altos/lisp: Add save/restore infrastructure. Needs OS support to work.

This sticks a few globals past the end of the heap and then asks the
OS to save the heap. On restore, the heap is re-populated by the OS
and then various global variables reset.

Signed-off-by: Keith Packard <keithp@keithp.com>

1 files changed, 57 insertions, 0 deletions

diff --git a/src/lisp/ao_lisp_save.c b/src/lisp/ao_lisp_save.c
new file mode 100644
index 00000000..2b19fdcb
--- /dev/null
+++ b/src/lisp/ao_lisp_save.c
@@ -0,0 +1,57 @@
+/*
+ * 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)
+{
+#ifdef AO_LISP_SAVE
+	struct ao_lisp_os_save *os = (struct ao_lisp_os_save *) &ao_lisp_pool[AO_LISP_POOL];
+
+	ao_lisp_collect();
+	os->ao_lisp_atoms = ao_lisp_atom_poly(ao_lisp_atoms);
+	os->ao_lisp_globals = ao_lisp_frame_poly(ao_lisp_frame_global);
+	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)
+{
+#ifdef AO_LISP_SAVE
+	struct ao_lisp_os_save *os = (struct ao_lisp_os_save *) &ao_lisp_pool[AO_LISP_POOL];
+
+	if (ao_lisp_os_restore()) {
+
+		ao_lisp_atoms = ao_lisp_poly_atom(os->ao_lisp_atoms);
+		ao_lisp_frame_global = ao_lisp_poly_frame(os->ao_lisp_globals);
+
+		/* Clear the eval global variabls */
+		ao_lisp_eval_clear_globals();
+
+		/* Reset the allocator */
+		ao_lisp_top = AO_LISP_POOL;
+		ao_lisp_collect();
+
+		/* Re-create the evaluator stack */
+		if (!ao_lisp_eval_restart())
+			return AO_LISP_NIL;
+		return _ao_lisp_atom_t;
+	}
+#endif
+	return AO_LISP_NIL;
+}