#else
+#include "ao_lisp_const.h"
+#ifndef AO_LISP_POOL
+#define AO_LISP_POOL	3072
+#endif
+extern uint8_t		ao_lisp_pool[AO_LISP_POOL + AO_LISP_POOL_EXTRA] __attribute__((aligned(4)));
+#endif
+
+/* Primitive types */
+#define AO_LISP_CONS		0
+#define AO_LISP_INT		1
+#define AO_LISP_STRING		2
+#define AO_LISP_OTHER		3
+
+#define AO_LISP_TYPE_MASK	0x0003
+#define AO_LISP_TYPE_SHIFT	2
+#define AO_LISP_REF_MASK	0x7ffc
+#define AO_LISP_CONST		0x8000
+
+/* These have a type value at the start of the struct */
+#define AO_LISP_ATOM		4
+#define AO_LISP_BUILTIN		5
+#define AO_LISP_FRAME		6
+#define AO_LISP_LAMBDA		7
+#define AO_LISP_STACK		8
+#define AO_LISP_NUM_TYPE	9
+
+/* Leave two bits for types to use as they please */
+#define AO_LISP_OTHER_TYPE_MASK	0x3f
+
+#define AO_LISP_NIL	0
+
+extern uint16_t		ao_lisp_top;
+
+#define AO_LISP_OOM		0x01
+#define AO_LISP_DIVIDE_BY_ZERO	0x02
+#define AO_LISP_INVALID		0x04
+#define AO_LISP_UNDEFINED	0x08
+#define AO_LISP_EOF		0x10
+
+extern uint8_t		ao_lisp_exception;
+
+static inline int
+ao_lisp_is_const(ao_poly poly) {
+	return poly & AO_LISP_CONST;
+}
+
+#define AO_LISP_IS_CONST(a)	(ao_lisp_const <= ((uint8_t *) (a)) && ((uint8_t *) (a)) < ao_lisp_const + AO_LISP_POOL_CONST)
+#define AO_LISP_IS_POOL(a)	(ao_lisp_pool <= ((uint8_t *) (a)) && ((uint8_t *) (a)) < ao_lisp_pool + AO_LISP_POOL)
+#define AO_LISP_IS_INT(p)	(ao_lisp_base_type(p) == AO_LISP_INT);
+
+void *
+ao_lisp_ref(ao_poly poly);
+
+ao_poly
+ao_lisp_poly(const void *addr, ao_poly type);
+
+struct ao_lisp_type {
+	int	(*size)(void *addr);
+	void	(*mark)(void *addr);
+	void	(*move)(void *addr);
+	char	name[];
+};
+
+struct ao_lisp_cons {
+	ao_poly		car;
+	ao_poly		cdr;
+};
+
+struct ao_lisp_atom {
+	uint8_t		type;
+	uint8_t		pad[1];
+	ao_poly		next;
+	char		name[];
+};
+
+struct ao_lisp_val {
+	ao_poly		atom;
+	ao_poly		val;
+};
+
+struct ao_lisp_frame {
+	uint8_t			type;
+	uint8_t			num;
+	ao_poly			prev;
+	struct ao_lisp_val	vals[];
+};
+
+/* Set on type when the frame escapes the lambda */
+#define AO_LISP_FRAME_MARK	0x80
+#define AO_LISP_FRAME_PRINT	0x40
+
+static inline int ao_lisp_frame_marked(struct ao_lisp_frame *f) {
+	return f->type & AO_LISP_FRAME_MARK;
+}
+
+static inline struct ao_lisp_frame *
+ao_lisp_poly_frame(ao_poly poly) {
+	return ao_lisp_ref(poly);
+}
+
+static inline ao_poly
+ao_lisp_frame_poly(struct ao_lisp_frame *frame) {
+	return ao_lisp_poly(frame, AO_LISP_OTHER);
+}
+
+enum eval_state {
+	eval_sexpr,		/* Evaluate an sexpr */
+	eval_val,		/* Value computed */
+	eval_formal,		/* Formal computed */
+	eval_exec,		/* Start a lambda evaluation */
+	eval_cond,		/* Start next cond clause */
+	eval_cond_test,		/* Check cond condition */
+	eval_progn,		/* Start next progn entry */
+	eval_while,		/* Start while condition */
+	eval_while_test,	/* Check while condition */
+	eval_macro,		/* Finished with macro generation */
+};
+
+struct ao_lisp_stack {
+	uint8_t			type;		/* AO_LISP_STACK */
+	uint8_t			state;		/* enum eval_state */
+	ao_poly			prev;		/* previous stack frame */
+	ao_poly			sexprs;		/* expressions to evaluate */
+	ao_poly			values;		/* values computed */
+	ao_poly			values_tail;	/* end of the values list for easy appending */
+	ao_poly			frame;		/* current lookup frame */
+	ao_poly			list;		/* most recent function call */
+};
+
+#define AO_LISP_STACK_MARK	0x80	/* set on type when a reference has been taken */
+#define AO_LISP_STACK_PRINT	0x40	/* stack is being printed */
+
+static inline int ao_lisp_stack_marked(struct ao_lisp_stack *s) {
+	return s->type & AO_LISP_STACK_MARK;
+}
+
+static inline void ao_lisp_stack_mark(struct ao_lisp_stack *s) {
+	s->type |= AO_LISP_STACK_MARK;
+}
+
+static inline struct ao_lisp_stack *
+ao_lisp_poly_stack(ao_poly p)
+{
+	return ao_lisp_ref(p);
+}
+
+static inline ao_poly
+ao_lisp_stack_poly(struct ao_lisp_stack *stack)
+{
+	return ao_lisp_poly(stack, AO_LISP_OTHER);
+}
+
+extern ao_poly			ao_lisp_v;
+
+#define AO_LISP_FUNC_LAMBDA	0
+#define AO_LISP_FUNC_NLAMBDA	1
+#define AO_LISP_FUNC_MACRO	2
+#define AO_LISP_FUNC_LEXPR	3
+
+#define AO_LISP_FUNC_FREE_ARGS	0x80
+#define AO_LISP_FUNC_MASK	0x7f
+
+#define AO_LISP_FUNC_F_LAMBDA	(AO_LISP_FUNC_FREE_ARGS | AO_LISP_FUNC_LAMBDA)
+#define AO_LISP_FUNC_F_NLAMBDA	(AO_LISP_FUNC_FREE_ARGS | AO_LISP_FUNC_NLAMBDA)
+#define AO_LISP_FUNC_F_MACRO	(AO_LISP_FUNC_FREE_ARGS | AO_LISP_FUNC_MACRO)
+#define AO_LISP_FUNC_F_LEXPR	(AO_LISP_FUNC_FREE_ARGS | AO_LISP_FUNC_LEXPR)
+
+struct ao_lisp_builtin {
+	uint8_t		type;
+	uint8_t		args;
+	uint16_t	func;
+};
+
+enum ao_lisp_builtin_id {
+	builtin_eval,
+	builtin_read,
+	builtin_lambda,
+	builtin_lexpr,
+	builtin_nlambda,
+	builtin_macro,
+	builtin_car,
+	builtin_cdr,
+	builtin_cons,
+	builtin_last,
+	builtin_length,
+	builtin_quote,
+	builtin_set,
+	builtin_setq,
+	builtin_cond,
+	builtin_progn,
+	builtin_while,
+	builtin_print,
+	builtin_patom,
+	builtin_plus,
+	builtin_minus,
+	builtin_times,
+	builtin_divide,
+	builtin_mod,
+	builtin_equal,
+	builtin_less,
+	builtin_greater,
+	builtin_less_equal,
+	builtin_greater_equal,
+	builtin_pack,
+	builtin_unpack,
+	builtin_flush,
+	builtin_delay,
+	builtin_led,
+	builtin_save,
+	builtin_restore,
+	builtin_call_cc,
+	builtin_collect,
+	_builtin_last
+};
+
+typedef ao_poly (*ao_lisp_func_t)(struct ao_lisp_cons *cons);
+
+extern const ao_lisp_func_t	ao_lisp_builtins[];
+
+static inline ao_lisp_func_t
+ao_lisp_func(struct ao_lisp_builtin *b)
+{
+	return ao_lisp_builtins[b->func];
+}
+
+struct ao_lisp_lambda {
+	uint8_t		type;
+	uint8_t		args;
+	ao_poly		code;
+	ao_poly		frame;
+};
+
+static inline struct ao_lisp_lambda *
+ao_lisp_poly_lambda(ao_poly poly)
+{
+	return ao_lisp_ref(poly);
+}
+
+static inline ao_poly
+ao_lisp_lambda_poly(struct ao_lisp_lambda *lambda)
+{
+	return ao_lisp_poly(lambda, AO_LISP_OTHER);
+}
+
+static inline void *
+ao_lisp_poly_other(ao_poly poly) {
+	return ao_lisp_ref(poly);
+}
+
+static inline uint8_t
+ao_lisp_other_type(void *other) {
+#if DBG_MEM
+	if ((*((uint8_t *) other) & AO_LISP_OTHER_TYPE_MASK) >= AO_LISP_NUM_TYPE)
+		ao_lisp_abort();
+#endif
+	return *((uint8_t *) other) & AO_LISP_OTHER_TYPE_MASK;
+}
+
+static inline ao_poly
+ao_lisp_other_poly(const void *other)
+{
+	return ao_lisp_poly(other, AO_LISP_OTHER);
+}
+
+static inline int
+ao_lisp_size_round(int size)
+{
+	return (size + 3) & ~3;
+}
+
+static inline int
+ao_lisp_size(const struct ao_lisp_type *type, void *addr)
+{
+	return ao_lisp_size_round(type->size(addr));
+}
+
+#define AO_LISP_OTHER_POLY(other) ((ao_poly)(other) + AO_LISP_OTHER)
+
+static inline int ao_lisp_poly_base_type(ao_poly poly) {
+	return poly & AO_LISP_TYPE_MASK;
+}
+
+static inline int ao_lisp_poly_type(ao_poly poly) {
+	int	type = poly & AO_LISP_TYPE_MASK;
+	if (type == AO_LISP_OTHER)
+		return ao_lisp_other_type(ao_lisp_poly_other(poly));
+	return type;
+}
+
+static inline struct ao_lisp_cons *
+ao_lisp_poly_cons(ao_poly poly)
+{
+	return ao_lisp_ref(poly);
+}
+
+static inline ao_poly
+ao_lisp_cons_poly(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_poly(cons, AO_LISP_CONS);
+}
+
+static inline int
+ao_lisp_poly_int(ao_poly poly)
+{
+	return (int) ((ao_signed_poly) poly >> AO_LISP_TYPE_SHIFT);
+}
+
+static inline ao_poly
+ao_lisp_int_poly(int i)
+{
+	return ((ao_poly) i << 2) | AO_LISP_INT;
+}
+
+static inline char *
+ao_lisp_poly_string(ao_poly poly)
+{
+	return ao_lisp_ref(poly);
+}
+
+static inline ao_poly
+ao_lisp_string_poly(char *s)
+{
+	return ao_lisp_poly(s, AO_LISP_STRING);
+}
+
+static inline struct ao_lisp_atom *
+ao_lisp_poly_atom(ao_poly poly)
+{
+	return ao_lisp_ref(poly);
+}
+
+static inline ao_poly
+ao_lisp_atom_poly(struct ao_lisp_atom *a)
+{
+	return ao_lisp_poly(a, AO_LISP_OTHER);
+}
+
+static inline struct ao_lisp_builtin *
+ao_lisp_poly_builtin(ao_poly poly)
+{
+	return ao_lisp_ref(poly);
+}
+
+static inline ao_poly
+ao_lisp_builtin_poly(struct ao_lisp_builtin *b)
+{
+	return ao_lisp_poly(b, AO_LISP_OTHER);
+}
+
+/* memory functions */
+
+extern int ao_lisp_collects[2];
+extern int ao_lisp_freed[2];
+extern int ao_lisp_loops[2];
+
+/* returns 1 if the object was already marked */
+int
+ao_lisp_mark(const struct ao_lisp_type *type, void *addr);
+
+/* returns 1 if the object was already marked */
+int
+ao_lisp_mark_memory(const struct ao_lisp_type *type, void *addr);
+
+void *
+ao_lisp_move_map(void *addr);
+
+/* returns 1 if the object was already moved */
+int
+ao_lisp_move(const struct ao_lisp_type *type, void **ref);
+
+/* returns 1 if the object was already moved */
+int
+ao_lisp_move_memory(const struct ao_lisp_type *type, void **ref);
+
+void *
+ao_lisp_alloc(int size);
+
+#define AO_LISP_COLLECT_FULL		1
+#define AO_LISP_COLLECT_INCREMENTAL	0
+
+int
+ao_lisp_collect(uint8_t style);
+
+void
+ao_lisp_cons_stash(int id, struct ao_lisp_cons *cons);
+
+struct ao_lisp_cons *
+ao_lisp_cons_fetch(int id);
+
+void
+ao_lisp_poly_stash(int id, ao_poly poly);
+
+ao_poly
+ao_lisp_poly_fetch(int id);
+
+void
+ao_lisp_string_stash(int id, char *string);
+
+char *
+ao_lisp_string_fetch(int id);
+
+static inline void
+ao_lisp_stack_stash(int id, struct ao_lisp_stack *stack) {
+	ao_lisp_poly_stash(id, ao_lisp_stack_poly(stack));
+}
+
+static inline struct ao_lisp_stack *
+ao_lisp_stack_fetch(int id) {
+	return ao_lisp_poly_stack(ao_lisp_poly_fetch(id));
+}
+
+/* cons */
+extern const struct ao_lisp_type ao_lisp_cons_type;
+
+struct ao_lisp_cons *
+ao_lisp_cons_cons(ao_poly car, struct ao_lisp_cons *cdr);
+
+extern struct ao_lisp_cons *ao_lisp_cons_free_list;
+
+void
+ao_lisp_cons_free(struct ao_lisp_cons *cons);
+
+void
+ao_lisp_cons_print(ao_poly);
+
+void
+ao_lisp_cons_patom(ao_poly);
+
+int
+ao_lisp_cons_length(struct ao_lisp_cons *cons);
+
+/* string */
+extern const struct ao_lisp_type ao_lisp_string_type;
+
+char *
+ao_lisp_string_copy(char *a);
+
+char *
+ao_lisp_string_cat(char *a, char *b);
+
+ao_poly
+ao_lisp_string_pack(struct ao_lisp_cons *cons);
+
+ao_poly
+ao_lisp_string_unpack(char *a);
+
+void
+ao_lisp_string_print(ao_poly s);
+
+void
+ao_lisp_string_patom(ao_poly s);
+
+/* atom */
+extern const struct ao_lisp_type ao_lisp_atom_type;
+
+extern struct ao_lisp_atom	*ao_lisp_atoms;
+extern struct ao_lisp_frame	*ao_lisp_frame_global;
+extern struct ao_lisp_frame	*ao_lisp_frame_current;
+
+void
+ao_lisp_atom_print(ao_poly a);
+
+struct ao_lisp_atom *
+ao_lisp_atom_intern(char *name);
+
+ao_poly *
+ao_lisp_atom_ref(struct ao_lisp_frame *frame, ao_poly atom);
+
+ao_poly
+ao_lisp_atom_get(ao_poly atom);
+
+ao_poly
+ao_lisp_atom_set(ao_poly atom, ao_poly val);
+
+/* int */
+void
+ao_lisp_int_print(ao_poly i);
+
+/* prim */
+void
+ao_lisp_poly_print(ao_poly p);
+
+void
+ao_lisp_poly_patom(ao_poly p);
+
+int
+ao_lisp_poly_mark(ao_poly p, uint8_t note_cons);
+
+/* returns 1 if the object has already been moved */
+int
+ao_lisp_poly_move(ao_poly *p, uint8_t note_cons);
+
+/* eval */
+
+void
+ao_lisp_eval_clear_globals(void);
+
+int
+ao_lisp_eval_restart(void);
+
+ao_poly
+ao_lisp_eval(ao_poly p);
+
+ao_poly
+ao_lisp_set_cond(struct ao_lisp_cons *cons);
+
+/* builtin */
+void
+ao_lisp_builtin_print(ao_poly b);
+
+extern const struct ao_lisp_type ao_lisp_builtin_type;
+
+/* Check argument count */
+ao_poly
+ao_lisp_check_argc(ao_poly name, struct ao_lisp_cons *cons, int min, int max);
+
+/* Check argument type */
+ao_poly
+ao_lisp_check_argt(ao_poly name, struct ao_lisp_cons *cons, int argc, int type, int nil_ok);
+
+/* Fetch an arg (nil if off the end) */
+ao_poly
+ao_lisp_arg(struct ao_lisp_cons *cons, int argc);
+
+char *
+ao_lisp_args_name(uint8_t args);
+
+/* read */
+extern struct ao_lisp_cons	*ao_lisp_read_cons;
+extern struct ao_lisp_cons	*ao_lisp_read_cons_tail;
+extern struct ao_lisp_cons	*ao_lisp_read_stack;
+
+ao_poly
+ao_lisp_read(void);
+
+/* rep */
+ao_poly
+ao_lisp_read_eval_print(void);
+
+/* frame */
+extern const struct ao_lisp_type ao_lisp_frame_type;
+
+#define AO_LISP_FRAME_FREE	6
+
+extern struct ao_lisp_frame	*ao_lisp_frame_free_list[AO_LISP_FRAME_FREE];
+
+ao_poly
+ao_lisp_frame_mark(struct ao_lisp_frame *frame);
+
+ao_poly *
+ao_lisp_frame_ref(struct ao_lisp_frame *frame, ao_poly atom);
+
+struct ao_lisp_frame *
+ao_lisp_frame_new(int num);
+
+void
+ao_lisp_frame_free(struct ao_lisp_frame *frame);
+
+void
+ao_lisp_frame_bind(struct ao_lisp_frame *frame, int num, ao_poly atom, ao_poly val);
+
+int
+ao_lisp_frame_add(struct ao_lisp_frame **frame, ao_poly atom, ao_poly val);
+
+void
+ao_lisp_frame_print(ao_poly p);
+
+/* lambda */
+extern const struct ao_lisp_type ao_lisp_lambda_type;
+
+extern const char *ao_lisp_state_names[];
+
+struct ao_lisp_lambda *
+ao_lisp_lambda_new(ao_poly cons);
+
+void
+ao_lisp_lambda_print(ao_poly lambda);
+
+ao_poly
+ao_lisp_lambda(struct ao_lisp_cons *cons);
+
+ao_poly
+ao_lisp_lexpr(struct ao_lisp_cons *cons);
+
+ao_poly
+ao_lisp_nlambda(struct ao_lisp_cons *cons);
+
+ao_poly
+ao_lisp_macro(struct ao_lisp_cons *cons);
+
+ao_poly
+ao_lisp_lambda_eval(void);
+
+/* save */
+
+ao_poly
+ao_lisp_save(struct ao_lisp_cons *cons);
+
+ao_poly
+ao_lisp_restore(struct ao_lisp_cons *cons);
+
+/* stack */
+
+extern const struct ao_lisp_type ao_lisp_stack_type;
+extern struct ao_lisp_stack	*ao_lisp_stack;
+extern struct ao_lisp_stack	*ao_lisp_stack_free_list;
+
+void
+ao_lisp_stack_reset(struct ao_lisp_stack *stack);
+
+int
+ao_lisp_stack_push(void);
+
+void
+ao_lisp_stack_pop(void);
+
+void
+ao_lisp_stack_clear(void);
+
+void
+ao_lisp_stack_print(ao_poly stack);
+
+ao_poly
+ao_lisp_stack_eval(void);
+
+ao_poly
+ao_lisp_call_cc(struct ao_lisp_cons *cons);
+
+/* error */
+
+void
+ao_lisp_error_poly(char *name, ao_poly poly, ao_poly last);
+
+void
+ao_lisp_error_frame(int indent, char *name, struct ao_lisp_frame *frame);
+
+ao_poly
+ao_lisp_error(int error, char *format, ...);
+
+/* debugging macros */
+
+#if DBG_EVAL
+#define DBG_CODE	1
+int ao_lisp_stack_depth;
+#define DBG_DO(a)	a
+#define DBG_INDENT()	do { int _s; for(_s = 0; _s < ao_lisp_stack_depth; _s++) printf("  "); } while(0)
+#define DBG_IN()	(++ao_lisp_stack_depth)
+#define DBG_OUT()	(--ao_lisp_stack_depth)
+#define DBG_RESET()	(ao_lisp_stack_depth = 0)
+#define DBG(...) 	printf(__VA_ARGS__)
+#define DBGI(...)	do { DBG("%4d: ", __LINE__); DBG_INDENT(); DBG(__VA_ARGS__); } while (0)
+#define DBG_CONS(a)	ao_lisp_cons_print(ao_lisp_cons_poly(a))
+#define DBG_POLY(a)	ao_lisp_poly_print(a)
+#define OFFSET(a)	((a) ? (int) ((uint8_t *) a - ao_lisp_pool) : -1)
+#define DBG_STACK()	ao_lisp_stack_print(ao_lisp_stack_poly(ao_lisp_stack))
+static inline void
+ao_lisp_frames_dump(void)
+{
+	struct ao_lisp_stack *s;
+	DBGI(".. current frame: "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+	for (s = ao_lisp_stack; s; s = ao_lisp_poly_stack(s->prev)) {
+		DBGI(".. stack frame: "); DBG_POLY(s->frame); DBG("\n");
+	}
+}
+#define DBG_FRAMES()	ao_lisp_frames_dump()
+#else
+#define DBG_DO(a)
+#define DBG_INDENT()
+#define DBG_IN()
+#define DBG_OUT()
+#define DBG(...)
+#define DBGI(...)
+#define DBG_CONS(a)
+#define DBG_POLY(a)
+#define DBG_RESET()
+#define DBG_STACK()
+#define DBG_FRAMES()
+#endif
+
+#define DBG_MEM_START	1
+
+#if DBG_MEM
+
+#include <assert.h>
+extern int dbg_move_depth;
+#define MDBG_DUMP 1
+#define MDBG_OFFSET(a)	((int) ((uint8_t *) (a) - ao_lisp_pool))
+
+extern int dbg_mem;
+
+#define MDBG_DO(a)	a
+#define MDBG_MOVE(...) do { if (dbg_mem) { int d; for (d = 0; d < dbg_move_depth; d++) printf ("  "); printf(__VA_ARGS__); } } while (0)
+#define MDBG_MORE(...) do { if (dbg_mem) printf(__VA_ARGS__); } while (0)
+#define MDBG_MOVE_IN()	(dbg_move_depth++)
+#define MDBG_MOVE_OUT()	(assert(--dbg_move_depth >= 0))
+
+#else
+
+#define MDBG_DO(a)
+#define MDBG_MOVE(...)
+#define MDBG_MORE(...)
+#define MDBG_MOVE_IN()
+#define MDBG_MOVE_OUT()
+
+#endif
+
+#endif /* _AO_LISP_H_ */
diff --git a/src/lisp/ao_lisp_atom.c b/src/lisp/ao_lisp_atom.c
new file mode 100644
index 00000000..8c9e8ed1
--- /dev/null
+++ b/src/lisp/ao_lisp_atom.c
@@ -0,0 +1,165 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "ao_lisp.h"
+
+static int name_size(char *name)
+{
+	return sizeof(struct ao_lisp_atom) + strlen(name) + 1;
+}
+
+static int atom_size(void *addr)
+{
+	struct ao_lisp_atom	*atom = addr;
+	if (!atom)
+		return 0;
+	return name_size(atom->name);
+}
+
+static void atom_mark(void *addr)
+{
+	struct ao_lisp_atom	*atom = addr;
+
+	for (;;) {
+		atom = ao_lisp_poly_atom(atom->next);
+		if (!atom)
+			break;
+		if (ao_lisp_mark_memory(&ao_lisp_atom_type, atom))
+			break;
+	}
+}
+
+static void atom_move(void *addr)
+{
+	struct ao_lisp_atom	*atom = addr;
+	int			ret;
+
+	for (;;) {
+		struct ao_lisp_atom *next = ao_lisp_poly_atom(atom->next);
+
+		if (!next)
+			break;
+		ret = ao_lisp_move_memory(&ao_lisp_atom_type, (void **) &next);
+		if (next != ao_lisp_poly_atom(atom->next))
+			atom->next = ao_lisp_atom_poly(next);
+		if (ret)
+			break;
+		atom = next;
+	}
+}
+
+const struct ao_lisp_type ao_lisp_atom_type = {
+	.mark = atom_mark,
+	.size = atom_size,
+	.move = atom_move,
+	.name = "atom"
+};
+
+struct ao_lisp_atom	*ao_lisp_atoms;
+
+struct ao_lisp_atom *
+ao_lisp_atom_intern(char *name)
+{
+	struct ao_lisp_atom	*atom;
+
+	for (atom = ao_lisp_atoms; atom; atom = ao_lisp_poly_atom(atom->next)) {
+		if (!strcmp(atom->name, name))
+			return atom;
+	}
+#ifdef ao_builtin_atoms
+	for (atom = ao_lisp_poly_atom(ao_builtin_atoms); atom; atom = ao_lisp_poly_atom(atom->next)) {
+		if (!strcmp(atom->name, name))
+			return atom;
+	}
+#endif
+	ao_lisp_string_stash(0, name);
+	atom = ao_lisp_alloc(name_size(name));
+	name = ao_lisp_string_fetch(0);
+	if (atom) {
+		atom->type = AO_LISP_ATOM;
+		atom->next = ao_lisp_atom_poly(ao_lisp_atoms);
+		ao_lisp_atoms = atom;
+		strcpy(atom->name, name);
+	}
+	return atom;
+}
+
+struct ao_lisp_frame	*ao_lisp_frame_global;
+struct ao_lisp_frame	*ao_lisp_frame_current;
+
+static void
+ao_lisp_atom_init(void)
+{
+	if (!ao_lisp_frame_global)
+		ao_lisp_frame_global = ao_lisp_frame_new(0);
+}
+
+ao_poly *
+ao_lisp_atom_ref(struct ao_lisp_frame *frame, ao_poly atom)
+{
+	ao_poly	*ref;
+	ao_lisp_atom_init();
+	while (frame) {
+		ref = ao_lisp_frame_ref(frame, atom);
+		if (ref)
+			return ref;
+		frame = ao_lisp_poly_frame(frame->prev);
+	}
+	if (ao_lisp_frame_global) {
+		ref = ao_lisp_frame_ref(ao_lisp_frame_global, atom);
+		if (ref)
+			return ref;
+	}
+	return NULL;
+}
+
+ao_poly
+ao_lisp_atom_get(ao_poly atom)
+{
+	ao_poly *ref = ao_lisp_atom_ref(ao_lisp_frame_current, atom);
+
+	if (!ref && ao_lisp_frame_global)
+		ref = ao_lisp_frame_ref(ao_lisp_frame_global, atom);
+#ifdef ao_builtin_frame
+	if (!ref)
+		ref = ao_lisp_frame_ref(ao_lisp_poly_frame(ao_builtin_frame), atom);
+#endif
+	if (ref)
+		return *ref;
+	return ao_lisp_error(AO_LISP_UNDEFINED, "undefined atom %s", ao_lisp_poly_atom(atom)->name);
+}
+
+ao_poly
+ao_lisp_atom_set(ao_poly atom, ao_poly val)
+{
+	ao_poly *ref = ao_lisp_atom_ref(ao_lisp_frame_current, atom);
+
+	if (!ref && ao_lisp_frame_global)
+		ref = ao_lisp_frame_ref(ao_lisp_frame_global, atom);
+	if (ref)
+		*ref = val;
+	else
+		ao_lisp_frame_add(&ao_lisp_frame_global, atom, val);
+	return val;
+}
+
+void
+ao_lisp_atom_print(ao_poly a)
+{
+	struct ao_lisp_atom *atom = ao_lisp_poly_atom(a);
+	printf("%s", atom->name);
+}
diff --git a/src/lisp/ao_lisp_builtin.c b/src/lisp/ao_lisp_builtin.c
new file mode 100644
index 00000000..902f60e2
--- /dev/null
+++ b/src/lisp/ao_lisp_builtin.c
@@ -0,0 +1,619 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
+static int
+builtin_size(void *addr)
+{
+	(void) addr;
+	return sizeof (struct ao_lisp_builtin);
+}
+
+static void
+builtin_mark(void *addr)
+{
+	(void) addr;
+}
+
+static void
+builtin_move(void *addr)
+{
+	(void) addr;
+}
+
+const struct ao_lisp_type ao_lisp_builtin_type = {
+	.size = builtin_size,
+	.mark = builtin_mark,
+	.move = builtin_move
+};
+
+#ifdef AO_LISP_MAKE_CONST
+char *ao_lisp_builtin_name(enum ao_lisp_builtin_id b) {
+	(void) b;
+	return "???";
+}
+char *ao_lisp_args_name(uint8_t args) {
+	(void) args;
+	return "???";
+}
+#else
+static const ao_poly builtin_names[] = {
+	[builtin_eval] = _ao_lisp_atom_eval,
+	[builtin_read] = _ao_lisp_atom_read,
+	[builtin_lambda] = _ao_lisp_atom_lambda,
+	[builtin_lexpr] = _ao_lisp_atom_lexpr,
+	[builtin_nlambda] = _ao_lisp_atom_nlambda,
+	[builtin_macro] = _ao_lisp_atom_macro,
+	[builtin_car] = _ao_lisp_atom_car,
+	[builtin_cdr] = _ao_lisp_atom_cdr,
+	[builtin_cons] = _ao_lisp_atom_cons,
+	[builtin_last] = _ao_lisp_atom_last,
+	[builtin_length] = _ao_lisp_atom_length,
+	[builtin_quote] = _ao_lisp_atom_quote,
+	[builtin_set] = _ao_lisp_atom_set,
+	[builtin_setq] = _ao_lisp_atom_setq,
+	[builtin_cond] = _ao_lisp_atom_cond,
+	[builtin_progn] = _ao_lisp_atom_progn,
+	[builtin_while] = _ao_lisp_atom_while,
+	[builtin_print] = _ao_lisp_atom_print,
+	[builtin_patom] = _ao_lisp_atom_patom,
+	[builtin_plus] = _ao_lisp_atom_2b,
+	[builtin_minus] = _ao_lisp_atom_2d,
+	[builtin_times] = _ao_lisp_atom_2a,
+	[builtin_divide] = _ao_lisp_atom_2f,
+	[builtin_mod] = _ao_lisp_atom_25,
+	[builtin_equal] = _ao_lisp_atom_3d,
+	[builtin_less] = _ao_lisp_atom_3c,
+	[builtin_greater] = _ao_lisp_atom_3e,
+	[builtin_less_equal] = _ao_lisp_atom_3c3d,
+	[builtin_greater_equal] = _ao_lisp_atom_3e3d,
+	[builtin_pack] = _ao_lisp_atom_pack,
+	[builtin_unpack] = _ao_lisp_atom_unpack,
+	[builtin_flush] = _ao_lisp_atom_flush,
+	[builtin_delay] = _ao_lisp_atom_delay,
+	[builtin_led] = _ao_lisp_atom_led,
+	[builtin_save] = _ao_lisp_atom_save,
+	[builtin_restore] = _ao_lisp_atom_restore,
+	[builtin_call_cc] = _ao_lisp_atom_call2fcc,
+	[builtin_collect] = _ao_lisp_atom_collect,
+#if 0
+	[builtin_symbolp] = _ao_lisp_atom_symbolp,
+	[builtin_listp] = _ao_lisp_atom_listp,
+	[builtin_stringp] = _ao_lisp_atom_stringp,
+	[builtin_numberp] = _ao_lisp_atom_numberp,
+#endif
+};
+
+static char *
+ao_lisp_builtin_name(enum ao_lisp_builtin_id b) {
+	if (b < _builtin_last)
+		return ao_lisp_poly_atom(builtin_names[b])->name;
+	return "???";
+}
+
+static const ao_poly ao_lisp_args_atoms[] = {
+	[AO_LISP_FUNC_LAMBDA] = _ao_lisp_atom_lambda,
+	[AO_LISP_FUNC_LEXPR] = _ao_lisp_atom_lexpr,
+	[AO_LISP_FUNC_NLAMBDA] = _ao_lisp_atom_nlambda,
+	[AO_LISP_FUNC_MACRO] = _ao_lisp_atom_macro,
+};
+
+char *
+ao_lisp_args_name(uint8_t args)
+{
+	args &= AO_LISP_FUNC_MASK;
+	if (args < sizeof ao_lisp_args_atoms / sizeof ao_lisp_args_atoms[0])
+		return ao_lisp_poly_atom(ao_lisp_args_atoms[args])->name;
+	return "(unknown)";
+}
+#endif
+
+void
+ao_lisp_builtin_print(ao_poly b)
+{
+	struct ao_lisp_builtin *builtin = ao_lisp_poly_builtin(b);
+	printf("%s", ao_lisp_builtin_name(builtin->func));
+}
+
+ao_poly
+ao_lisp_check_argc(ao_poly name, struct ao_lisp_cons *cons, int min, int max)
+{
+	int	argc = 0;
+
+	while (cons && argc <= max) {
+		argc++;
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+	if (argc < min || argc > max)
+		return ao_lisp_error(AO_LISP_INVALID, "%s: invalid arg count", ao_lisp_poly_atom(name)->name);
+	return _ao_lisp_atom_t;
+}
+
+ao_poly
+ao_lisp_arg(struct ao_lisp_cons *cons, int argc)
+{
+	if (!cons)
+		return AO_LISP_NIL;
+	while (argc--) {
+		if (!cons)
+			return AO_LISP_NIL;
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+	return cons->car;
+}
+
+ao_poly
+ao_lisp_check_argt(ao_poly name, struct ao_lisp_cons *cons, int argc, int type, int nil_ok)
+{
+	ao_poly car = ao_lisp_arg(cons, argc);
+
+	if ((!car && !nil_ok) || ao_lisp_poly_type(car) != type)
+		return ao_lisp_error(AO_LISP_INVALID, "%s: invalid type for arg %d", ao_lisp_poly_atom(name)->name, argc);
+	return _ao_lisp_atom_t;
+}
+
+ao_poly
+ao_lisp_car(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_car, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_car, cons, 0, AO_LISP_CONS, 0))
+		return AO_LISP_NIL;
+	return ao_lisp_poly_cons(cons->car)->car;
+}
+
+ao_poly
+ao_lisp_cdr(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_cdr, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_cdr, cons, 0, AO_LISP_CONS, 0))
+		return AO_LISP_NIL;
+	return ao_lisp_poly_cons(cons->car)->cdr;
+}
+
+ao_poly
+ao_lisp_cons(struct ao_lisp_cons *cons)
+{
+	ao_poly	car, cdr;
+	if(!ao_lisp_check_argc(_ao_lisp_atom_cons, cons, 2, 2))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_cons, cons, 1, AO_LISP_CONS, 1))
+		return AO_LISP_NIL;
+	car = ao_lisp_arg(cons, 0);
+	cdr = ao_lisp_arg(cons, 1);
+	return ao_lisp_cons_poly(ao_lisp_cons_cons(car, ao_lisp_poly_cons(cdr)));
+}
+
+ao_poly
+ao_lisp_last(struct ao_lisp_cons *cons)
+{
+	ao_poly	l;
+	if (!ao_lisp_check_argc(_ao_lisp_atom_last, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_last, cons, 0, AO_LISP_CONS, 1))
+		return AO_LISP_NIL;
+	l = ao_lisp_arg(cons, 0);
+	while (l) {
+		struct ao_lisp_cons *list = ao_lisp_poly_cons(l);
+		if (!list->cdr)
+			return list->car;
+		l = list->cdr;
+	}
+	return AO_LISP_NIL;
+}
+
+ao_poly
+ao_lisp_length(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_length, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_length, cons, 0, AO_LISP_CONS, 1))
+		return AO_LISP_NIL;
+	return ao_lisp_int_poly(ao_lisp_cons_length(ao_lisp_poly_cons(ao_lisp_arg(cons, 0))));
+}
+
+ao_poly
+ao_lisp_quote(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_quote, cons, 1, 1))
+		return AO_LISP_NIL;
+	return ao_lisp_arg(cons, 0);
+}
+
+ao_poly
+ao_lisp_set(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_set, cons, 2, 2))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_set, cons, 0, AO_LISP_ATOM, 0))
+		return AO_LISP_NIL;
+
+	return ao_lisp_atom_set(ao_lisp_arg(cons, 0), ao_lisp_arg(cons, 1));
+}
+
+ao_poly
+ao_lisp_setq(struct ao_lisp_cons *cons)
+{
+	struct ao_lisp_cons	*expand = 0;
+	if (!ao_lisp_check_argc(_ao_lisp_atom_setq, cons, 2, 2))
+		return AO_LISP_NIL;
+	expand = ao_lisp_cons_cons(_ao_lisp_atom_set,
+				   ao_lisp_cons_cons(ao_lisp_cons_poly(ao_lisp_cons_cons(_ao_lisp_atom_quote,
+								       ao_lisp_cons_cons(cons->car, NULL))),
+						     ao_lisp_poly_cons(cons->cdr)));
+	return ao_lisp_cons_poly(expand);
+}
+
+ao_poly
+ao_lisp_cond(struct ao_lisp_cons *cons)
+{
+	ao_lisp_set_cond(cons);
+	return AO_LISP_NIL;
+}
+
+ao_poly
+ao_lisp_progn(struct ao_lisp_cons *cons)
+{
+	ao_lisp_stack->state = eval_progn;
+	ao_lisp_stack->sexprs = ao_lisp_cons_poly(cons);
+	return AO_LISP_NIL;
+}
+
+ao_poly
+ao_lisp_while(struct ao_lisp_cons *cons)
+{
+	ao_lisp_stack->state = eval_while;
+	ao_lisp_stack->sexprs = ao_lisp_cons_poly(cons);
+	return AO_LISP_NIL;
+}
+
+ao_poly
+ao_lisp_print(struct ao_lisp_cons *cons)
+{
+	ao_poly	val = AO_LISP_NIL;
+	while (cons) {
+		val = cons->car;
+		ao_lisp_poly_print(val);
+		cons = ao_lisp_poly_cons(cons->cdr);
+		if (cons)
+			printf(" ");
+	}
+	printf("\n");
+	return val;
+}
+
+ao_poly
+ao_lisp_patom(struct ao_lisp_cons *cons)
+{
+	ao_poly	val = AO_LISP_NIL;
+	while (cons) {
+		val = cons->car;
+		ao_lisp_poly_patom(val);
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+	return val;
+}
+
+ao_poly
+ao_lisp_math(struct ao_lisp_cons *cons, enum ao_lisp_builtin_id op)
+{
+	ao_poly	ret = AO_LISP_NIL;
+
+	while (cons) {
+		ao_poly		car = cons->car;
+		uint8_t		rt = ao_lisp_poly_type(ret);
+		uint8_t		ct = ao_lisp_poly_type(car);
+
+		cons = ao_lisp_poly_cons(cons->cdr);
+
+		if (rt == AO_LISP_NIL)
+			ret = car;
+
+		else if (rt == AO_LISP_INT && ct == AO_LISP_INT) {
+			int	r = ao_lisp_poly_int(ret);
+			int	c = ao_lisp_poly_int(car);
+
+			switch(op) {
+			case builtin_plus:
+				r += c;
+				break;
+			case builtin_minus:
+				r -= c;
+				break;
+			case builtin_times:
+				r *= c;
+				break;
+			case builtin_divide:
+				if (c == 0)
+					return ao_lisp_error(AO_LISP_DIVIDE_BY_ZERO, "divide by zero");
+				r /= c;
+				break;
+			case builtin_mod:
+				if (c == 0)
+					return ao_lisp_error(AO_LISP_DIVIDE_BY_ZERO, "mod by zero");
+				r %= c;
+				break;
+			default:
+				break;
+			}
+			ret = ao_lisp_int_poly(r);
+		}
+
+		else if (rt == AO_LISP_STRING && ct == AO_LISP_STRING && op == builtin_plus)
+			ret = ao_lisp_string_poly(ao_lisp_string_cat(ao_lisp_poly_string(ret),
+								     ao_lisp_poly_string(car)));
+		else
+			return ao_lisp_error(AO_LISP_INVALID, "invalid args");
+	}
+	return ret;
+}
+
+ao_poly
+ao_lisp_plus(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_math(cons, builtin_plus);
+}
+
+ao_poly
+ao_lisp_minus(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_math(cons, builtin_minus);
+}
+
+ao_poly
+ao_lisp_times(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_math(cons, builtin_times);
+}
+
+ao_poly
+ao_lisp_divide(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_math(cons, builtin_divide);
+}
+
+ao_poly
+ao_lisp_mod(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_math(cons, builtin_mod);
+}
+
+ao_poly
+ao_lisp_compare(struct ao_lisp_cons *cons, enum ao_lisp_builtin_id op)
+{
+	ao_poly	left;
+
+	if (!cons)
+		return _ao_lisp_atom_t;
+
+	left = cons->car;
+	cons = ao_lisp_poly_cons(cons->cdr);
+	while (cons) {
+		ao_poly	right = cons->car;
+
+		if (op == builtin_equal) {
+			if (left != right)
+				return AO_LISP_NIL;
+		} else {
+			uint8_t	lt = ao_lisp_poly_type(left);
+			uint8_t	rt = ao_lisp_poly_type(right);
+			if (lt == AO_LISP_INT && rt == AO_LISP_INT) {
+				int l = ao_lisp_poly_int(left);
+				int r = ao_lisp_poly_int(right);
+
+				switch (op) {
+				case builtin_less:
+					if (!(l < r))
+						return AO_LISP_NIL;
+					break;
+				case builtin_greater:
+					if (!(l > r))
+						return AO_LISP_NIL;
+					break;
+				case builtin_less_equal:
+					if (!(l <= r))
+						return AO_LISP_NIL;
+					break;
+				case builtin_greater_equal:
+					if (!(l >= r))
+						return AO_LISP_NIL;
+					break;
+				default:
+					break;
+				}
+			} else if (lt == AO_LISP_STRING && rt == AO_LISP_STRING) {
+				int c = strcmp(ao_lisp_poly_string(left),
+					       ao_lisp_poly_string(right));
+				switch (op) {
+				case builtin_less:
+					if (!(c < 0))
+						return AO_LISP_NIL;
+					break;
+				case builtin_greater:
+					if (!(c > 0))
+						return AO_LISP_NIL;
+					break;
+				case builtin_less_equal:
+					if (!(c <= 0))
+						return AO_LISP_NIL;
+					break;
+				case builtin_greater_equal:
+					if (!(c >= 0))
+						return AO_LISP_NIL;
+					break;
+				default:
+					break;
+				}
+			}
+		}
+		left = right;
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+	return _ao_lisp_atom_t;
+}
+
+ao_poly
+ao_lisp_equal(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_compare(cons, builtin_equal);
+}
+
+ao_poly
+ao_lisp_less(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_compare(cons, builtin_less);
+}
+
+ao_poly
+ao_lisp_greater(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_compare(cons, builtin_greater);
+}
+
+ao_poly
+ao_lisp_less_equal(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_compare(cons, builtin_less_equal);
+}
+
+ao_poly
+ao_lisp_greater_equal(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_compare(cons, builtin_greater_equal);
+}
+
+ao_poly
+ao_lisp_pack(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_pack, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_pack, cons, 0, AO_LISP_CONS, 1))
+		return AO_LISP_NIL;
+	return ao_lisp_string_pack(ao_lisp_poly_cons(ao_lisp_arg(cons, 0)));
+}
+
+ao_poly
+ao_lisp_unpack(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_unpack, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_unpack, cons, 0, AO_LISP_STRING, 0))
+		return AO_LISP_NIL;
+	return ao_lisp_string_unpack(ao_lisp_poly_string(ao_lisp_arg(cons, 0)));
+}
+
+ao_poly
+ao_lisp_flush(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_flush, cons, 0, 0))
+		return AO_LISP_NIL;
+	ao_lisp_os_flush();
+	return _ao_lisp_atom_t;
+}
+
+ao_poly
+ao_lisp_led(struct ao_lisp_cons *cons)
+{
+	ao_poly led;
+	if (!ao_lisp_check_argc(_ao_lisp_atom_led, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_led, cons, 0, AO_LISP_INT, 0))
+		return AO_LISP_NIL;
+	led = ao_lisp_arg(cons, 0);
+	ao_lisp_os_led(ao_lisp_poly_int(led));
+	return led;
+}
+
+ao_poly
+ao_lisp_delay(struct ao_lisp_cons *cons)
+{
+	ao_poly delay;
+	if (!ao_lisp_check_argc(_ao_lisp_atom_led, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_led, cons, 0, AO_LISP_INT, 0))
+		return AO_LISP_NIL;
+	delay = ao_lisp_arg(cons, 0);
+	ao_lisp_os_delay(ao_lisp_poly_int(delay));
+	return delay;
+}
+
+ao_poly
+ao_lisp_do_eval(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_eval, cons, 1, 1))
+		return AO_LISP_NIL;
+	ao_lisp_stack->state = eval_sexpr;
+	return cons->car;
+}
+
+ao_poly
+ao_lisp_do_read(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_read, cons, 0, 0))
+		return AO_LISP_NIL;
+	return ao_lisp_read();
+}
+
+ao_poly
+ao_lisp_do_collect(struct ao_lisp_cons *cons)
+{
+	int	free;
+	(void) cons;
+	free = ao_lisp_collect(AO_LISP_COLLECT_FULL);
+	return ao_lisp_int_poly(free);
+}
+
+const ao_lisp_func_t ao_lisp_builtins[] = {
+	[builtin_eval] = ao_lisp_do_eval,
+	[builtin_read] = ao_lisp_do_read,
+	[builtin_lambda] = ao_lisp_lambda,
+	[builtin_lexpr] = ao_lisp_lexpr,
+	[builtin_nlambda] = ao_lisp_nlambda,
+	[builtin_macro] = ao_lisp_macro,
+	[builtin_car] = ao_lisp_car,
+	[builtin_cdr] = ao_lisp_cdr,
+	[builtin_cons] = ao_lisp_cons,
+	[builtin_last] = ao_lisp_last,
+	[builtin_length] = ao_lisp_length,
+	[builtin_quote] = ao_lisp_quote,
+	[builtin_set] = ao_lisp_set,
+	[builtin_setq] = ao_lisp_setq,
+	[builtin_cond] = ao_lisp_cond,
+	[builtin_progn] = ao_lisp_progn,
+	[builtin_while] = ao_lisp_while,
+	[builtin_print] = ao_lisp_print,
+	[builtin_patom] = ao_lisp_patom,
+	[builtin_plus] = ao_lisp_plus,
+	[builtin_minus] = ao_lisp_minus,
+	[builtin_times] = ao_lisp_times,
+	[builtin_divide] = ao_lisp_divide,
+	[builtin_mod] = ao_lisp_mod,
+	[builtin_equal] = ao_lisp_equal,
+	[builtin_less] = ao_lisp_less,
+	[builtin_greater] = ao_lisp_greater,
+	[builtin_less_equal] = ao_lisp_less_equal,
+	[builtin_greater_equal] = ao_lisp_greater_equal,
+	[builtin_pack] = ao_lisp_pack,
+	[builtin_unpack] = ao_lisp_unpack,
+	[builtin_flush] = ao_lisp_flush,
+	[builtin_led] = ao_lisp_led,
+	[builtin_delay] = ao_lisp_delay,
+	[builtin_save] = ao_lisp_save,
+	[builtin_restore] = ao_lisp_restore,
+	[builtin_call_cc] = ao_lisp_call_cc,
+	[builtin_collect] = ao_lisp_do_collect,
+};
+
diff --git a/src/lisp/ao_lisp_cons.c b/src/lisp/ao_lisp_cons.c
new file mode 100644
index 00000000..d2b60c9a
--- /dev/null
+++ b/src/lisp/ao_lisp_cons.c
@@ -0,0 +1,143 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
+static void cons_mark(void *addr)
+{
+	struct ao_lisp_cons	*cons = addr;
+
+	for (;;) {
+		ao_lisp_poly_mark(cons->car, 1);
+		cons = ao_lisp_poly_cons(cons->cdr);
+		if (!cons)
+			break;
+		if (ao_lisp_mark_memory(&ao_lisp_cons_type, cons))
+			break;
+	}
+}
+
+static int cons_size(void *addr)
+{
+	(void) addr;
+	return sizeof (struct ao_lisp_cons);
+}
+
+static void cons_move(void *addr)
+{
+	struct ao_lisp_cons	*cons = addr;
+
+	if (!cons)
+		return;
+
+	for (;;) {
+		struct ao_lisp_cons	*cdr;
+		int			ret;
+
+		MDBG_MOVE("cons_move start %d (%d, %d)\n",
+			  MDBG_OFFSET(cons), MDBG_OFFSET(ao_lisp_ref(cons->car)), MDBG_OFFSET(ao_lisp_ref(cons->cdr)));
+		(void) ao_lisp_poly_move(&cons->car, 1);
+		cdr = ao_lisp_poly_cons(cons->cdr);
+		if (!cdr)
+			break;
+		ret = ao_lisp_move_memory(&ao_lisp_cons_type, (void **) &cdr);
+		if (cdr != ao_lisp_poly_cons(cons->cdr))
+			cons->cdr = ao_lisp_cons_poly(cdr);
+		MDBG_MOVE("cons_move end %d (%d, %d)\n",
+			  MDBG_OFFSET(cons), MDBG_OFFSET(ao_lisp_ref(cons->car)), MDBG_OFFSET(ao_lisp_ref(cons->cdr)));
+		if (ret)
+			break;
+		cons = cdr;
+	}
+}
+
+const struct ao_lisp_type ao_lisp_cons_type = {
+	.mark = cons_mark,
+	.size = cons_size,
+	.move = cons_move,
+	.name = "cons",
+};
+
+struct ao_lisp_cons *ao_lisp_cons_free_list;
+
+struct ao_lisp_cons *
+ao_lisp_cons_cons(ao_poly car, struct ao_lisp_cons *cdr)
+{
+	struct ao_lisp_cons	*cons;
+
+	if (ao_lisp_cons_free_list) {
+		cons = ao_lisp_cons_free_list;
+		ao_lisp_cons_free_list = ao_lisp_poly_cons(cons->cdr);
+	} else {
+		ao_lisp_poly_stash(0, car);
+		ao_lisp_cons_stash(0, cdr);
+		cons = ao_lisp_alloc(sizeof (struct ao_lisp_cons));
+		car = ao_lisp_poly_fetch(0);
+		cdr = ao_lisp_cons_fetch(0);
+		if (!cons)
+			return NULL;
+	}
+	cons->car = car;
+	cons->cdr = ao_lisp_cons_poly(cdr);
+	return cons;
+}
+
+void
+ao_lisp_cons_free(struct ao_lisp_cons *cons)
+{
+	while (cons) {
+		ao_poly cdr = cons->cdr;
+		cons->cdr = ao_lisp_cons_poly(ao_lisp_cons_free_list);
+		ao_lisp_cons_free_list = cons;
+		cons = ao_lisp_poly_cons(cdr);
+	}
+}
+
+void
+ao_lisp_cons_print(ao_poly c)
+{
+	struct ao_lisp_cons *cons = ao_lisp_poly_cons(c);
+	int	first = 1;
+	printf("(");
+	while (cons) {
+		if (!first)
+			printf(" ");
+		ao_lisp_poly_print(cons->car);
+		cons = ao_lisp_poly_cons(cons->cdr);
+		first = 0;
+	}
+	printf(")");
+}
+
+void
+ao_lisp_cons_patom(ao_poly c)
+{
+	struct ao_lisp_cons *cons = ao_lisp_poly_cons(c);
+
+	while (cons) {
+		ao_lisp_poly_patom(cons->car);
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+}
+
+int
+ao_lisp_cons_length(struct ao_lisp_cons *cons)
+{
+	int	len = 0;
+	while (cons) {
+		len++;
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+	return len;
+}
diff --git a/src/lisp/ao_lisp_const.lisp b/src/lisp/ao_lisp_const.lisp
new file mode 100644
index 00000000..3c8fd21b
--- /dev/null
+++ b/src/lisp/ao_lisp_const.lisp
@@ -0,0 +1,184 @@
+;
+; Copyright © 2016 Keith Packard <keithp@keithp.com>
+;
+; This program is free software; you can redistribute it and/or modify
+; it under the terms of the GNU General Public License as published by
+; the Free Software Foundation, either version 2 of the License, or
+; (at your option) any later version.
+;
+; This program is distributed in the hope that it will be useful, but
+; WITHOUT ANY WARRANTY; without even the implied warranty of
+; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+; General Public License for more details.
+;
+; Lisp code placed in ROM
+
+					; return a list containing all of the arguments
+
+(set (quote list) (lexpr (l) l))
+
+					;
+					; Define a variable without returning the value
+					; Useful when defining functions to avoid
+					; having lots of output generated
+					;
+
+(setq def (macro (name val rest)
+		 (list
+		  'progn
+		  (list
+		   'set
+		   (list 'quote name)
+		   val)
+		  (list 'quote name)
+		  )
+		 )
+      )
+
+					;
+					; A slightly more convenient form
+					; for defining lambdas.
+					;
+					; (defun <name> (<params>) s-exprs)
+					;
+
+(def defun (macro (name args exprs)
+		  (list
+		   def
+		   name
+		   (cons 'lambda (cons args exprs))
+		   )
+		  )
+     )
+
+					; basic list accessors
+
+
+(defun cadr (l) (car (cdr l)))
+
+(defun caddr (l) (car (cdr (cdr l))))
+
+(defun nth (list n)
+  (cond ((= n 0) (car list))
+	((nth (cdr list) (1- n)))
+	)
+  )
+
+					; simple math operators
+
+(defun 1+ (x) (+ x 1))
+(defun 1- (x) (- x 1))
+
+					; define a set of local
+					; variables and then evaluate
+					; a list of sexprs
+					;
+					; (let (var-defines) sexprs)
+					;
+					; where var-defines are either
+					;
+					; (name value)
+					;
+					; or
+					;
+					; (name)
+					;
+					; e.g.
+					;
+					; (let ((x 1) (y)) (setq y (+ x 1)) y)
+
+(def let (macro (vars exprs)
+		((lambda (make-names make-exprs make-nils)
+
+					;
+					; make the list of names in the let
+					;
+
+		   (setq make-names (lambda (vars)
+				      (cond (vars
+					     (cons (car (car vars))
+						   (make-names (cdr vars))))
+					    )
+				      )
+			 )
+
+					; the set of expressions is
+					; the list of set expressions
+					; pre-pended to the
+					; expressions to evaluate
+
+		   (setq make-exprs (lambda (vars exprs)
+				      (cond (vars (cons
+						   (list set
+							 (list quote
+							       (car (car vars))
+							       )
+							 (cadr (car vars))
+							 )
+						   (make-exprs (cdr vars) exprs)
+						   )
+						  )
+					    (exprs)
+					    )
+				      )
+			 )
+
+					; the parameters to the lambda is a list
+					; of nils of the right length
+
+		   (setq make-nils (lambda (vars)
+				     (cond (vars (cons nil (make-nils (cdr vars))))
+					   )
+				     )
+			 )
+					; prepend the set operations
+					; to the expressions
+
+		   (setq exprs (make-exprs vars exprs))
+
+					; build the lambda.
+
+		   (cons (cons 'lambda (cons (make-names vars) exprs))
+			 (make-nils vars)
+			 )
+		   )
+		 ()
+		 ()
+		 ()
+		 )
+		)
+     )
+
+					; boolean operators
+
+(def or (lexpr (l)
+	       (let ((ret nil))
+		 (while l
+		   (cond ((setq ret (car l))
+			  (setq l nil))
+			 ((setq l (cdr l)))))
+		 ret
+		 )
+	       )
+     )
+
+					; execute to resolve macros
+
+(or nil t)
+
+(def and (lexpr (l)
+	       (let ((ret t))
+		 (while l
+		   (cond ((setq ret (car l))
+			  (setq l (cdr l)))
+			 ((setq ret (setq l nil)))
+			 )
+		   )
+		 ret
+		 )
+	       )
+     )
+
+					; execute to resolve macros
+
+(and t nil)
diff --git a/src/lisp/ao_lisp_error.c b/src/lisp/ao_lisp_error.c
new file mode 100644
index 00000000..54a9be10
--- /dev/null
+++ b/src/lisp/ao_lisp_error.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+#include <stdarg.h>
+
+void
+ao_lisp_error_poly(char *name, ao_poly poly, ao_poly last)
+{
+	int first = 1;
+	printf("\t\t%s(", name);
+	if (ao_lisp_poly_type(poly) == AO_LISP_CONS) {
+		if (poly) {
+			while (poly) {
+				struct ao_lisp_cons *cons = ao_lisp_poly_cons(poly);
+				if (!first)
+					printf("\t\t         ");
+				else
+					first = 0;
+				ao_lisp_poly_print(cons->car);
+				printf("\n");
+				if (poly == last)
+					break;
+				poly = cons->cdr;
+			}
+			printf("\t\t         )\n");
+		} else
+			printf(")\n");
+	} else {
+		ao_lisp_poly_print(poly);
+		printf("\n");
+	}
+}
+
+static void tabs(int indent)
+{
+	while (indent--)
+		printf("\t");
+}
+
+void
+ao_lisp_error_frame(int indent, char *name, struct ao_lisp_frame *frame)
+{
+	int			f;
+
+	tabs(indent);
+	printf ("%s{", name);
+	if (frame) {
+		if (frame->type & AO_LISP_FRAME_PRINT)
+			printf("recurse...");
+		else {
+			frame->type |= AO_LISP_FRAME_PRINT;
+			for (f = 0; f < frame->num; f++) {
+				if (f != 0) {
+					tabs(indent);
+					printf("         ");
+				}
+				ao_lisp_poly_print(frame->vals[f].atom);
+				printf(" = ");
+				ao_lisp_poly_print(frame->vals[f].val);
+				printf("\n");
+			}
+			if (frame->prev)
+				ao_lisp_error_frame(indent + 1, "prev:   ", ao_lisp_poly_frame(frame->prev));
+			frame->type &= ~AO_LISP_FRAME_PRINT;
+		}
+		tabs(indent);
+		printf("        }\n");
+	} else
+		printf ("}\n");
+}
+
+
+ao_poly
+ao_lisp_error(int error, char *format, ...)
+{
+	va_list	args;
+
+	ao_lisp_exception |= error;
+	va_start(args, format);
+	vprintf(format, args);
+	va_end(args);
+	printf("\n");
+	printf("Value: "); ao_lisp_poly_print(ao_lisp_v); printf("\n");
+	printf("Stack:\n");
+	ao_lisp_stack_print(ao_lisp_stack_poly(ao_lisp_stack));
+	printf("Globals:\n\t");
+	ao_lisp_frame_print(ao_lisp_frame_poly(ao_lisp_frame_global));
+	printf("\n");
+	return AO_LISP_NIL;
+}
diff --git a/src/lisp/ao_lisp_eval.c b/src/lisp/ao_lisp_eval.c
new file mode 100644
index 00000000..3be7c9c4
--- /dev/null
+++ b/src/lisp/ao_lisp_eval.c
@@ -0,0 +1,531 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+#include <assert.h>
+
+struct ao_lisp_stack		*ao_lisp_stack;
+ao_poly				ao_lisp_v;
+
+ao_poly
+ao_lisp_set_cond(struct ao_lisp_cons *c)
+{
+	ao_lisp_stack->state = eval_cond;
+	ao_lisp_stack->sexprs = ao_lisp_cons_poly(c);
+	return AO_LISP_NIL;
+}
+
+static int
+func_type(ao_poly func)
+{
+	if (func == AO_LISP_NIL)
+		return ao_lisp_error(AO_LISP_INVALID, "func is nil");
+	switch (ao_lisp_poly_type(func)) {
+	case AO_LISP_BUILTIN:
+		return ao_lisp_poly_builtin(func)->args & AO_LISP_FUNC_MASK;
+	case AO_LISP_LAMBDA:
+		return ao_lisp_poly_lambda(func)->args;
+	case AO_LISP_STACK:
+		return AO_LISP_FUNC_LAMBDA;
+	default:
+		ao_lisp_error(AO_LISP_INVALID, "not a func");
+		return -1;
+	}
+}
+
+/*
+ * Flattened eval to avoid stack issues
+ */
+
+/*
+ * Evaluate an s-expression
+ *
+ * For a list, evaluate all of the elements and
+ * then execute the resulting function call.
+ *
+ * Each element of the list is evaluated in
+ * a clean stack context.
+ *
+ * The current stack state is set to 'formal' so that
+ * when the evaluation is complete, the value
+ * will get appended to the values list.
+ *
+ * For other types, compute the value directly.
+ */
+
+static int
+ao_lisp_eval_sexpr(void)
+{
+	DBGI("sexpr: "); DBG_POLY(ao_lisp_v); DBG("\n");
+	switch (ao_lisp_poly_type(ao_lisp_v)) {
+	case AO_LISP_CONS:
+		if (ao_lisp_v == AO_LISP_NIL) {
+			if (!ao_lisp_stack->values) {
+				/*
+				 * empty list evaluates to empty list
+				 */
+				ao_lisp_v = AO_LISP_NIL;
+				ao_lisp_stack->state = eval_val;
+			} else {
+				/*
+				 * done with arguments, go execute it
+				 */
+				ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->values)->car;
+				ao_lisp_stack->state = eval_exec;
+			}
+		} else {
+			if (!ao_lisp_stack->values)
+				ao_lisp_stack->list = ao_lisp_v;
+			/*
+			 * Evaluate another argument and then switch
+			 * to 'formal' to add the value to the values
+			 * list
+			 */
+			ao_lisp_stack->sexprs = ao_lisp_v;
+			ao_lisp_stack->state = eval_formal;
+			if (!ao_lisp_stack_push())
+				return 0;
+			/*
+			 * push will reset the state to 'sexpr', which
+			 * will evaluate the expression
+			 */
+			ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
+		}
+		break;
+	case AO_LISP_ATOM:
+		DBGI("..frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+		ao_lisp_v = ao_lisp_atom_get(ao_lisp_v);
+		/* fall through */
+	case AO_LISP_INT:
+	case AO_LISP_STRING:
+	case AO_LISP_BUILTIN:
+	case AO_LISP_LAMBDA:
+		ao_lisp_stack->state = eval_val;
+		break;
+	}
+	DBGI(".. result "); DBG_POLY(ao_lisp_v); DBG("\n");
+	return 1;
+}
+
+/*
+ * A value has been computed.
+ *
+ * If the value was computed from a macro,
+ * then we want to reset the current context
+ * to evaluate the macro result again.
+ *
+ * If not a macro, then pop the stack.
+ * If the stack is empty, we're done.
+ * Otherwise, the stack will contain
+ * the next state.
+ */
+
+static int
+ao_lisp_eval_val(void)
+{
+	DBGI("val: "); DBG_POLY(ao_lisp_v); DBG("\n");
+	/*
+	 * Value computed, pop the stack
+	 * to figure out what to do with the value
+	 */
+	ao_lisp_stack_pop();
+	DBGI("..state %d\n", ao_lisp_stack ? ao_lisp_stack->state : -1);
+	return 1;
+}
+
+/*
+ * A formal has been computed.
+ *
+ * If this is the first formal, then check to see if we've got a
+ * lamda/lexpr or macro/nlambda.
+ *
+ * For lambda/lexpr, go compute another formal.  This will terminate
+ * when the sexpr state sees nil.
+ *
+ * For macro/nlambda, we're done, so move the sexprs into the values
+ * and go execute it.
+ *
+ * Macros have an additional step of saving a stack frame holding the
+ * macro value execution context, which then gets the result of the
+ * macro to run
+ */
+
+static int
+ao_lisp_eval_formal(void)
+{
+	ao_poly			formal;
+	struct ao_lisp_stack	*prev;
+
+	DBGI("formal: "); DBG_POLY(ao_lisp_v); DBG("\n");
+
+	/* Check what kind of function we've got */
+	if (!ao_lisp_stack->values) {
+		switch (func_type(ao_lisp_v)) {
+		case AO_LISP_FUNC_LAMBDA:
+		case AO_LISP_FUNC_LEXPR:
+			DBGI(".. lambda or lexpr\n");
+			break;
+		case AO_LISP_FUNC_MACRO:
+			/* Evaluate the result once more */
+			ao_lisp_stack->state = eval_macro;
+			if (!ao_lisp_stack_push())
+				return 0;
+
+			/* After the function returns, take that
+			 * value and re-evaluate it
+			 */
+			prev = ao_lisp_poly_stack(ao_lisp_stack->prev);
+			ao_lisp_stack->sexprs = prev->sexprs;
+
+			DBGI(".. start macro\n");
+			DBGI(".. sexprs       "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+			DBGI(".. values       "); DBG_POLY(ao_lisp_stack->values); DBG("\n");
+			DBG_FRAMES();
+
+			/* fall through ... */
+		case AO_LISP_FUNC_NLAMBDA:
+			DBGI(".. nlambda or macro\n");
+
+			/* use the raw sexprs as values */
+			ao_lisp_stack->values = ao_lisp_stack->sexprs;
+			ao_lisp_stack->values_tail = AO_LISP_NIL;
+			ao_lisp_stack->state = eval_exec;
+
+			/* ready to execute now */
+			return 1;
+		case -1:
+			return 0;
+		}
+	}
+
+	/* Append formal to list of values */
+	formal = ao_lisp_cons_poly(ao_lisp_cons_cons(ao_lisp_v, NULL));
+	if (!formal)
+		return 0;
+
+	if (ao_lisp_stack->values_tail)
+		ao_lisp_poly_cons(ao_lisp_stack->values_tail)->cdr = formal;
+	else
+		ao_lisp_stack->values = formal;
+	ao_lisp_stack->values_tail = formal;
+
+	DBGI(".. values "); DBG_POLY(ao_lisp_stack->values); DBG("\n");
+
+	/*
+	 * Step to the next argument, if this is last, then
+	 * 'sexpr' will end up switching to 'exec'
+	 */
+	ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
+
+	ao_lisp_stack->state = eval_sexpr;
+
+	DBGI(".. "); DBG_POLY(ao_lisp_v); DBG("\n");
+	return 1;
+}
+
+/*
+ * Start executing a function call
+ *
+ * Most builtins are easy, just call the function.
+ * 'cond' is magic; it sticks the list of clauses
+ * in 'sexprs' and switches to 'cond' state. That
+ * bit of magic is done in ao_lisp_set_cond.
+ *
+ * Lambdas build a new frame to hold the locals and
+ * then re-use the current stack context to evaluate
+ * the s-expression from the lambda.
+ */
+
+static int
+ao_lisp_eval_exec(void)
+{
+	ao_poly v;
+	struct ao_lisp_builtin	*builtin;
+
+	DBGI("exec: "); DBG_POLY(ao_lisp_v); DBG(" values "); DBG_POLY(ao_lisp_stack->values); DBG ("\n");
+	ao_lisp_stack->sexprs = AO_LISP_NIL;
+	switch (ao_lisp_poly_type(ao_lisp_v)) {
+	case AO_LISP_BUILTIN:
+		ao_lisp_stack->state = eval_val;
+		builtin = ao_lisp_poly_builtin(ao_lisp_v);
+		v = ao_lisp_func(builtin) (
+			ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->values)->cdr));
+		DBG_DO(if (!ao_lisp_exception && ao_lisp_poly_builtin(ao_lisp_v)->func == builtin_set) {
+				struct ao_lisp_cons *cons = ao_lisp_poly_cons(ao_lisp_stack->values);
+				ao_poly atom = ao_lisp_arg(cons, 1);
+				ao_poly val = ao_lisp_arg(cons, 2);
+				DBGI("set "); DBG_POLY(atom); DBG(" = "); DBG_POLY(val); DBG("\n");
+			});
+		builtin = ao_lisp_poly_builtin(ao_lisp_v);
+		if (builtin->args & AO_LISP_FUNC_FREE_ARGS && !ao_lisp_stack_marked(ao_lisp_stack))
+			ao_lisp_cons_free(ao_lisp_poly_cons(ao_lisp_stack->values));
+
+		ao_lisp_v = v;
+		ao_lisp_stack->values = AO_LISP_NIL;
+		ao_lisp_stack->values_tail = AO_LISP_NIL;
+		DBGI(".. result "); DBG_POLY(ao_lisp_v); DBG ("\n");
+		DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+		break;
+	case AO_LISP_LAMBDA:
+		DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+		ao_lisp_stack->state = eval_progn;
+		v = ao_lisp_lambda_eval();
+		ao_lisp_stack->sexprs = v;
+		ao_lisp_stack->values = AO_LISP_NIL;
+		ao_lisp_stack->values_tail = AO_LISP_NIL;
+		DBGI(".. sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+		DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+		break;
+	case AO_LISP_STACK:
+		DBGI(".. stack "); DBG_POLY(ao_lisp_v); DBG("\n");
+		ao_lisp_v = ao_lisp_stack_eval();
+		DBGI(".. value "); DBG_POLY(ao_lisp_v); DBG("\n");
+		DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+		break;
+	}
+	return 1;
+}
+
+/*
+ * Start evaluating the next cond clause
+ *
+ * If the list of clauses is empty, then
+ * the result of the cond is nil.
+ *
+ * Otherwise, set the current stack state to 'cond_test' and create a
+ * new stack context to evaluate the test s-expression. Once that's
+ * complete, we'll land in 'cond_test' to finish the clause.
+ */
+static int
+ao_lisp_eval_cond(void)
+{
+	DBGI("cond: "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+	DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+	DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+	if (!ao_lisp_stack->sexprs) {
+		ao_lisp_v = AO_LISP_NIL;
+		ao_lisp_stack->state = eval_val;
+	} else {
+		ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car;
+		if (!ao_lisp_v || ao_lisp_poly_type(ao_lisp_v) != AO_LISP_CONS) {
+			ao_lisp_error(AO_LISP_INVALID, "invalid cond clause");
+			return 0;
+		}
+		ao_lisp_v = ao_lisp_poly_cons(ao_lisp_v)->car;
+		ao_lisp_stack->state = eval_cond_test;
+		if (!ao_lisp_stack_push())
+			return 0;
+	}
+	return 1;
+}
+
+/*
+ * Finish a cond clause.
+ *
+ * Check the value from the test expression, if
+ * non-nil, then set up to evaluate the value expression.
+ *
+ * Otherwise, step to the next clause and go back to the 'cond'
+ * state
+ */
+static int
+ao_lisp_eval_cond_test(void)
+{
+	DBGI("cond_test: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+	DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+	DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+	if (ao_lisp_v) {
+		struct ao_lisp_cons *car = ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car);
+		ao_poly c = car->cdr;
+
+		if (c) {
+			ao_lisp_stack->state = eval_progn;
+			ao_lisp_stack->sexprs = c;
+		} else
+			ao_lisp_stack->state = eval_val;
+	} else {
+		ao_lisp_stack->sexprs = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
+		DBGI("next cond: "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+		ao_lisp_stack->state = eval_cond;
+	}
+	return 1;
+}
+
+/*
+ * Evaluate a list of sexprs, returning the value from the last one.
+ *
+ * ao_lisp_progn records the list in stack->sexprs, so we just need to
+ * walk that list. Set ao_lisp_v to the car of the list and jump to
+ * eval_sexpr. When that's done, it will land in eval_val. For all but
+ * the last, leave a stack frame with eval_progn set so that we come
+ * back here. For the last, don't add a stack frame so that we can
+ * just continue on.
+ */
+static int
+ao_lisp_eval_progn(void)
+{
+	DBGI("progn: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+	DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+	DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+
+	if (!ao_lisp_stack->sexprs) {
+		ao_lisp_v = AO_LISP_NIL;
+		ao_lisp_stack->state = eval_val;
+	} else {
+		ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car;
+		ao_lisp_stack->sexprs = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
+
+		/* If there are more sexprs to do, then come back here, otherwise
+		 * return the value of the last one by just landing in eval_sexpr
+		 */
+		if (ao_lisp_stack->sexprs) {
+			ao_lisp_stack->state = eval_progn;
+			if (!ao_lisp_stack_push())
+				return 0;
+		}
+		ao_lisp_stack->state = eval_sexpr;
+	}
+	return 1;
+}
+
+/*
+ * Conditionally execute a list of sexprs while the first is true
+ */
+static int
+ao_lisp_eval_while(void)
+{
+	DBGI("while: "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+	DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+	DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+
+	ao_lisp_stack->values = ao_lisp_v;
+	if (!ao_lisp_stack->sexprs) {
+		ao_lisp_v = AO_LISP_NIL;
+		ao_lisp_stack->state = eval_val;
+	} else {
+		ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->car;
+		ao_lisp_stack->state = eval_while_test;
+		if (!ao_lisp_stack_push())
+			return 0;
+	}
+	return 1;
+}
+
+/*
+ * Check the while condition, terminate the loop if nil. Otherwise keep going
+ */
+static int
+ao_lisp_eval_while_test(void)
+{
+	DBGI("while_test: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+	DBGI(".. frame "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");
+	DBGI(".. saved frame "); DBG_POLY(ao_lisp_stack->frame); DBG("\n");
+
+	if (ao_lisp_v) {
+		ao_lisp_stack->values = ao_lisp_v;
+		ao_lisp_v = ao_lisp_poly_cons(ao_lisp_stack->sexprs)->cdr;
+		ao_lisp_stack->state = eval_while;
+		if (!ao_lisp_stack_push())
+			return 0;
+		ao_lisp_stack->state = eval_progn;
+		ao_lisp_stack->sexprs = ao_lisp_v;
+	}
+	else
+	{
+		ao_lisp_stack->state = eval_val;
+		ao_lisp_v = ao_lisp_stack->values;
+	}
+	return 1;
+}
+
+/*
+ * Replace the original sexpr with the macro expansion, then
+ * execute that
+ */
+static int
+ao_lisp_eval_macro(void)
+{
+	DBGI("macro: "); DBG_POLY(ao_lisp_v); DBG(" sexprs "); DBG_POLY(ao_lisp_stack->sexprs); DBG("\n");
+
+	if (ao_lisp_v == AO_LISP_NIL)
+		ao_lisp_abort();
+	if (ao_lisp_poly_type(ao_lisp_v) == AO_LISP_CONS) {
+		*ao_lisp_poly_cons(ao_lisp_stack->sexprs) = *ao_lisp_poly_cons(ao_lisp_v);
+		ao_lisp_v = ao_lisp_stack->sexprs;
+		DBGI("sexprs rewritten to: "); DBG_POLY(ao_lisp_v); DBG("\n");
+	}
+	ao_lisp_stack->sexprs = AO_LISP_NIL;
+	ao_lisp_stack->state = eval_sexpr;
+	return 1;
+}
+
+static int (*const evals[])(void) = {
+	[eval_sexpr] = ao_lisp_eval_sexpr,
+	[eval_val] = ao_lisp_eval_val,
+	[eval_formal] = ao_lisp_eval_formal,
+	[eval_exec] = ao_lisp_eval_exec,
+	[eval_cond] = ao_lisp_eval_cond,
+	[eval_cond_test] = ao_lisp_eval_cond_test,
+	[eval_progn] = ao_lisp_eval_progn,
+	[eval_while] = ao_lisp_eval_while,
+	[eval_while_test] = ao_lisp_eval_while_test,
+	[eval_macro] = ao_lisp_eval_macro,
+};
+
+const char *ao_lisp_state_names[] = {
+	"sexpr",
+	"val",
+	"formal",
+	"exec",
+	"cond",
+	"cond_test",
+	"progn",
+};
+
+/*
+ * Called at restore time to reset all execution state
+ */
+
+void
+ao_lisp_eval_clear_globals(void)
+{
+	ao_lisp_stack = NULL;
+	ao_lisp_frame_current = NULL;
+	ao_lisp_v = AO_LISP_NIL;
+}
+
+int
+ao_lisp_eval_restart(void)
+{
+	return ao_lisp_stack_push();
+}
+
+ao_poly
+ao_lisp_eval(ao_poly _v)
+{
+	ao_lisp_v = _v;
+
+	if (!ao_lisp_stack_push())
+		return AO_LISP_NIL;
+
+	while (ao_lisp_stack) {
+		if (!(*evals[ao_lisp_stack->state])() || ao_lisp_exception) {
+			ao_lisp_stack_clear();
+			return AO_LISP_NIL;
+		}
+	}
+	DBG_DO(if (ao_lisp_frame_current) {DBGI("frame left as "); DBG_POLY(ao_lisp_frame_poly(ao_lisp_frame_current)); DBG("\n");});
+	ao_lisp_frame_current = NULL;
+	return ao_lisp_v;
+}
diff --git a/src/lisp/ao_lisp_frame.c b/src/lisp/ao_lisp_frame.c
new file mode 100644
index 00000000..05f6d253
--- /dev/null
+++ b/src/lisp/ao_lisp_frame.c
@@ -0,0 +1,293 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
+static inline int
+frame_num_size(int num)
+{
+	return sizeof (struct ao_lisp_frame) + num * sizeof (struct ao_lisp_val);
+}
+
+static int
+frame_size(void *addr)
+{
+	struct ao_lisp_frame	*frame = addr;
+	return frame_num_size(frame->num);
+}
+
+static void
+frame_mark(void *addr)
+{
+	struct ao_lisp_frame	*frame = addr;
+	int			f;
+
+	for (;;) {
+		MDBG_MOVE("frame mark %d\n", MDBG_OFFSET(frame));
+		if (!AO_LISP_IS_POOL(frame))
+			break;
+		for (f = 0; f < frame->num; f++) {
+			struct ao_lisp_val	*v = &frame->vals[f];
+
+			ao_lisp_poly_mark(v->val, 0);
+			MDBG_MOVE("frame mark atom %s %d val %d at %d\n",
+				  ao_lisp_poly_atom(v->atom)->name,
+				  MDBG_OFFSET(ao_lisp_ref(v->atom)),
+				  MDBG_OFFSET(ao_lisp_ref(v->val)), f);
+		}
+		frame = ao_lisp_poly_frame(frame->prev);
+		MDBG_MOVE("frame next %d\n", MDBG_OFFSET(frame));
+		if (!frame)
+			break;
+		if (ao_lisp_mark_memory(&ao_lisp_frame_type, frame))
+			break;
+	}
+}
+
+static void
+frame_move(void *addr)
+{
+	struct ao_lisp_frame	*frame = addr;
+	int			f;
+
+	for (;;) {
+		struct ao_lisp_frame	*prev;
+		int			ret;
+
+		MDBG_MOVE("frame move %d\n", MDBG_OFFSET(frame));
+		if (!AO_LISP_IS_POOL(frame))
+			break;
+		for (f = 0; f < frame->num; f++) {
+			struct ao_lisp_val	*v = &frame->vals[f];
+
+			ao_lisp_poly_move(&v->atom, 0);
+			ao_lisp_poly_move(&v->val, 0);
+			MDBG_MOVE("frame move atom %s %d val %d at %d\n",
+				  ao_lisp_poly_atom(v->atom)->name,
+				  MDBG_OFFSET(ao_lisp_ref(v->atom)),
+				  MDBG_OFFSET(ao_lisp_ref(v->val)), f);
+		}
+		prev = ao_lisp_poly_frame(frame->prev);
+		if (!prev)
+			break;
+		ret = ao_lisp_move_memory(&ao_lisp_frame_type, (void **) &prev);
+		if (prev != ao_lisp_poly_frame(frame->prev)) {
+			MDBG_MOVE("frame prev moved from %d to %d\n",
+				  MDBG_OFFSET(ao_lisp_poly_frame(frame->prev)),
+				  MDBG_OFFSET(prev));
+			frame->prev = ao_lisp_frame_poly(prev);
+		}
+		if (ret)
+			break;
+		frame = prev;
+	}
+}
+
+const struct ao_lisp_type ao_lisp_frame_type = {
+	.mark = frame_mark,
+	.size = frame_size,
+	.move = frame_move,
+	.name = "frame",
+};
+
+void
+ao_lisp_frame_print(ao_poly p)
+{
+	struct ao_lisp_frame	*frame = ao_lisp_poly_frame(p);
+	int			f;
+
+	printf ("{");
+	if (frame) {
+		if (frame->type & AO_LISP_FRAME_PRINT)
+			printf("recurse...");
+		else {
+			frame->type |= AO_LISP_FRAME_PRINT;
+			for (f = 0; f < frame->num; f++) {
+				if (f != 0)
+					printf(", ");
+				ao_lisp_poly_print(frame->vals[f].atom);
+				printf(" = ");
+				ao_lisp_poly_print(frame->vals[f].val);
+			}
+			if (frame->prev)
+				ao_lisp_poly_print(frame->prev);
+			frame->type &= ~AO_LISP_FRAME_PRINT;
+		}
+	}
+	printf("}");
+}
+
+static int
+ao_lisp_frame_find(struct ao_lisp_frame *frame, int top, ao_poly atom)
+{
+	int l = 0;
+	int r = top - 1;
+	while (l <= r) {
+		int m = (l + r) >> 1;
+		if (frame->vals[m].atom < atom)
+			l = m + 1;
+		else
+			r = m - 1;
+	}
+	return l;
+}
+
+ao_poly *
+ao_lisp_frame_ref(struct ao_lisp_frame *frame, ao_poly atom)
+{
+	int l = ao_lisp_frame_find(frame, frame->num, atom);
+
+	if (l >= frame->num)
+		return NULL;
+
+	if (frame->vals[l].atom != atom)
+		return NULL;
+	return &frame->vals[l].val;
+}
+
+int
+ao_lisp_frame_set(struct ao_lisp_frame *frame, ao_poly atom, ao_poly val)
+{
+	while (frame) {
+		if (!AO_LISP_IS_CONST(frame)) {
+			ao_poly *ref = ao_lisp_frame_ref(frame, atom);
+			if (ref) {
+				*ref = val;
+				return 1;
+			}
+		}
+		frame = ao_lisp_poly_frame(frame->prev);
+	}
+	return 0;
+}
+
+ao_poly
+ao_lisp_frame_get(struct ao_lisp_frame *frame, ao_poly atom)
+{
+	while (frame) {
+		ao_poly *ref = ao_lisp_frame_ref(frame, atom);
+		if (ref)
+			return *ref;
+		frame = ao_lisp_poly_frame(frame->prev);
+	}
+	return AO_LISP_NIL;
+}
+
+struct ao_lisp_frame	*ao_lisp_frame_free_list[AO_LISP_FRAME_FREE];
+
+struct ao_lisp_frame *
+ao_lisp_frame_new(int num)
+{
+	struct ao_lisp_frame	*frame;
+
+	if (num < AO_LISP_FRAME_FREE && (frame = ao_lisp_frame_free_list[num]))
+		ao_lisp_frame_free_list[num] = ao_lisp_poly_frame(frame->prev);
+	else {
+		frame = ao_lisp_alloc(frame_num_size(num));
+		if (!frame)
+			return NULL;
+	}
+	frame->type = AO_LISP_FRAME;
+	frame->num = num;
+	frame->prev = AO_LISP_NIL;
+	memset(frame->vals, '\0', num * sizeof (struct ao_lisp_val));
+	return frame;
+}
+
+ao_poly
+ao_lisp_frame_mark(struct ao_lisp_frame *frame)
+{
+	if (!frame)
+		return AO_LISP_NIL;
+	frame->type |= AO_LISP_FRAME_MARK;
+	return ao_lisp_frame_poly(frame);
+}
+
+void
+ao_lisp_frame_free(struct ao_lisp_frame *frame)
+{
+	if (!ao_lisp_frame_marked(frame)) {
+		int	num = frame->num;
+		if (num < AO_LISP_FRAME_FREE) {
+			frame->prev = ao_lisp_frame_poly(ao_lisp_frame_free_list[num]);
+			ao_lisp_frame_free_list[num] = frame;
+		}
+	}
+}
+
+static struct ao_lisp_frame *
+ao_lisp_frame_realloc(struct ao_lisp_frame **frame_ref, int new_num)
+{
+	struct ao_lisp_frame	*frame = *frame_ref;
+	struct ao_lisp_frame	*new;
+	int			copy;
+
+	if (new_num == frame->num)
+		return frame;
+	new = ao_lisp_frame_new(new_num);
+	if (!new)
+		return NULL;
+	/*
+	 * Re-fetch the frame as it may have moved
+	 * during the allocation
+	 */
+	frame = *frame_ref;
+	copy = new_num;
+	if (copy > frame->num)
+		copy = frame->num;
+	memcpy(new->vals, frame->vals, copy * sizeof (struct ao_lisp_val));
+	new->prev = frame->prev;
+	ao_lisp_frame_free(frame);
+	return new;
+}
+
+void
+ao_lisp_frame_bind(struct ao_lisp_frame *frame, int num, ao_poly atom, ao_poly val)
+{
+	int l = ao_lisp_frame_find(frame, num, atom);
+
+	memmove(&frame->vals[l+1],
+		&frame->vals[l],
+		(num - l) * sizeof (struct ao_lisp_val));
+	frame->vals[l].atom = atom;
+	frame->vals[l].val = val;
+}
+
+int
+ao_lisp_frame_add(struct ao_lisp_frame **frame_ref, ao_poly atom, ao_poly val)
+{
+	struct ao_lisp_frame *frame = *frame_ref;
+	ao_poly *ref = frame ? ao_lisp_frame_ref(frame, atom) : NULL;
+
+	if (!ref) {
+		int f;
+		ao_lisp_poly_stash(0, atom);
+		ao_lisp_poly_stash(1, val);
+		if (frame) {
+			f = frame->num;
+			frame = ao_lisp_frame_realloc(frame_ref, f + 1);
+		} else {
+			f = 0;
+			frame = ao_lisp_frame_new(1);
+		}
+		if (!frame)
+			return 0;
+		*frame_ref = frame;
+		atom = ao_lisp_poly_fetch(0);
+		val = ao_lisp_poly_fetch(1);
+		ao_lisp_frame_bind(frame, frame->num - 1, atom, val);
+	} else
+		*ref = val;
+	return 1;
+}
diff --git a/src/lisp/ao_lisp_int.c b/src/lisp/ao_lisp_int.c
new file mode 100644
index 00000000..77f65e95
--- /dev/null
+++ b/src/lisp/ao_lisp_int.c
@@ -0,0 +1,22 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
+void
+ao_lisp_int_print(ao_poly p)
+{
+	int i = ao_lisp_poly_int(p);
+	printf("%d", i);
+}
diff --git a/src/lisp/ao_lisp_lambda.c b/src/lisp/ao_lisp_lambda.c
new file mode 100644
index 00000000..526863c5
--- /dev/null
+++ b/src/lisp/ao_lisp_lambda.c
@@ -0,0 +1,196 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "ao_lisp.h"
+
+int
+lambda_size(void *addr)
+{
+	(void) addr;
+	return sizeof (struct ao_lisp_lambda);
+}
+
+void
+lambda_mark(void *addr)
+{
+	struct ao_lisp_lambda	*lambda = addr;
+
+	ao_lisp_poly_mark(lambda->code, 0);
+	ao_lisp_poly_mark(lambda->frame, 0);
+}
+
+void
+lambda_move(void *addr)
+{
+	struct ao_lisp_lambda	*lambda = addr;
+
+	ao_lisp_poly_move(&lambda->code, 0);
+	ao_lisp_poly_move(&lambda->frame, 0);
+}
+
+const struct ao_lisp_type ao_lisp_lambda_type = {
+	.size = lambda_size,
+	.mark = lambda_mark,
+	.move = lambda_move,
+	.name = "lambda",
+};
+
+void
+ao_lisp_lambda_print(ao_poly poly)
+{
+	struct ao_lisp_lambda	*lambda = ao_lisp_poly_lambda(poly);
+	struct ao_lisp_cons	*cons = ao_lisp_poly_cons(lambda->code);
+
+	printf("(");
+	printf("%s", ao_lisp_args_name(lambda->args));
+	while (cons) {
+		printf(" ");
+		ao_lisp_poly_print(cons->car);
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+	printf(")");
+}
+
+ao_poly
+ao_lisp_lambda_alloc(struct ao_lisp_cons *code, int args)
+{
+	ao_lisp_cons_stash(0, code);
+	struct ao_lisp_lambda	*lambda = ao_lisp_alloc(sizeof (struct ao_lisp_lambda));
+	code = ao_lisp_cons_fetch(0);
+	struct ao_lisp_cons	*arg;
+	int			f;
+
+	if (!lambda)
+		return AO_LISP_NIL;
+
+	if (!ao_lisp_check_argt(_ao_lisp_atom_lambda, code, 0, AO_LISP_CONS, 1))
+		return AO_LISP_NIL;
+	f = 0;
+	arg = ao_lisp_poly_cons(ao_lisp_arg(code, 0));
+	while (arg) {
+		if (ao_lisp_poly_type(arg->car) != AO_LISP_ATOM)
+			return ao_lisp_error(AO_LISP_INVALID, "formal %d is not an atom", f);
+		arg = ao_lisp_poly_cons(arg->cdr);
+		f++;
+	}
+
+	lambda->type = AO_LISP_LAMBDA;
+	lambda->args = args;
+	lambda->code = ao_lisp_cons_poly(code);
+	lambda->frame = ao_lisp_frame_mark(ao_lisp_frame_current);
+	DBGI("build frame: "); DBG_POLY(lambda->frame); DBG("\n");
+	DBG_STACK();
+	return ao_lisp_lambda_poly(lambda);
+}
+
+ao_poly
+ao_lisp_lambda(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_lambda_alloc(cons, AO_LISP_FUNC_LAMBDA);
+}
+
+ao_poly
+ao_lisp_lexpr(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_lambda_alloc(cons, AO_LISP_FUNC_LEXPR);
+}
+
+ao_poly
+ao_lisp_nlambda(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_lambda_alloc(cons, AO_LISP_FUNC_NLAMBDA);
+}
+
+ao_poly
+ao_lisp_macro(struct ao_lisp_cons *cons)
+{
+	return ao_lisp_lambda_alloc(cons, AO_LISP_FUNC_MACRO);
+}
+
+ao_poly
+ao_lisp_lambda_eval(void)
+{
+	struct ao_lisp_lambda	*lambda = ao_lisp_poly_lambda(ao_lisp_v);
+	struct ao_lisp_cons	*cons = ao_lisp_poly_cons(ao_lisp_stack->values);
+	struct ao_lisp_cons	*code = ao_lisp_poly_cons(lambda->code);
+	struct ao_lisp_cons	*args = ao_lisp_poly_cons(ao_lisp_arg(code, 0));
+	struct ao_lisp_frame	*next_frame;
+	int			args_wanted;
+	int			args_provided;
+	int			f;
+	struct ao_lisp_cons	*vals;
+
+	DBGI("lambda "); DBG_POLY(ao_lisp_lambda_poly(lambda)); DBG("\n");
+
+	args_wanted = ao_lisp_cons_length(args);
+
+	/* Create a frame to hold the variables
+	 */
+	args_provided = ao_lisp_cons_length(cons) - 1;
+	if (lambda->args == AO_LISP_FUNC_LAMBDA) {
+		if (args_wanted != args_provided)
+			return ao_lisp_error(AO_LISP_INVALID, "need %d args, got %d", args_wanted, args_provided);
+	} else {
+		if (args_provided < args_wanted - 1)
+			return ao_lisp_error(AO_LISP_INVALID, "need at least %d args, got %d", args_wanted, args_provided);
+	}
+
+	next_frame = ao_lisp_frame_new(args_wanted);
+
+	/* Re-fetch all of the values in case something moved */
+	lambda = ao_lisp_poly_lambda(ao_lisp_v);
+	cons = ao_lisp_poly_cons(ao_lisp_stack->values);
+	code = ao_lisp_poly_cons(lambda->code);
+	args = ao_lisp_poly_cons(ao_lisp_arg(code, 0));
+	vals = ao_lisp_poly_cons(cons->cdr);
+
+	next_frame->prev = lambda->frame;
+	ao_lisp_frame_current = next_frame;
+	ao_lisp_stack->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
+
+	switch (lambda->args) {
+	case AO_LISP_FUNC_LAMBDA:
+		for (f = 0; f < args_wanted; f++) {
+			DBGI("bind "); DBG_POLY(args->car); DBG(" = "); DBG_POLY(vals->car); DBG("\n");
+			ao_lisp_frame_bind(next_frame, f, args->car, vals->car);
+			args = ao_lisp_poly_cons(args->cdr);
+			vals = ao_lisp_poly_cons(vals->cdr);
+		}
+		if (!ao_lisp_stack_marked(ao_lisp_stack))
+			ao_lisp_cons_free(cons);
+		cons = NULL;
+		break;
+	case AO_LISP_FUNC_LEXPR:
+	case AO_LISP_FUNC_NLAMBDA:
+	case AO_LISP_FUNC_MACRO:
+		for (f = 0; f < args_wanted - 1; f++) {
+			DBGI("bind "); DBG_POLY(args->car); DBG(" = "); DBG_POLY(vals->car); DBG("\n");
+			ao_lisp_frame_bind(next_frame, f, args->car, vals->car);
+			args = ao_lisp_poly_cons(args->cdr);
+			vals = ao_lisp_poly_cons(vals->cdr);
+		}
+		DBGI("bind "); DBG_POLY(args->car); DBG(" = "); DBG_POLY(ao_lisp_cons_poly(vals)); DBG("\n");
+		ao_lisp_frame_bind(next_frame, f, args->car, ao_lisp_cons_poly(vals));
+		break;
+	default:
+		break;
+	}
+	DBGI("eval frame: "); DBG_POLY(ao_lisp_frame_poly(next_frame)); DBG("\n");
+	DBG_STACK();
+	DBGI("eval code: "); DBG_POLY(code->cdr); DBG("\n");
+	return code->cdr;
+}
diff --git a/src/lisp/ao_lisp_lex.c b/src/lisp/ao_lisp_lex.c
new file mode 100644
index 00000000..fe7c47f4
--- /dev/null
+++ b/src/lisp/ao_lisp_lex.c
@@ -0,0 +1,16 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
diff --git a/src/lisp/ao_lisp_make_const.c b/src/lisp/ao_lisp_make_const.c
new file mode 100644
index 00000000..49f989e6
--- /dev/null
+++ b/src/lisp/ao_lisp_make_const.c
@@ -0,0 +1,423 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+#include <stdlib.h>
+#include <ctype.h>
+#include <unistd.h>
+#include <getopt.h>
+
+static struct ao_lisp_builtin *
+ao_lisp_make_builtin(enum ao_lisp_builtin_id func, int args) {
+	struct ao_lisp_builtin *b = ao_lisp_alloc(sizeof (struct ao_lisp_builtin));
+
+	b->type = AO_LISP_BUILTIN;
+	b->func = func;
+	b->args = args;
+	return b;
+}
+
+struct builtin_func {
+	char	*name;
+	int	args;
+	int	func;
+};
+
+struct builtin_func funcs[] = {
+	{ .name = "eval",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_eval },
+	{ .name = "read",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_read },
+	{ .name = "lambda",	.args = AO_LISP_FUNC_NLAMBDA,	.func = builtin_lambda },
+	{ .name = "lexpr",	.args = AO_LISP_FUNC_NLAMBDA,	.func = builtin_lexpr },
+	{ .name = "nlambda",	.args = AO_LISP_FUNC_NLAMBDA,	.func = builtin_nlambda },
+	{ .name = "macro",	.args = AO_LISP_FUNC_NLAMBDA,	.func = builtin_macro },
+	{ .name = "car",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_car },
+	{ .name = "cdr",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_cdr },
+	{ .name = "cons",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_cons },
+	{ .name = "last",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_last },
+	{ .name = "length",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_length },
+	{ .name = "quote",	.args = AO_LISP_FUNC_NLAMBDA,	.func = builtin_quote },
+	{ .name = "set",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_set },
+	{ .name = "setq",	.args = AO_LISP_FUNC_MACRO,	.func = builtin_setq },
+	{ .name = "cond",	.args = AO_LISP_FUNC_NLAMBDA,	.func = builtin_cond },
+	{ .name = "progn",	.args = AO_LISP_FUNC_NLAMBDA,	.func = builtin_progn },
+	{ .name = "while",	.args = AO_LISP_FUNC_NLAMBDA,	.func = builtin_while },
+	{ .name = "print",	.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_print },
+	{ .name = "patom",	.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_patom },
+	{ .name = "+",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_plus },
+	{ .name = "-",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_minus },
+	{ .name = "*",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_times },
+	{ .name = "/",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_divide },
+	{ .name = "%",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_mod },
+	{ .name = "=",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_equal },
+	{ .name = "<",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_less },
+	{ .name = ">",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_greater },
+	{ .name = "<=",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_less_equal },
+	{ .name = ">=",		.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_greater_equal },
+	{ .name = "pack",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_pack },
+	{ .name = "unpack",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_unpack },
+	{ .name = "flush",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_flush },
+	{ .name = "delay",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_delay },
+	{ .name = "led",	.args = AO_LISP_FUNC_F_LEXPR,	.func = builtin_led },
+	{ .name = "save",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_save },
+	{ .name = "restore",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_restore },
+	{ .name = "call/cc",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_call_cc },
+	{ .name = "collect",	.args = AO_LISP_FUNC_F_LAMBDA,	.func = builtin_collect },
+};
+
+#define N_FUNC (sizeof funcs / sizeof funcs[0])
+
+struct ao_lisp_frame	*globals;
+
+static int
+is_atom(int offset)
+{
+	struct ao_lisp_atom *a;
+
+	for (a = ao_lisp_atoms; a; a = ao_lisp_poly_atom(a->next))
+		if (((uint8_t *) a->name - ao_lisp_const) == offset)
+			return strlen(a->name);
+	return 0;
+}
+
+#define AO_FEC_CRC_INIT	0xffff
+
+static inline uint16_t
+ao_fec_crc_byte(uint8_t byte, uint16_t crc)
+{
+	uint8_t	bit;
+
+	for (bit = 0; bit < 8; bit++) {
+		if (((crc & 0x8000) >> 8) ^ (byte & 0x80))
+			crc = (crc << 1) ^ 0x8005;
+		else
+			crc = (crc << 1);
+		byte <<= 1;
+	}
+	return crc;
+}
+
+uint16_t
+ao_fec_crc(const uint8_t *bytes, uint8_t len)
+{
+	uint16_t	crc = AO_FEC_CRC_INIT;
+
+	while (len--)
+		crc = ao_fec_crc_byte(*bytes++, crc);
+	return crc;
+}
+
+struct ao_lisp_macro_stack {
+	struct ao_lisp_macro_stack *next;
+	ao_poly	p;
+};
+
+struct ao_lisp_macro_stack *macro_stack;
+
+int
+ao_lisp_macro_push(ao_poly p)
+{
+	struct ao_lisp_macro_stack *m = macro_stack;
+
+	while (m) {
+		if (m->p == p)
+			return 1;
+		m = m->next;
+	}
+	m = malloc (sizeof (struct ao_lisp_macro_stack));
+	m->p = p;
+	m->next = macro_stack;
+	macro_stack = m;
+	return 0;
+}
+
+void
+ao_lisp_macro_pop(void)
+{
+	struct ao_lisp_macro_stack *m = macro_stack;
+
+	macro_stack = m->next;
+	free(m);
+}
+
+#define DBG_MACRO 0
+#if DBG_MACRO
+int macro_scan_depth;
+
+void indent(void)
+{
+	int i;
+	for (i = 0; i < macro_scan_depth; i++)
+		printf("  ");
+}
+#define MACRO_DEBUG(a)	a
+#else
+#define MACRO_DEBUG(a)
+#endif
+
+ao_poly
+ao_has_macro(ao_poly p);
+
+ao_poly
+ao_macro_test_get(ao_poly atom)
+{
+	ao_poly	*ref = ao_lisp_atom_ref(ao_lisp_frame_global, atom);
+	if (ref)
+		return *ref;
+	return AO_LISP_NIL;
+}
+
+ao_poly
+ao_is_macro(ao_poly p)
+{
+	struct ao_lisp_builtin	*builtin;
+	struct ao_lisp_lambda	*lambda;
+	ao_poly ret;
+
+	MACRO_DEBUG(indent(); printf ("is macro "); ao_lisp_poly_print(p); printf("\n"); ++macro_scan_depth);
+	switch (ao_lisp_poly_type(p)) {
+	case AO_LISP_ATOM:
+		if (ao_lisp_macro_push(p))
+			ret = AO_LISP_NIL;
+		else {
+			if (ao_is_macro(ao_macro_test_get(p)))
+				ret = p;
+			else
+				ret = AO_LISP_NIL;
+			ao_lisp_macro_pop();
+		}
+		break;
+	case AO_LISP_CONS:
+		ret = ao_has_macro(p);
+		break;
+	case AO_LISP_BUILTIN:
+		builtin = ao_lisp_poly_builtin(p);
+		if ((builtin->args & AO_LISP_FUNC_MASK) == AO_LISP_FUNC_MACRO)
+			ret = p;
+		else
+			ret = 0;
+		break;
+
+	case AO_LISP_LAMBDA:
+		lambda = ao_lisp_poly_lambda(p);
+		if (lambda->args == AO_LISP_FUNC_MACRO)
+			ret = p;
+		else
+			ret = ao_has_macro(lambda->code);
+		break;
+	default:
+		ret = AO_LISP_NIL;
+		break;
+	}
+	MACRO_DEBUG(--macro_scan_depth;	indent(); printf ("... "); ao_lisp_poly_print(ret); printf("\n"));
+	return ret;
+}
+
+ao_poly
+ao_has_macro(ao_poly p)
+{
+	struct ao_lisp_cons	*cons;
+	struct ao_lisp_lambda	*lambda;
+	ao_poly			m;
+
+	if (p == AO_LISP_NIL)
+		return AO_LISP_NIL;
+
+	MACRO_DEBUG(indent(); printf("has macro "); ao_lisp_poly_print(p); printf("\n"); ++macro_scan_depth);
+	switch (ao_lisp_poly_type(p)) {
+	case AO_LISP_LAMBDA:
+		lambda = ao_lisp_poly_lambda(p);
+		p = ao_has_macro(lambda->code);
+		break;
+	case AO_LISP_CONS:
+		cons = ao_lisp_poly_cons(p);
+		if ((p = ao_is_macro(cons->car)))
+			break;
+
+		cons = ao_lisp_poly_cons(cons->cdr);
+		p = AO_LISP_NIL;
+		while (cons) {
+			m = ao_has_macro(cons->car);
+			if (m) {
+				p = m;
+				break;
+			}
+			cons = ao_lisp_poly_cons(cons->cdr);
+		}
+		break;
+
+	default:
+		p = AO_LISP_NIL;
+		break;
+	}
+	MACRO_DEBUG(--macro_scan_depth;	indent(); printf("... "); ao_lisp_poly_print(p); printf("\n"));
+	return p;
+}
+
+int
+ao_lisp_read_eval_abort(void)
+{
+	ao_poly	in, out = AO_LISP_NIL;
+	for(;;) {
+		in = ao_lisp_read();
+		if (in == _ao_lisp_atom_eof)
+			break;
+		out = ao_lisp_eval(in);
+		if (ao_lisp_exception)
+			return 0;
+		ao_lisp_poly_print(out);
+		putchar ('\n');
+	}
+	return 1;
+}
+
+static FILE	*in;
+static FILE	*out;
+
+int
+ao_lisp_getc(void)
+{
+	return getc(in);
+}
+
+static const struct option options[] = {
+	{ .name = "out", .has_arg = 1, .val = 'o' },
+	{ 0, 0, 0, 0 }
+};
+
+static void usage(char *program)
+{
+	fprintf(stderr, "usage: %s [--out=<output>] [input]\n", program);
+	exit(1);
+}
+
+int
+main(int argc, char **argv)
+{
+	int	f, o;
+	ao_poly	val;
+	struct ao_lisp_atom	*a;
+	struct ao_lisp_builtin	*b;
+	int	in_atom = 0;
+	char	*out_name = NULL;
+	int	c;
+
+	in = stdin;
+	out = stdout;
+
+	while ((c = getopt_long(argc, argv, "o:", options, NULL)) != -1) {
+		switch (c) {
+		case 'o':
+			out_name = optarg;
+			break;
+		default:
+			usage(argv[0]);
+			break;
+		}
+	}
+
+	for (f = 0; f < (int) N_FUNC; f++) {
+		b = ao_lisp_make_builtin(funcs[f].func, funcs[f].args);
+		a = ao_lisp_atom_intern(funcs[f].name);
+		ao_lisp_atom_set(ao_lisp_atom_poly(a),
+				 ao_lisp_builtin_poly(b));
+	}
+
+	/* boolean constants */
+	ao_lisp_atom_set(ao_lisp_atom_poly(ao_lisp_atom_intern("nil")),
+			 AO_LISP_NIL);
+	a = ao_lisp_atom_intern("t");
+	ao_lisp_atom_set(ao_lisp_atom_poly(a),
+			 ao_lisp_atom_poly(a));
+
+	/* end of file value */
+	a = ao_lisp_atom_intern("eof");
+	ao_lisp_atom_set(ao_lisp_atom_poly(a),
+			 ao_lisp_atom_poly(a));
+
+	if (argv[optind]){
+		in = fopen(argv[optind], "r");
+		if (!in) {
+			perror(argv[optind]);
+			exit(1);
+		}
+	}
+	if (!ao_lisp_read_eval_abort()) {
+		fprintf(stderr, "eval failed\n");
+		exit(1);
+	}
+
+	/* Reduce to referenced values */
+	ao_lisp_collect(AO_LISP_COLLECT_FULL);
+
+	for (f = 0; f < ao_lisp_frame_global->num; f++) {
+		val = ao_has_macro(ao_lisp_frame_global->vals[f].val);
+		if (val != AO_LISP_NIL) {
+			printf("error: function %s contains unresolved macro: ",
+			       ao_lisp_poly_atom(ao_lisp_frame_global->vals[f].atom)->name);
+			ao_lisp_poly_print(val);
+			printf("\n");
+			exit(1);
+		}
+	}
+
+	if (out_name) {
+		out = fopen(out_name, "w");
+		if (!out) {
+			perror(out_name);
+			exit(1);
+		}
+	}
+
+	fprintf(out, "/* Generated file, do not edit */\n\n");
+
+	fprintf(out, "#define AO_LISP_POOL_CONST %d\n", ao_lisp_top);
+	fprintf(out, "extern const uint8_t ao_lisp_const[AO_LISP_POOL_CONST] __attribute__((aligned(4)));\n");
+	fprintf(out, "#define ao_builtin_atoms 0x%04x\n", ao_lisp_atom_poly(ao_lisp_atoms));
+	fprintf(out, "#define ao_builtin_frame 0x%04x\n", ao_lisp_frame_poly(ao_lisp_frame_global));
+	fprintf(out, "#define ao_lisp_const_checksum ((uint16_t) 0x%04x)\n", ao_fec_crc(ao_lisp_const, ao_lisp_top));
+
+
+	for (a = ao_lisp_atoms; a; a = ao_lisp_poly_atom(a->next)) {
+		char	*n = a->name, c;
+		fprintf(out, "#define _ao_lisp_atom_");
+		while ((c = *n++)) {
+			if (isalnum(c))
+				fprintf(out, "%c", c);
+			else
+				fprintf(out, "%02x", c);
+		}
+		fprintf(out, "  0x%04x\n", ao_lisp_atom_poly(a));
+	}
+	fprintf(out, "#ifdef AO_LISP_CONST_BITS\n");
+	fprintf(out, "const uint8_t ao_lisp_const[AO_LISP_POOL_CONST] __attribute((aligned(4))) = {");
+	for (o = 0; o < ao_lisp_top; o++) {
+		uint8_t	c;
+		if ((o & 0xf) == 0)
+			fprintf(out, "\n\t");
+		else
+			fprintf(out, " ");
+		c = ao_lisp_const[o];
+		if (!in_atom)
+			in_atom = is_atom(o);
+		if (in_atom) {
+			fprintf(out, " '%c',", c);
+			in_atom--;
+		} else {
+			fprintf(out, "0x%02x,", c);
+		}
+	}
+	fprintf(out, "\n};\n");
+	fprintf(out, "#endif /* AO_LISP_CONST_BITS */\n");
+	exit(0);
+}
diff --git a/src/lisp/ao_lisp_mem.c b/src/lisp/ao_lisp_mem.c
new file mode 100644
index 00000000..d067ea07
--- /dev/null
+++ b/src/lisp/ao_lisp_mem.c
@@ -0,0 +1,880 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#define AO_LISP_CONST_BITS
+
+#include "ao_lisp.h"
+#include <stdio.h>
+
+#ifdef AO_LISP_MAKE_CONST
+
+/*
+ * When building the constant table, it is the
+ * pool for allocations.
+ */
+
+#include <stdlib.h>
+uint8_t ao_lisp_const[AO_LISP_POOL_CONST] __attribute__((aligned(4)));
+#define ao_lisp_pool ao_lisp_const
+#undef AO_LISP_POOL
+#define AO_LISP_POOL AO_LISP_POOL_CONST
+
+#else
+
+uint8_t	ao_lisp_pool[AO_LISP_POOL + AO_LISP_POOL_EXTRA] __attribute__((aligned(4)));
+
+#endif
+
+#ifndef DBG_MEM_STATS
+#define DBG_MEM_STATS	DBG_MEM
+#endif
+
+#if DBG_MEM
+int dbg_move_depth;
+int dbg_mem = DBG_MEM_START;
+int dbg_validate = 0;
+
+struct ao_lisp_record {
+	struct ao_lisp_record		*next;
+	const struct ao_lisp_type	*type;
+	void				*addr;
+	int				size;
+};
+
+static struct ao_lisp_record	*record_head, **record_tail;
+
+static void
+ao_lisp_record_free(struct ao_lisp_record *record)
+{
+	while (record) {
+		struct ao_lisp_record *next = record->next;
+		free(record);
+		record = next;
+	}
+}
+
+static void
+ao_lisp_record_reset(void)
+{
+	ao_lisp_record_free(record_head);
+	record_head = NULL;
+	record_tail = &record_head;
+}
+
+static void
+ao_lisp_record(const struct ao_lisp_type	*type,
+	       void				*addr,
+	       int				size)
+{
+	struct ao_lisp_record	*r = malloc(sizeof (struct ao_lisp_record));
+
+	r->next = NULL;
+	r->type = type;
+	r->addr = addr;
+	r->size = size;
+	*record_tail = r;
+	record_tail = &r->next;
+}
+
+static struct ao_lisp_record *
+ao_lisp_record_save(void)
+{
+	struct ao_lisp_record *r = record_head;
+
+	record_head = NULL;
+	record_tail = &record_head;
+	return r;
+}
+
+static void
+ao_lisp_record_compare(char *where,
+		       struct ao_lisp_record *a,
+		       struct ao_lisp_record *b)
+{
+	while (a && b) {
+		if (a->type != b->type || a->size != b->size) {
+			printf("%s record difers %d %s %d -> %d %s %d\n",
+			       where,
+			       MDBG_OFFSET(a->addr),
+			       a->type->name,
+			       a->size,
+			       MDBG_OFFSET(b->addr),
+			       b->type->name,
+			       b->size);
+			ao_lisp_abort();
+		}
+		a = a->next;
+		b = b->next;
+	}
+	if (a) {
+		printf("%s record differs %d %s %d -> NULL\n",
+		       where,
+		       MDBG_OFFSET(a->addr),
+		       a->type->name,
+		       a->size);
+		ao_lisp_abort();
+	}
+	if (b) {
+		printf("%s record differs NULL -> %d %s %d\n",
+		       where,
+		       MDBG_OFFSET(b->addr),
+		       b->type->name,
+		       b->size);
+		ao_lisp_abort();
+	}
+}
+
+#else
+#define ao_lisp_record_reset()
+#endif
+
+uint8_t	ao_lisp_exception;
+
+struct ao_lisp_root {
+	const struct ao_lisp_type	*type;
+	void				**addr;
+};
+
+static struct ao_lisp_cons 	*save_cons[2];
+static char			*save_string[2];
+static ao_poly			save_poly[3];
+
+static const struct ao_lisp_root	ao_lisp_root[] = {
+	{
+		.type = &ao_lisp_cons_type,
+		.addr = (void **) &save_cons[0],
+	},
+	{
+		.type = &ao_lisp_cons_type,
+		.addr = (void **) &save_cons[1],
+	},
+	{
+		.type = &ao_lisp_string_type,
+		.addr = (void **) &save_string[0],
+	},
+	{
+		.type = &ao_lisp_string_type,
+		.addr = (void **) &save_string[1],
+	},
+	{
+		.type = NULL,
+		.addr = (void **) (void *) &save_poly[0]
+	},
+	{
+		.type = NULL,
+		.addr = (void **) (void *) &save_poly[1]
+	},
+	{
+		.type = NULL,
+		.addr = (void **) (void *) &save_poly[2]
+	},
+	{
+		.type = &ao_lisp_atom_type,
+		.addr = (void **) &ao_lisp_atoms
+	},
+	{
+		.type = &ao_lisp_frame_type,
+		.addr = (void **) &ao_lisp_frame_global,
+	},
+	{
+		.type = &ao_lisp_frame_type,
+		.addr = (void **) &ao_lisp_frame_current,
+	},
+	{
+		.type = &ao_lisp_stack_type,
+		.addr = (void **) &ao_lisp_stack,
+	},
+	{
+		.type = NULL,
+		.addr = (void **) (void *) &ao_lisp_v,
+	},
+	{
+		.type = &ao_lisp_cons_type,
+		.addr = (void **) &ao_lisp_read_cons,
+	},
+	{
+		.type = &ao_lisp_cons_type,
+		.addr = (void **) &ao_lisp_read_cons_tail,
+	},
+	{
+		.type = &ao_lisp_cons_type,
+		.addr = (void **) &ao_lisp_read_stack,
+	},
+};
+
+#define AO_LISP_ROOT	(sizeof (ao_lisp_root) / sizeof (ao_lisp_root[0]))
+
+static const void ** const ao_lisp_cache[] = {
+	(const void **) &ao_lisp_cons_free_list,
+	(const void **) &ao_lisp_stack_free_list,
+	(const void **) &ao_lisp_frame_free_list[0],
+	(const void **) &ao_lisp_frame_free_list[1],
+	(const void **) &ao_lisp_frame_free_list[2],
+	(const void **) &ao_lisp_frame_free_list[3],
+	(const void **) &ao_lisp_frame_free_list[4],
+	(const void **) &ao_lisp_frame_free_list[5],
+};
+
+#if AO_LISP_FRAME_FREE != 6
+#error Unexpected AO_LISP_FRAME_FREE value
+#endif
+
+#define AO_LISP_CACHE	(sizeof (ao_lisp_cache) / sizeof (ao_lisp_cache[0]))
+
+#define AO_LISP_BUSY_SIZE	((AO_LISP_POOL + 31) / 32)
+
+static uint8_t	ao_lisp_busy[AO_LISP_BUSY_SIZE];
+static uint8_t	ao_lisp_cons_note[AO_LISP_BUSY_SIZE];
+static uint8_t	ao_lisp_cons_last[AO_LISP_BUSY_SIZE];
+static uint8_t	ao_lisp_cons_noted;
+
+uint16_t	ao_lisp_top;
+
+struct ao_lisp_chunk {
+	uint16_t		old_offset;
+	union {
+		uint16_t	size;
+		uint16_t	new_offset;
+	};
+};
+
+#define AO_LISP_NCHUNK	64
+
+static struct ao_lisp_chunk ao_lisp_chunk[AO_LISP_NCHUNK];
+
+/* Offset of an address within the pool. */
+static inline uint16_t pool_offset(void *addr) {
+#if DBG_MEM
+	if (!AO_LISP_IS_POOL(addr))
+		ao_lisp_abort();
+#endif
+	return ((uint8_t *) addr) - ao_lisp_pool;
+}
+
+static inline void mark(uint8_t *tag, int offset) {
+	int	byte = offset >> 5;
+	int	bit = (offset >> 2) & 7;
+	tag[byte] |= (1 << bit);
+}
+
+static inline void clear(uint8_t *tag, int offset) {
+	int	byte = offset >> 5;
+	int	bit = (offset >> 2) & 7;
+	tag[byte] &= ~(1 << bit);
+}
+
+static inline int busy(uint8_t *tag, int offset) {
+	int	byte = offset >> 5;
+	int	bit = (offset >> 2) & 7;
+	return (tag[byte] >> bit) & 1;
+}
+
+static inline int min(int a, int b) { return a < b ? a : b; }
+static inline int max(int a, int b) { return a > b ? a : b; }
+
+static inline int limit(int offset) {
+	return min(AO_LISP_POOL, max(offset, 0));
+}
+
+static void
+note_cons(uint16_t offset)
+{
+	MDBG_MOVE("note cons %d\n", offset);
+	ao_lisp_cons_noted = 1;
+	mark(ao_lisp_cons_note, offset);
+}
+
+static uint16_t	chunk_low, chunk_high;
+static uint16_t	chunk_first, chunk_last;
+
+static int
+find_chunk(uint16_t offset)
+{
+	int l, r;
+	/* Binary search for the location */
+	l = chunk_first;
+	r = chunk_last - 1;
+	while (l <= r) {
+		int m = (l + r) >> 1;
+		if (ao_lisp_chunk[m].old_offset < offset)
+			l = m + 1;
+		else
+			r = m - 1;
+	}
+	return l;
+}
+
+static void
+note_chunk(uint16_t offset, uint16_t size)
+{
+	int l;
+
+	if (offset < chunk_low || chunk_high <= offset)
+		return;
+
+	l = find_chunk(offset);
+
+	/*
+	 * The correct location is always in 'l', with r = l-1 being
+	 * the entry before the right one
+	 */
+
+#if DBG_MEM
+	/* Off the right side */
+	if (l >= AO_LISP_NCHUNK)
+		ao_lisp_abort();
+
+	/* Off the left side */
+	if (l == 0 && chunk_last && offset > ao_lisp_chunk[0].old_offset)
+		ao_lisp_abort();
+#endif
+
+	/* Shuffle existing entries right */
+	int end = min(AO_LISP_NCHUNK, chunk_last + 1);
+
+	memmove(&ao_lisp_chunk[l+1],
+		&ao_lisp_chunk[l],
+		(end - (l+1)) * sizeof (struct ao_lisp_chunk));
+
+	/* Add new entry */
+	ao_lisp_chunk[l].old_offset = offset;
+	ao_lisp_chunk[l].size = size;
+
+	/* Increment the number of elements up to the size of the array */
+	if (chunk_last < AO_LISP_NCHUNK)
+		chunk_last++;
+
+	/* Set the top address if the array is full */
+	if (chunk_last == AO_LISP_NCHUNK)
+		chunk_high = ao_lisp_chunk[AO_LISP_NCHUNK-1].old_offset +
+			ao_lisp_chunk[AO_LISP_NCHUNK-1].size;
+}
+
+static void
+reset_chunks(void)
+{
+	chunk_high = ao_lisp_top;
+	chunk_last = 0;
+	chunk_first = 0;
+}
+
+/*
+ * Walk all referenced objects calling functions on each one
+ */
+
+static void
+walk(int (*visit_addr)(const struct ao_lisp_type *type, void **addr),
+     int (*visit_poly)(ao_poly *p, uint8_t do_note_cons))
+{
+	int i;
+
+	ao_lisp_record_reset();
+	memset(ao_lisp_busy, '\0', sizeof (ao_lisp_busy));
+	memset(ao_lisp_cons_note, '\0', sizeof (ao_lisp_cons_note));
+	ao_lisp_cons_noted = 0;
+	for (i = 0; i < (int) AO_LISP_ROOT; i++) {
+		if (ao_lisp_root[i].type) {
+			void **a = ao_lisp_root[i].addr, *v;
+			if (a && (v = *a)) {
+				MDBG_MOVE("root ptr %d\n", MDBG_OFFSET(v));
+				visit_addr(ao_lisp_root[i].type, a);
+			}
+		} else {
+			ao_poly *a = (ao_poly *) ao_lisp_root[i].addr, p;
+			if (a && (p = *a)) {
+				MDBG_MOVE("root poly %d\n", MDBG_OFFSET(ao_lisp_ref(p)));
+				visit_poly(a, 0);
+			}
+		}
+	}
+	while (ao_lisp_cons_noted) {
+		memcpy(ao_lisp_cons_last, ao_lisp_cons_note, sizeof (ao_lisp_cons_note));
+		memset(ao_lisp_cons_note, '\0', sizeof (ao_lisp_cons_note));
+		ao_lisp_cons_noted = 0;
+		for (i = 0; i < AO_LISP_POOL; i += 4) {
+			if (busy(ao_lisp_cons_last, i)) {
+				void *v = ao_lisp_pool + i;
+				MDBG_MOVE("root cons %d\n", MDBG_OFFSET(v));
+				visit_addr(&ao_lisp_cons_type, &v);
+			}
+		}
+	}
+}
+
+#if MDBG_DUMP
+static void
+dump_busy(void)
+{
+	int	i;
+	MDBG_MOVE("busy:");
+	for (i = 0; i < ao_lisp_top; i += 4) {
+		if ((i & 0xff) == 0) {
+			MDBG_MORE("\n");
+			MDBG_MOVE("%s", "");
+		}
+		else if ((i & 0x1f) == 0)
+			MDBG_MORE(" ");
+		if (busy(ao_lisp_busy, i))
+			MDBG_MORE("*");
+		else
+			MDBG_MORE("-");
+	}
+	MDBG_MORE ("\n");
+}
+#define DUMP_BUSY()	dump_busy()
+#else
+#define DUMP_BUSY()
+#endif
+
+static const struct ao_lisp_type const *ao_lisp_types[AO_LISP_NUM_TYPE] = {
+	[AO_LISP_CONS] = &ao_lisp_cons_type,
+	[AO_LISP_INT] = NULL,
+	[AO_LISP_STRING] = &ao_lisp_string_type,
+	[AO_LISP_OTHER] = (void *) 0x1,
+	[AO_LISP_ATOM] = &ao_lisp_atom_type,
+	[AO_LISP_BUILTIN] = &ao_lisp_builtin_type,
+	[AO_LISP_FRAME] = &ao_lisp_frame_type,
+	[AO_LISP_LAMBDA] = &ao_lisp_lambda_type,
+	[AO_LISP_STACK] = &ao_lisp_stack_type,
+};
+
+static int
+ao_lisp_mark_ref(const struct ao_lisp_type *type, void **ref)
+{
+	return ao_lisp_mark(type, *ref);
+}
+
+static int
+ao_lisp_poly_mark_ref(ao_poly *p, uint8_t do_note_cons)
+{
+	return ao_lisp_poly_mark(*p, do_note_cons);
+}
+
+#if DBG_MEM_STATS
+int ao_lisp_collects[2];
+int ao_lisp_freed[2];
+int ao_lisp_loops[2];
+#endif
+
+int ao_lisp_last_top;
+
+int
+ao_lisp_collect(uint8_t style)
+{
+	int	i;
+	int	top;
+#if DBG_MEM_STATS
+	int	loops = 0;
+#endif
+#if DBG_MEM
+	struct ao_lisp_record	*mark_record = NULL, *move_record = NULL;
+
+	MDBG_MOVE("collect %d\n", ao_lisp_collects[style]);
+#endif
+
+	/* The first time through, we're doing a full collect */
+	if (ao_lisp_last_top == 0)
+		style = AO_LISP_COLLECT_FULL;
+
+	/* Clear references to all caches */
+	for (i = 0; i < (int) AO_LISP_CACHE; i++)
+		*ao_lisp_cache[i] = NULL;
+	if (style == AO_LISP_COLLECT_FULL) {
+		chunk_low = top = 0;
+	} else {
+		chunk_low = top = ao_lisp_last_top;
+	}
+	for (;;) {
+#if DBG_MEM_STATS
+		loops++;
+#endif
+		MDBG_MOVE("move chunks from %d to %d\n", chunk_low, top);
+		/* Find the sizes of the first chunk of objects to move */
+		reset_chunks();
+		walk(ao_lisp_mark_ref, ao_lisp_poly_mark_ref);
+#if DBG_MEM
+
+		ao_lisp_record_free(mark_record);
+		mark_record = ao_lisp_record_save();
+		if (mark_record && move_record)
+			ao_lisp_record_compare("mark", move_record, mark_record);
+#endif
+
+		DUMP_BUSY();
+
+		/* Find the first moving object */
+		for (i = 0; i < chunk_last; i++) {
+			uint16_t	size = ao_lisp_chunk[i].size;
+
+#if DBG_MEM
+			if (!size)
+				ao_lisp_abort();
+#endif
+
+			if (ao_lisp_chunk[i].old_offset > top)
+				break;
+
+			MDBG_MOVE("chunk %d %d not moving\n",
+				  ao_lisp_chunk[i].old_offset,
+				  ao_lisp_chunk[i].size);
+#if DBG_MEM
+			if (ao_lisp_chunk[i].old_offset != top)
+				ao_lisp_abort();
+#endif
+			top += size;
+		}
+
+		/*
+		 * Limit amount of chunk array used in mapping moves
+		 * to the active region
+		 */
+		chunk_first = i;
+		chunk_low = ao_lisp_chunk[i].old_offset;
+
+		/* Copy all of the objects */
+		for (; i < chunk_last; i++) {
+			uint16_t	size = ao_lisp_chunk[i].size;
+
+#if DBG_MEM
+			if (!size)
+				ao_lisp_abort();
+#endif
+
+			MDBG_MOVE("chunk %d %d -> %d\n",
+				  ao_lisp_chunk[i].old_offset,
+				  size,
+				  top);
+			ao_lisp_chunk[i].new_offset = top;
+
+			memmove(&ao_lisp_pool[top],
+				&ao_lisp_pool[ao_lisp_chunk[i].old_offset],
+				size);
+
+			top += size;
+		}
+
+		if (chunk_first < chunk_last) {
+			/* Relocate all references to the objects */
+			walk(ao_lisp_move, ao_lisp_poly_move);
+
+#if DBG_MEM
+			ao_lisp_record_free(move_record);
+			move_record = ao_lisp_record_save();
+			if (mark_record && move_record)
+				ao_lisp_record_compare("move", mark_record, move_record);
+#endif
+		}
+
+		/* If we ran into the end of the heap, then
+		 * there's no need to keep walking
+		 */
+		if (chunk_last != AO_LISP_NCHUNK)
+			break;
+
+		/* Next loop starts right above this loop */
+		chunk_low = chunk_high;
+	}
+
+#if DBG_MEM_STATS
+	/* Collect stats */
+	++ao_lisp_collects[style];
+	ao_lisp_freed[style] += ao_lisp_top - top;
+	ao_lisp_loops[style] += loops;
+#endif
+
+	ao_lisp_top = top;
+	if (style == AO_LISP_COLLECT_FULL)
+		ao_lisp_last_top = top;
+
+	MDBG_DO(memset(ao_lisp_chunk, '\0', sizeof (ao_lisp_chunk));
+		walk(ao_lisp_mark_ref, ao_lisp_poly_mark_ref));
+
+	return AO_LISP_POOL - ao_lisp_top;
+}
+
+/*
+ * Mark interfaces for objects
+ */
+
+/*
+ * Note a reference to memory and collect information about a few
+ * object sizes at a time
+ */
+
+int
+ao_lisp_mark_memory(const struct ao_lisp_type *type, void *addr)
+{
+	int offset;
+	if (!AO_LISP_IS_POOL(addr))
+		return 1;
+
+	offset = pool_offset(addr);
+	MDBG_MOVE("mark memory %d\n", MDBG_OFFSET(addr));
+	if (busy(ao_lisp_busy, offset)) {
+		MDBG_MOVE("already marked\n");
+		return 1;
+	}
+	mark(ao_lisp_busy, offset);
+	note_chunk(offset, ao_lisp_size(type, addr));
+	return 0;
+}
+
+/*
+ * Mark an object and all that it refereces
+ */
+int
+ao_lisp_mark(const struct ao_lisp_type *type, void *addr)
+{
+	int ret;
+	MDBG_MOVE("mark %d\n", MDBG_OFFSET(addr));
+	MDBG_MOVE_IN();
+	ret = ao_lisp_mark_memory(type, addr);
+	if (!ret) {
+		MDBG_MOVE("mark recurse\n");
+		type->mark(addr);
+	}
+	MDBG_MOVE_OUT();
+	return ret;
+}
+
+/*
+ * Mark an object, unless it is a cons cell and
+ * do_note_cons is set. In that case, just
+ * set a bit in the cons note array; those
+ * will be marked in a separate pass to avoid
+ * deep recursion in the collector
+ */
+int
+ao_lisp_poly_mark(ao_poly p, uint8_t do_note_cons)
+{
+	uint8_t type;
+	void	*addr;
+
+	type = ao_lisp_poly_base_type(p);
+
+	if (type == AO_LISP_INT)
+		return 1;
+
+	addr = ao_lisp_ref(p);
+	if (!AO_LISP_IS_POOL(addr))
+		return 1;
+
+	if (type == AO_LISP_CONS && do_note_cons) {
+		note_cons(pool_offset(addr));
+		return 1;
+	} else {
+		if (type == AO_LISP_OTHER)
+			type = ao_lisp_other_type(addr);
+
+		const struct ao_lisp_type *lisp_type = ao_lisp_types[type];
+#if DBG_MEM
+		if (!lisp_type)
+			ao_lisp_abort();
+#endif
+
+		return ao_lisp_mark(lisp_type, addr);
+	}
+}
+
+/*
+ * Find the current location of an object
+ * based on the original location. For unmoved
+ * objects, this is simple. For moved objects,
+ * go search for it
+ */
+
+static uint16_t
+move_map(uint16_t offset)
+{
+	int		l;
+
+	if (offset < chunk_low || chunk_high <= offset)
+		return offset;
+
+	l = find_chunk(offset);
+
+#if DBG_MEM
+	if (ao_lisp_chunk[l].old_offset != offset)
+		ao_lisp_abort();
+#endif
+	return ao_lisp_chunk[l].new_offset;
+}
+
+int
+ao_lisp_move_memory(const struct ao_lisp_type *type, void **ref)
+{
+	void		*addr = *ref;
+	uint16_t	offset, orig_offset;
+
+	if (!AO_LISP_IS_POOL(addr))
+		return 1;
+
+	(void) type;
+
+	MDBG_MOVE("move memory %d\n", MDBG_OFFSET(addr));
+	orig_offset = pool_offset(addr);
+	offset = move_map(orig_offset);
+	if (offset != orig_offset) {
+		MDBG_MOVE("update ref %d %d -> %d\n",
+			  AO_LISP_IS_POOL(ref) ? MDBG_OFFSET(ref) : -1,
+			  orig_offset, offset);
+		*ref = ao_lisp_pool + offset;
+	}
+	if (busy(ao_lisp_busy, offset)) {
+		MDBG_MOVE("already moved\n");
+		return 1;
+	}
+	mark(ao_lisp_busy, offset);
+	MDBG_DO(ao_lisp_record(type, addr, ao_lisp_size(type, addr)));
+	return 0;
+}
+
+int
+ao_lisp_move(const struct ao_lisp_type *type, void **ref)
+{
+	int ret;
+	MDBG_MOVE("move object %d\n", MDBG_OFFSET(*ref));
+	MDBG_MOVE_IN();
+	ret = ao_lisp_move_memory(type, ref);
+	if (!ret) {
+		MDBG_MOVE("move recurse\n");
+		type->move(*ref);
+	}
+	MDBG_MOVE_OUT();
+	return ret;
+}
+
+int
+ao_lisp_poly_move(ao_poly *ref, uint8_t do_note_cons)
+{
+	uint8_t		type;
+	ao_poly		p = *ref;
+	int		ret;
+	void		*addr;
+	uint16_t	offset, orig_offset;
+	uint8_t		base_type;
+
+	base_type = type = ao_lisp_poly_base_type(p);
+
+	if (type == AO_LISP_INT)
+		return 1;
+
+	addr = ao_lisp_ref(p);
+	if (!AO_LISP_IS_POOL(addr))
+		return 1;
+
+	orig_offset = pool_offset(addr);
+	offset = move_map(orig_offset);
+
+	if (type == AO_LISP_CONS && do_note_cons) {
+		note_cons(orig_offset);
+		ret = 1;
+	} else {
+		if (type == AO_LISP_OTHER)
+			type = ao_lisp_other_type(ao_lisp_pool + offset);
+
+		const struct ao_lisp_type *lisp_type = ao_lisp_types[type];
+#if DBG_MEM
+		if (!lisp_type)
+			ao_lisp_abort();
+#endif
+
+		ret = ao_lisp_move(lisp_type, &addr);
+	}
+
+	/* Re-write the poly value */
+	if (offset != orig_offset) {
+		ao_poly np = ao_lisp_poly(ao_lisp_pool + offset, base_type);
+		MDBG_MOVE("poly %d moved %d -> %d\n",
+			  type, orig_offset, offset);
+		*ref = np;
+	}
+	return ret;
+}
+
+#if DBG_MEM
+void
+ao_lisp_validate(void)
+{
+	chunk_low = 0;
+	memset(ao_lisp_chunk, '\0', sizeof (ao_lisp_chunk));
+	walk(ao_lisp_mark_ref, ao_lisp_poly_mark_ref);
+}
+
+int dbg_allocs;
+
+#endif
+
+void *
+ao_lisp_alloc(int size)
+{
+	void	*addr;
+
+	MDBG_DO(++dbg_allocs);
+	MDBG_DO(if (dbg_validate) ao_lisp_validate());
+	size = ao_lisp_size_round(size);
+	if (AO_LISP_POOL - ao_lisp_top < size &&
+	    ao_lisp_collect(AO_LISP_COLLECT_INCREMENTAL) < size &&
+	    ao_lisp_collect(AO_LISP_COLLECT_FULL) < size)
+	{
+		ao_lisp_error(AO_LISP_OOM, "out of memory");
+		return NULL;
+	}
+	addr = ao_lisp_pool + ao_lisp_top;
+	ao_lisp_top += size;
+	return addr;
+}
+
+void
+ao_lisp_cons_stash(int id, struct ao_lisp_cons *cons)
+{
+	save_cons[id] = cons;
+}
+
+struct ao_lisp_cons *
+ao_lisp_cons_fetch(int id)
+{
+	struct ao_lisp_cons *cons = save_cons[id];
+	save_cons[id] = NULL;
+	return cons;
+}
+
+void
+ao_lisp_poly_stash(int id, ao_poly poly)
+{
+	save_poly[id] = poly;
+}
+
+ao_poly
+ao_lisp_poly_fetch(int id)
+{
+	ao_poly poly = save_poly[id];
+	save_poly[id] = AO_LISP_NIL;
+	return poly;
+}
+
+void
+ao_lisp_string_stash(int id, char *string)
+{
+	save_string[id] = string;
+}
+
+char *
+ao_lisp_string_fetch(int id)
+{
+	char *string = save_string[id];
+	save_string[id] = NULL;
+	return string;
+}
+
diff --git a/src/lisp/ao_lisp_os.h b/src/lisp/ao_lisp_os.h
new file mode 100644
index 00000000..5fa3686b
--- /dev/null
+++ b/src/lisp/ao_lisp_os.h
@@ -0,0 +1,53 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#ifndef _AO_LISP_OS_H_
+#define _AO_LISP_OS_H_
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <time.h>
+
+extern int ao_lisp_getc(void);
+
+static inline void
+ao_lisp_os_flush(void) {
+	fflush(stdout);
+}
+
+static inline void
+ao_lisp_abort(void)
+{
+	abort();
+}
+
+static inline void
+ao_lisp_os_led(int led)
+{
+	printf("leds set to 0x%x\n", led);
+}
+
+static inline void
+ao_lisp_os_delay(int delay)
+{
+	struct timespec ts = {
+		.tv_sec = delay / 1000,
+		.tv_nsec = (delay % 1000) * 1000000,
+	};
+	nanosleep(&ts, NULL);
+}
+#endif
diff --git a/src/lisp/ao_lisp_poly.c b/src/lisp/ao_lisp_poly.c
new file mode 100644
index 00000000..fb3b06fe
--- /dev/null
+++ b/src/lisp/ao_lisp_poly.c
@@ -0,0 +1,102 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
+struct ao_lisp_funcs {
+	void (*print)(ao_poly);
+	void (*patom)(ao_poly);
+};
+
+static const struct ao_lisp_funcs ao_lisp_funcs[AO_LISP_NUM_TYPE] = {
+	[AO_LISP_CONS] = {
+		.print = ao_lisp_cons_print,
+		.patom = ao_lisp_cons_patom,
+	},
+	[AO_LISP_STRING] = {
+		.print = ao_lisp_string_print,
+		.patom = ao_lisp_string_patom,
+	},
+	[AO_LISP_INT] = {
+		.print = ao_lisp_int_print,
+		.patom = ao_lisp_int_print,
+	},
+	[AO_LISP_ATOM] = {
+		.print = ao_lisp_atom_print,
+		.patom = ao_lisp_atom_print,
+	},
+	[AO_LISP_BUILTIN] = {
+		.print = ao_lisp_builtin_print,
+		.patom = ao_lisp_builtin_print,
+	},
+	[AO_LISP_FRAME] = {
+		.print = ao_lisp_frame_print,
+		.patom = ao_lisp_frame_print,
+	},
+	[AO_LISP_LAMBDA] = {
+		.print = ao_lisp_lambda_print,
+		.patom = ao_lisp_lambda_print,
+	},
+	[AO_LISP_STACK] = {
+		.print = ao_lisp_stack_print,
+		.patom = ao_lisp_stack_print,
+	},
+};
+
+static const struct ao_lisp_funcs *
+funcs(ao_poly p)
+{
+	uint8_t	type = ao_lisp_poly_type(p);
+
+	if (type < AO_LISP_NUM_TYPE)
+		return &ao_lisp_funcs[type];
+	return NULL;
+}
+
+void
+ao_lisp_poly_print(ao_poly p)
+{
+	const struct ao_lisp_funcs *f = funcs(p);
+
+	if (f && f->print)
+		f->print(p);
+}
+
+void
+ao_lisp_poly_patom(ao_poly p)
+{
+	const struct ao_lisp_funcs *f = funcs(p);
+
+	if (f && f->patom)
+		f->patom(p);
+}
+
+void *
+ao_lisp_ref(ao_poly poly) {
+	if (poly == AO_LISP_NIL)
+		return NULL;
+	if (poly & AO_LISP_CONST)
+		return (void *) (ao_lisp_const + (poly & AO_LISP_REF_MASK) - 4);
+	return (void *) (ao_lisp_pool + (poly & AO_LISP_REF_MASK) - 4);
+}
+
+ao_poly
+ao_lisp_poly(const void *addr, ao_poly type) {
+	const uint8_t	*a = addr;
+	if (a == NULL)
+		return AO_LISP_NIL;
+	if (AO_LISP_IS_CONST(a))
+		return AO_LISP_CONST | (a - ao_lisp_const + 4) | type;
+	return (a - ao_lisp_pool + 4) | type;
+}
diff --git a/src/lisp/ao_lisp_read.c b/src/lisp/ao_lisp_read.c
new file mode 100644
index 00000000..84ef2a61
--- /dev/null
+++ b/src/lisp/ao_lisp_read.c
@@ -0,0 +1,498 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+#include "ao_lisp_read.h"
+
+static const uint16_t	lex_classes[128] = {
+	IGNORE,		/* ^@ */
+	IGNORE,		/* ^A */
+	IGNORE,		/* ^B */
+	IGNORE,		/* ^C */
+	IGNORE,		/* ^D */
+	IGNORE,		/* ^E */
+	IGNORE,		/* ^F */
+	IGNORE,		/* ^G */
+	IGNORE,		/* ^H */
+	WHITE,		/* ^I */
+	WHITE,		/* ^J */
+	WHITE,		/* ^K */
+	WHITE,		/* ^L */
+	WHITE,		/* ^M */
+	IGNORE,		/* ^N */
+	IGNORE,		/* ^O */
+	IGNORE,		/* ^P */
+	IGNORE,		/* ^Q */
+	IGNORE,		/* ^R */
+	IGNORE,		/* ^S */
+	IGNORE,		/* ^T */
+	IGNORE,		/* ^U */
+	IGNORE,		/* ^V */
+	IGNORE,		/* ^W */
+	IGNORE,		/* ^X */
+	IGNORE,		/* ^Y */
+	IGNORE,		/* ^Z */
+	IGNORE,		/* ^[ */
+	IGNORE,		/* ^\ */
+	IGNORE,		/* ^] */
+	IGNORE,		/* ^^ */
+	IGNORE,		/* ^_ */
+	PRINTABLE|WHITE,	/*    */
+ 	PRINTABLE,		/* ! */
+ 	PRINTABLE|STRINGC,	/* " */
+ 	PRINTABLE|COMMENT,	/* # */
+ 	PRINTABLE,		/* $ */
+ 	PRINTABLE,		/* % */
+ 	PRINTABLE,		/* & */
+ 	PRINTABLE|QUOTEC,	/* ' */
+ 	PRINTABLE|BRA,		/* ( */
+ 	PRINTABLE|KET,		/* ) */
+ 	PRINTABLE,		/* * */
+ 	PRINTABLE|SIGN,		/* + */
+ 	PRINTABLE,		/* , */
+ 	PRINTABLE|SIGN,		/* - */
+ 	PRINTABLE,		/* . */
+ 	PRINTABLE,		/* / */
+ 	PRINTABLE|DIGIT,	/* 0 */
+ 	PRINTABLE|DIGIT,	/* 1 */
+ 	PRINTABLE|DIGIT,	/* 2 */
+ 	PRINTABLE|DIGIT,	/* 3 */
+ 	PRINTABLE|DIGIT,	/* 4 */
+ 	PRINTABLE|DIGIT,	/* 5 */
+ 	PRINTABLE|DIGIT,	/* 6 */
+ 	PRINTABLE|DIGIT,	/* 7 */
+ 	PRINTABLE|DIGIT,	/* 8 */
+ 	PRINTABLE|DIGIT,	/* 9 */
+ 	PRINTABLE,		/* : */
+ 	PRINTABLE|COMMENT,	/* ; */
+ 	PRINTABLE,		/* < */
+ 	PRINTABLE,		/* = */
+ 	PRINTABLE,		/* > */
+ 	PRINTABLE,		/* ? */
+  	PRINTABLE,		/*  @ */
+	PRINTABLE,		/*  A */
+	PRINTABLE,		/*  B */
+	PRINTABLE,		/*  C */
+	PRINTABLE,		/*  D */
+	PRINTABLE,		/*  E */
+	PRINTABLE,		/*  F */
+	PRINTABLE,		/*  G */
+	PRINTABLE,		/*  H */
+	PRINTABLE,		/*  I */
+	PRINTABLE,		/*  J */
+	PRINTABLE,		/*  K */
+	PRINTABLE,		/*  L */
+	PRINTABLE,		/*  M */
+	PRINTABLE,		/*  N */
+	PRINTABLE,		/*  O */
+	PRINTABLE,		/*  P */
+	PRINTABLE,		/*  Q */
+	PRINTABLE,		/*  R */
+	PRINTABLE,		/*  S */
+	PRINTABLE,		/*  T */
+	PRINTABLE,		/*  U */
+	PRINTABLE,		/*  V */
+	PRINTABLE,		/*  W */
+	PRINTABLE,		/*  X */
+	PRINTABLE,		/*  Y */
+	PRINTABLE,		/*  Z */
+	PRINTABLE,		/*  [ */
+	PRINTABLE|BACKSLASH,	/*  \ */
+	PRINTABLE,		/*  ] */
+	PRINTABLE,		/*  ^ */
+	PRINTABLE,		/*  _ */
+  	PRINTABLE,		/*  ` */
+	PRINTABLE,		/*  a */
+	PRINTABLE,		/*  b */
+	PRINTABLE,		/*  c */
+	PRINTABLE,		/*  d */
+	PRINTABLE,		/*  e */
+	PRINTABLE,		/*  f */
+	PRINTABLE,		/*  g */
+	PRINTABLE,		/*  h */
+	PRINTABLE,		/*  i */
+	PRINTABLE,		/*  j */
+	PRINTABLE,		/*  k */
+	PRINTABLE,		/*  l */
+	PRINTABLE,		/*  m */
+	PRINTABLE,		/*  n */
+	PRINTABLE,		/*  o */
+	PRINTABLE,		/*  p */
+	PRINTABLE,		/*  q */
+	PRINTABLE,		/*  r */
+	PRINTABLE,		/*  s */
+	PRINTABLE,		/*  t */
+	PRINTABLE,		/*  u */
+	PRINTABLE,		/*  v */
+	PRINTABLE,		/*  w */
+	PRINTABLE,		/*  x */
+	PRINTABLE,		/*  y */
+	PRINTABLE,		/*  z */
+	PRINTABLE,		/*  { */
+	PRINTABLE|VBAR,		/*  | */
+	PRINTABLE,		/*  } */
+	PRINTABLE|TWIDDLE,	/*  ~ */
+	IGNORE,			/*  ^? */
+};
+
+static int lex_unget_c;
+
+static inline int
+lex_get()
+{
+	int	c;
+	if (lex_unget_c) {
+		c = lex_unget_c;
+		lex_unget_c = 0;
+	} else {
+		c = ao_lisp_getc();
+	}
+	return c;
+}
+
+static inline void
+lex_unget(int c)
+{
+	if (c != EOF)
+		lex_unget_c = c;
+}
+
+static int
+lex_quoted (void)
+{
+	int	c;
+	int	v;
+	int	count;
+
+	c = lex_get();
+	if (c == EOF)
+		return EOF;
+	c &= 0x7f;
+ 	switch (c) {
+	case 'n':
+		return '\n';
+	case 'f':
+		return '\f';
+	case 'b':
+		return '\b';
+	case 'r':
+		return '\r';
+	case 'v':
+		return '\v';
+	case 't':
+		return '\t';
+	case '0':
+	case '1':
+	case '2':
+	case '3':
+	case '4':
+	case '5':
+	case '6':
+	case '7':
+		v = c - '0';
+		count = 1;
+		while (count <= 3) {
+			c = lex_get();
+			if (c == EOF)
+				return EOF;
+			c &= 0x7f;
+			if (c < '0' || '7' < c) {
+				lex_unget(c);
+				break;
+			}
+			v = (v << 3) + c - '0';
+			++count;
+		}
+		return v;
+	default:
+		return c;
+	}
+}
+
+static uint16_t	lex_class;
+
+static int
+lexc(void)
+{
+	int	c;
+	do {
+		c = lex_get();
+		if (c == EOF) {
+			lex_class = ENDOFFILE;
+			c = 0;
+		} else {
+			c &= 0x7f;
+			lex_class = lex_classes[c];
+			if (lex_class & BACKSLASH) {
+				c = lex_quoted();
+				if (c == EOF)
+					lex_class = ENDOFFILE;
+				else
+					lex_class = PRINTABLE;
+			}
+		}
+	} while (lex_class & IGNORE);
+	return c;
+}
+
+#define AO_LISP_TOKEN_MAX	32
+
+static char	token_string[AO_LISP_TOKEN_MAX];
+static int	token_int;
+static int	token_len;
+
+static inline void add_token(int c) {
+	if (c && token_len < AO_LISP_TOKEN_MAX - 1)
+		token_string[token_len++] = c;
+}
+
+static inline void end_token(void) {
+	token_string[token_len] = '\0';
+}
+
+static int
+lex(void)
+{
+	int	c;
+
+	token_len = 0;
+	for (;;) {
+		c = lexc();
+		if (lex_class & ENDOFFILE)
+			return END;
+
+		if (lex_class & WHITE)
+			continue;
+
+		if (lex_class & COMMENT) {
+			while ((c = lexc()) != '\n') {
+				if (lex_class & ENDOFFILE)
+					return END;
+			}
+			continue;
+		}
+
+		if (lex_class & (BRA|KET|QUOTEC)) {
+			add_token(c);
+			end_token();
+			switch (c) {
+			case '(':
+				return OPEN;
+			case ')':
+				return CLOSE;
+			case '\'':
+				return QUOTE;
+			}
+		}
+		if (lex_class & TWIDDLE) {
+			token_int = lexc();
+			return NUM;
+		}
+		if (lex_class & STRINGC) {
+			for (;;) {
+				c = lexc();
+				if (lex_class & (STRINGC|ENDOFFILE)) {
+					end_token();
+					return STRING;
+				}
+				add_token(c);
+			}
+		}
+		if (lex_class & PRINTABLE) {
+			int	isnum;
+			int	hasdigit;
+			int	isneg;
+
+			isnum = 1;
+			hasdigit = 0;
+			token_int = 0;
+			isneg = 0;
+			for (;;) {
+				if (!(lex_class & NUMBER)) {
+					isnum = 0;
+				} else {
+ 					if (token_len != 0 &&
+					    (lex_class & SIGN))
+					{
+						isnum = 0;
+					}
+					if (c == '-')
+						isneg = 1;
+					if (lex_class & DIGIT) {
+						hasdigit = 1;
+						if (isnum)
+							token_int = token_int * 10 + c - '0';
+					}
+				}
+				add_token (c);
+				c = lexc ();
+				if (lex_class & (NOTNAME)) {
+//					if (lex_class & ENDOFFILE)
+//						clearerr (f);
+					lex_unget(c);
+					end_token ();
+					if (isnum && hasdigit) {
+						if (isneg)
+							token_int = -token_int;
+						return NUM;
+					}
+					return NAME;
+				}
+			}
+
+		}
+	}
+}
+
+static int parse_token;
+
+struct ao_lisp_cons	*ao_lisp_read_cons;
+struct ao_lisp_cons	*ao_lisp_read_cons_tail;
+struct ao_lisp_cons	*ao_lisp_read_stack;
+
+static int
+push_read_stack(int cons, int in_quote)
+{
+	DBGI("push read stack %p %d\n", ao_lisp_read_cons, in_quote);
+	DBG_IN();
+	if (cons) {
+		ao_lisp_read_stack = ao_lisp_cons_cons(ao_lisp_cons_poly(ao_lisp_read_cons),
+					       ao_lisp_cons_cons(ao_lisp_int_poly(in_quote),
+								 ao_lisp_read_stack));
+		if (!ao_lisp_read_stack)
+			return 0;
+	}
+	ao_lisp_read_cons = NULL;
+	ao_lisp_read_cons_tail = NULL;
+	return 1;
+}
+
+static int
+pop_read_stack(int cons)
+{
+	int	in_quote = 0;
+	if (cons) {
+		ao_lisp_read_cons = ao_lisp_poly_cons(ao_lisp_read_stack->car);
+		ao_lisp_read_stack = ao_lisp_poly_cons(ao_lisp_read_stack->cdr);
+		in_quote = ao_lisp_poly_int(ao_lisp_read_stack->car);
+		ao_lisp_read_stack = ao_lisp_poly_cons(ao_lisp_read_stack->cdr);
+		for (ao_lisp_read_cons_tail = ao_lisp_read_cons;
+		     ao_lisp_read_cons_tail && ao_lisp_read_cons_tail->cdr;
+		     ao_lisp_read_cons_tail = ao_lisp_poly_cons(ao_lisp_read_cons_tail->cdr))
+			;
+	} else {
+		ao_lisp_read_cons = 0;
+		ao_lisp_read_cons_tail = 0;
+		ao_lisp_read_stack = 0;
+	}
+	DBG_OUT();
+	DBGI("pop read stack %p %d\n", ao_lisp_read_cons, in_quote);
+	return in_quote;
+}
+
+ao_poly
+ao_lisp_read(void)
+{
+	struct ao_lisp_atom	*atom;
+	char			*string;
+	int			cons;
+	int			in_quote;
+	ao_poly			v;
+
+	parse_token = lex();
+	DBGI("token %d (%s)\n", parse_token, token_string);
+
+	cons = 0;
+	in_quote = 0;
+	ao_lisp_read_cons = ao_lisp_read_cons_tail = ao_lisp_read_stack = 0;
+	for (;;) {
+		while (parse_token == OPEN) {
+			if (!push_read_stack(cons, in_quote))
+				return AO_LISP_NIL;
+			cons++;
+			in_quote = 0;
+			parse_token = lex();
+			DBGI("token %d (%s)\n", parse_token, token_string);
+		}
+
+		switch (parse_token) {
+		case END:
+		default:
+			if (cons)
+				ao_lisp_error(AO_LISP_EOF, "unexpected end of file");
+			return _ao_lisp_atom_eof;
+			break;
+		case NAME:
+			atom = ao_lisp_atom_intern(token_string);
+			if (atom)
+				v = ao_lisp_atom_poly(atom);
+			else
+				v = AO_LISP_NIL;
+			break;
+		case NUM:
+			v = ao_lisp_int_poly(token_int);
+			break;
+		case STRING:
+			string = ao_lisp_string_copy(token_string);
+			if (string)
+				v = ao_lisp_string_poly(string);
+			else
+				v = AO_LISP_NIL;
+			break;
+		case QUOTE:
+			if (!push_read_stack(cons, in_quote))
+				return AO_LISP_NIL;
+			cons++;
+			in_quote = 1;
+			v = _ao_lisp_atom_quote;
+			break;
+		case CLOSE:
+			if (!cons) {
+				v = AO_LISP_NIL;
+				break;
+			}
+			v = ao_lisp_cons_poly(ao_lisp_read_cons);
+			--cons;
+			in_quote = pop_read_stack(cons);
+			break;
+		}
+
+		/* loop over QUOTE ends */
+		for (;;) {
+			if (!cons)
+				return v;
+
+			struct ao_lisp_cons	*read = ao_lisp_cons_cons(v, NULL);
+			if (!read)
+				return AO_LISP_NIL;
+
+			if (ao_lisp_read_cons_tail)
+				ao_lisp_read_cons_tail->cdr = ao_lisp_cons_poly(read);
+			else
+				ao_lisp_read_cons = read;
+			ao_lisp_read_cons_tail = read;
+
+			if (!in_quote || !ao_lisp_read_cons->cdr)
+				break;
+
+			v = ao_lisp_cons_poly(ao_lisp_read_cons);
+			--cons;
+			in_quote = pop_read_stack(cons);
+		}
+
+		parse_token = lex();
+		DBGI("token %d (%s)\n", parse_token, token_string);
+	}
+	return v;
+}
diff --git a/src/lisp/ao_lisp_read.h b/src/lisp/ao_lisp_read.h
new file mode 100644
index 00000000..1c994d56
--- /dev/null
+++ b/src/lisp/ao_lisp_read.h
@@ -0,0 +1,49 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#ifndef _AO_LISP_READ_H_
+#define _AO_LISP_READ_H_
+
+# define END	0
+# define NAME	1
+# define OPEN  	2
+# define CLOSE	3
+# define QUOTE	4
+# define STRING	5
+# define NUM	6
+
+/*
+ * character classes
+ */
+
+# define PRINTABLE	0x00000001	/* \t \n ' ' - '~' */
+# define QUOTED		0x00000002	/* \ anything */
+# define BRA		0x00000004	/* ( [ { */
+# define KET		0x00000008	/* ) ] } */
+# define WHITE		0x00000010	/* ' ' \t \n */
+# define DIGIT		0x00000020	/* [0-9] */
+# define SIGN		0x00000040	/* +- */
+# define ENDOFFILE	0x00000080	/* end of file */
+# define COMMENT	0x00000100	/* ; # */
+# define IGNORE		0x00000200	/* \0 - ' ' */
+# define QUOTEC		0x00000400	/* ' */
+# define BACKSLASH	0x00000800	/* \ */
+# define VBAR		0x00001000	/* | */
+# define TWIDDLE	0x00002000	/* ~ */
+# define STRINGC	0x00004000	/* " */
+
+# define NOTNAME	(STRINGC|TWIDDLE|VBAR|QUOTEC|COMMENT|ENDOFFILE|WHITE|KET|BRA)
+# define NUMBER		(DIGIT|SIGN)
+
+#endif /* _AO_LISP_READ_H_ */
diff --git a/src/lisp/ao_lisp_rep.c b/src/lisp/ao_lisp_rep.c
new file mode 100644
index 00000000..3be95d44
--- /dev/null
+++ b/src/lisp/ao_lisp_rep.c
@@ -0,0 +1,34 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
+ao_poly
+ao_lisp_read_eval_print(void)
+{
+	ao_poly	in, out = AO_LISP_NIL;
+	for(;;) {
+		in = ao_lisp_read();
+		if (in == _ao_lisp_atom_eof || in == AO_LISP_NIL)
+			break;
+		out = ao_lisp_eval(in);
+		if (ao_lisp_exception) {
+			ao_lisp_exception = 0;
+		} else {
+			ao_lisp_poly_print(out);
+			putchar ('\n');
+		}
+	}
+	return out;
+}
diff --git a/src/lisp/ao_lisp_save.c b/src/lisp/ao_lisp_save.c
new file mode 100644
index 00000000..4f850fb9
--- /dev/null
+++ b/src/lisp/ao_lisp_save.c
@@ -0,0 +1,76 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <ao_lisp.h>
+
+ao_poly
+ao_lisp_save(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_save, cons, 0, 0))
+		return AO_LISP_NIL;
+
+#ifdef AO_LISP_SAVE
+	struct ao_lisp_os_save *os = (struct ao_lisp_os_save *) (void *) &ao_lisp_pool[AO_LISP_POOL];
+
+	ao_lisp_collect(AO_LISP_COLLECT_FULL);
+	os->atoms = ao_lisp_atom_poly(ao_lisp_atoms);
+	os->globals = ao_lisp_frame_poly(ao_lisp_frame_global);
+	os->const_checksum = ao_lisp_const_checksum;
+	os->const_checksum_inv = (uint16_t) ~ao_lisp_const_checksum;
+
+	if (ao_lisp_os_save())
+		return _ao_lisp_atom_t;
+#endif
+	return AO_LISP_NIL;
+}
+
+ao_poly
+ao_lisp_restore(struct ao_lisp_cons *cons)
+{
+	if (!ao_lisp_check_argc(_ao_lisp_atom_save, cons, 0, 0))
+		return AO_LISP_NIL;
+
+#ifdef AO_LISP_SAVE
+	struct ao_lisp_os_save save;
+	struct ao_lisp_os_save *os = (struct ao_lisp_os_save *) (void *) &ao_lisp_pool[AO_LISP_POOL];
+
+	if (!ao_lisp_os_restore_save(&save, AO_LISP_POOL))
+		return ao_lisp_error(AO_LISP_INVALID, "header restore failed");
+
+	if (save.const_checksum != ao_lisp_const_checksum ||
+	    save.const_checksum_inv != (uint16_t) ~ao_lisp_const_checksum)
+	{
+		return ao_lisp_error(AO_LISP_INVALID, "image is corrupted or stale");
+	}
+
+	if (ao_lisp_os_restore()) {
+
+		ao_lisp_atoms = ao_lisp_poly_atom(os->atoms);
+		ao_lisp_frame_global = ao_lisp_poly_frame(os->globals);
+
+		/* Clear the eval global variabls */
+		ao_lisp_eval_clear_globals();
+
+		/* Reset the allocator */
+		ao_lisp_top = AO_LISP_POOL;
+		ao_lisp_collect(AO_LISP_COLLECT_FULL);
+
+		/* Re-create the evaluator stack */
+		if (!ao_lisp_eval_restart())
+			return AO_LISP_NIL;
+		return _ao_lisp_atom_t;
+	}
+#endif
+	return AO_LISP_NIL;
+}
diff --git a/src/lisp/ao_lisp_stack.c b/src/lisp/ao_lisp_stack.c
new file mode 100644
index 00000000..53adf432
--- /dev/null
+++ b/src/lisp/ao_lisp_stack.c
@@ -0,0 +1,278 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include "ao_lisp.h"
+
+const struct ao_lisp_type ao_lisp_stack_type;
+
+static int
+stack_size(void *addr)
+{
+	(void) addr;
+	return sizeof (struct ao_lisp_stack);
+}
+
+static void
+stack_mark(void *addr)
+{
+	struct ao_lisp_stack	*stack = addr;
+	for (;;) {
+		ao_lisp_poly_mark(stack->sexprs, 0);
+		ao_lisp_poly_mark(stack->values, 0);
+		/* no need to mark values_tail */
+		ao_lisp_poly_mark(stack->frame, 0);
+		ao_lisp_poly_mark(stack->list, 0);
+		stack = ao_lisp_poly_stack(stack->prev);
+		if (ao_lisp_mark_memory(&ao_lisp_stack_type, stack))
+			break;
+	}
+}
+
+static void
+stack_move(void *addr)
+{
+	struct ao_lisp_stack	*stack = addr;
+
+	while (stack) {
+		struct ao_lisp_stack	*prev;
+		int			ret;
+		(void) ao_lisp_poly_move(&stack->sexprs, 0);
+		(void) ao_lisp_poly_move(&stack->values, 0);
+		(void) ao_lisp_poly_move(&stack->values_tail, 0);
+		(void) ao_lisp_poly_move(&stack->frame, 0);
+		(void) ao_lisp_poly_move(&stack->list, 0);
+		prev = ao_lisp_poly_stack(stack->prev);
+		if (!prev)
+			break;
+		ret = ao_lisp_move_memory(&ao_lisp_stack_type, (void **) &prev);
+		if (prev != ao_lisp_poly_stack(stack->prev))
+			stack->prev = ao_lisp_stack_poly(prev);
+		if (ret)
+			break;
+		stack = prev;
+	}
+}
+
+const struct ao_lisp_type ao_lisp_stack_type = {
+	.size = stack_size,
+	.mark = stack_mark,
+	.move = stack_move,
+	.name = "stack"
+};
+
+struct ao_lisp_stack		*ao_lisp_stack_free_list;
+
+void
+ao_lisp_stack_reset(struct ao_lisp_stack *stack)
+{
+	stack->state = eval_sexpr;
+	stack->sexprs = AO_LISP_NIL;
+	stack->values = AO_LISP_NIL;
+	stack->values_tail = AO_LISP_NIL;
+}
+
+static struct ao_lisp_stack *
+ao_lisp_stack_new(void)
+{
+	struct ao_lisp_stack *stack;
+
+	if (ao_lisp_stack_free_list) {
+		stack = ao_lisp_stack_free_list;
+		ao_lisp_stack_free_list = ao_lisp_poly_stack(stack->prev);
+	} else {
+		stack = ao_lisp_alloc(sizeof (struct ao_lisp_stack));
+		if (!stack)
+			return 0;
+		stack->type = AO_LISP_STACK;
+	}
+	ao_lisp_stack_reset(stack);
+	return stack;
+}
+
+int
+ao_lisp_stack_push(void)
+{
+	struct ao_lisp_stack	*stack = ao_lisp_stack_new();
+
+	if (!stack)
+		return 0;
+
+	stack->prev = ao_lisp_stack_poly(ao_lisp_stack);
+	stack->frame = ao_lisp_frame_poly(ao_lisp_frame_current);
+	stack->list = AO_LISP_NIL;
+
+	ao_lisp_stack = stack;
+
+	DBGI("stack push\n");
+	DBG_FRAMES();
+	DBG_IN();
+	return 1;
+}
+
+void
+ao_lisp_stack_pop(void)
+{
+	ao_poly			prev;
+	struct ao_lisp_frame	*prev_frame;
+
+	if (!ao_lisp_stack)
+		return;
+	prev = ao_lisp_stack->prev;
+	if (!ao_lisp_stack_marked(ao_lisp_stack)) {
+		ao_lisp_stack->prev = ao_lisp_stack_poly(ao_lisp_stack_free_list);
+		ao_lisp_stack_free_list = ao_lisp_stack;
+	}
+
+	ao_lisp_stack = ao_lisp_poly_stack(prev);
+	prev_frame = ao_lisp_frame_current;
+	if (ao_lisp_stack)
+		ao_lisp_frame_current = ao_lisp_poly_frame(ao_lisp_stack->frame);
+	else
+		ao_lisp_frame_current = NULL;
+	if (ao_lisp_frame_current != prev_frame)
+		ao_lisp_frame_free(prev_frame);
+	DBG_OUT();
+	DBGI("stack pop\n");
+	DBG_FRAMES();
+}
+
+void
+ao_lisp_stack_clear(void)
+{
+	ao_lisp_stack = NULL;
+	ao_lisp_frame_current = NULL;
+	ao_lisp_v = AO_LISP_NIL;
+}
+
+void
+ao_lisp_stack_print(ao_poly poly)
+{
+	struct ao_lisp_stack *s = ao_lisp_poly_stack(poly);
+
+	while (s) {
+		if (s->type & AO_LISP_STACK_PRINT) {
+			printf("[recurse...]");
+			return;
+		}
+		s->type |= AO_LISP_STACK_PRINT;
+		printf("\t[\n");
+		printf("\t\texpr:   "); ao_lisp_poly_print(s->list); printf("\n");
+		printf("\t\tstate:  %s\n", ao_lisp_state_names[s->state]);
+		ao_lisp_error_poly ("values: ", s->values, s->values_tail);
+		ao_lisp_error_poly ("sexprs: ", s->sexprs, AO_LISP_NIL);
+		ao_lisp_error_frame(2, "frame:  ", ao_lisp_poly_frame(s->frame));
+		printf("\t]\n");
+		s->type &= ~AO_LISP_STACK_PRINT;
+		s = ao_lisp_poly_stack(s->prev);
+	}
+}
+
+/*
+ * Copy a stack, being careful to keep everybody referenced
+ */
+static struct ao_lisp_stack *
+ao_lisp_stack_copy(struct ao_lisp_stack *old)
+{
+	struct ao_lisp_stack *new = NULL;
+	struct ao_lisp_stack *n, *prev = NULL;
+
+	while (old) {
+		ao_lisp_stack_stash(0, old);
+		ao_lisp_stack_stash(1, new);
+		ao_lisp_stack_stash(2, prev);
+		n = ao_lisp_stack_new();
+		prev = ao_lisp_stack_fetch(2);
+		new = ao_lisp_stack_fetch(1);
+		old = ao_lisp_stack_fetch(0);
+		if (!n)
+			return NULL;
+
+		ao_lisp_stack_mark(old);
+		ao_lisp_frame_mark(ao_lisp_poly_frame(old->frame));
+		*n = *old;
+
+		if (prev)
+			prev->prev = ao_lisp_stack_poly(n);
+		else
+			new = n;
+		prev = n;
+
+		old = ao_lisp_poly_stack(old->prev);
+	}
+	return new;
+}
+
+/*
+ * Evaluate a continuation invocation
+ */
+ao_poly
+ao_lisp_stack_eval(void)
+{
+	struct ao_lisp_stack	*new = ao_lisp_stack_copy(ao_lisp_poly_stack(ao_lisp_v));
+	if (!new)
+		return AO_LISP_NIL;
+
+	struct ao_lisp_cons	*cons = ao_lisp_poly_cons(ao_lisp_stack->values);
+
+	if (!cons || !cons->cdr)
+		return ao_lisp_error(AO_LISP_INVALID, "continuation requires a value");
+
+	new->state = eval_val;
+
+	ao_lisp_stack = new;
+	ao_lisp_frame_current = ao_lisp_poly_frame(ao_lisp_stack->frame);
+
+	return ao_lisp_poly_cons(cons->cdr)->car;
+}
+
+/*
+ * Call with current continuation. This calls a lambda, passing
+ * it a single argument which is the current continuation
+ */
+ao_poly
+ao_lisp_call_cc(struct ao_lisp_cons *cons)
+{
+	struct ao_lisp_stack	*new;
+	ao_poly			v;
+
+	/* Make sure the single parameter is a lambda */
+	if (!ao_lisp_check_argc(_ao_lisp_atom_call2fcc, cons, 1, 1))
+		return AO_LISP_NIL;
+	if (!ao_lisp_check_argt(_ao_lisp_atom_call2fcc, cons, 0, AO_LISP_LAMBDA, 0))
+		return AO_LISP_NIL;
+
+	/* go get the lambda */
+	ao_lisp_v = ao_lisp_arg(cons, 0);
+
+	/* Note that the whole call chain now has
+	 * a reference to it which may escape
+	 */
+	new = ao_lisp_stack_copy(ao_lisp_stack);
+	if (!new)
+		return AO_LISP_NIL;
+
+	/* re-fetch cons after the allocation */
+	cons = ao_lisp_poly_cons(ao_lisp_poly_cons(ao_lisp_stack->values)->cdr);
+
+	/* Reset the arg list to the current stack,
+	 * and call the lambda
+	 */
+
+	cons->car = ao_lisp_stack_poly(new);
+	cons->cdr = AO_LISP_NIL;
+	v = ao_lisp_lambda_eval();
+	ao_lisp_stack->sexprs = v;
+	ao_lisp_stack->state = eval_progn;
+	return AO_LISP_NIL;
+}
diff --git a/src/lisp/ao_lisp_string.c b/src/lisp/ao_lisp_string.c
new file mode 100644
index 00000000..cd7b27a9
--- /dev/null
+++ b/src/lisp/ao_lisp_string.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright © 2016 Keith Packard <keithp@keithp.com>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
+ */
+
+#include "ao_lisp.h"
+
+static void string_mark(void *addr)
+{
+	(void) addr;
+}
+
+static int string_size(void *addr)
+{
+	if (!addr)
+		return 0;
+	return strlen(addr) + 1;
+}
+
+static void string_move(void *addr)
+{
+	(void) addr;
+}
+
+const struct ao_lisp_type ao_lisp_string_type = {
+	.mark = string_mark,
+	.size = string_size,
+	.move = string_move,
+	.name = "string",
+};
+
+char *
+ao_lisp_string_copy(char *a)
+{
+	int	alen = strlen(a);
+
+	ao_lisp_string_stash(0, a);
+	char	*r = ao_lisp_alloc(alen + 1);
+	a = ao_lisp_string_fetch(0);
+	if (!r)
+		return NULL;
+	strcpy(r, a);
+	return r;
+}
+
+char *
+ao_lisp_string_cat(char *a, char *b)
+{
+	int	alen = strlen(a);
+	int	blen = strlen(b);
+
+	ao_lisp_string_stash(0, a);
+	ao_lisp_string_stash(1, b);
+	char	*r = ao_lisp_alloc(alen + blen + 1);
+	a = ao_lisp_string_fetch(0);
+	b = ao_lisp_string_fetch(1);
+	if (!r)
+		return NULL;
+	strcpy(r, a);
+	strcpy(r+alen, b);
+	return r;
+}
+
+ao_poly
+ao_lisp_string_pack(struct ao_lisp_cons *cons)
+{
+	int	len = ao_lisp_cons_length(cons);
+	ao_lisp_cons_stash(0, cons);
+	char	*r = ao_lisp_alloc(len + 1);
+	cons = ao_lisp_cons_fetch(0);
+	char	*s = r;
+
+	while (cons) {
+		if (ao_lisp_poly_type(cons->car) != AO_LISP_INT)
+			return ao_lisp_error(AO_LISP_INVALID, "non-int passed to pack");
+		*s++ = ao_lisp_poly_int(cons->car);
+		cons = ao_lisp_poly_cons(cons->cdr);
+	}
+	*s++ = 0;
+	return ao_lisp_string_poly(r);
+}
+
+ao_poly
+ao_lisp_string_unpack(char *a)
+{
+	struct ao_lisp_cons	*cons = NULL, *tail = NULL;
+	int			c;
+	int			i;
+
+	for (i = 0; (c = a[i]); i++) {
+		ao_lisp_cons_stash(0, cons);
+		ao_lisp_cons_stash(1, tail);
+		ao_lisp_string_stash(0, a);
+		struct ao_lisp_cons	*n = ao_lisp_cons_cons(ao_lisp_int_poly(c), NULL);
+		a = ao_lisp_string_fetch(0);
+		cons = ao_lisp_cons_fetch(0);
+		tail = ao_lisp_cons_fetch(1);
+
+		if (!n) {
+			cons = NULL;
+			break;
+		}
+		if (tail)
+			tail->cdr = ao_lisp_cons_poly(n);
+		else
+			cons = n;
+		tail = n;
+	}
+	return ao_lisp_cons_poly(cons);
+}
+
+void
+ao_lisp_string_print(ao_poly p)
+{
+	char	*s = ao_lisp_poly_string(p);
+	char	c;
+
+	putchar('"');
+	while ((c = *s++)) {
+		switch (c) {
+		case '\n':
+			printf ("\\n");
+			break;
+		case '\r':
+			printf ("\\r");
+			break;
+		case '\t':
+			printf ("\\t");
+			break;
+		default:
+			putchar(c);
+			break;
+		}
+	}
+	putchar('"');
+}
+
+void
+ao_lisp_string_patom(ao_poly p)
+{
+	char	*s = ao_lisp_poly_string(p);
+	char	c;
+
+	while ((c = *s++))
+		putchar(c);
+}