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-rw-r--r--src-avr/ao_task.c347
1 files changed, 347 insertions, 0 deletions
diff --git a/src-avr/ao_task.c b/src-avr/ao_task.c
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+/*
+ * Copyright © 2009 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.h"
+
+#define AO_NO_TASK_INDEX 0xff
+
+__xdata struct ao_task * __xdata ao_tasks[AO_NUM_TASKS];
+__data uint8_t ao_num_tasks;
+__data uint8_t ao_cur_task_index;
+__xdata struct ao_task *__data ao_cur_task;
+
+#ifdef AVR
+
+#define PUSH8(stack, val) (*((stack)--) = (val))
+
+static void
+ao_init_stack(__xdata struct ao_task *task, void (*start)(void))
+{
+ uint8_t *stack = task->stack + AO_STACK_SIZE - 1;
+ uint16_t a = (uint16_t) start;
+ int i;
+
+ /* Return address */
+ PUSH8(stack, a);
+ PUSH8(stack, (a >> 8));
+
+ /* Clear register values */
+ i = 32;
+ while (i--)
+ PUSH8(stack, 0);
+
+ /* SREG with interrupts enabled */
+ PUSH8(stack, 0x80);
+ task->stack_count = stack - task->stack;
+}
+#else
+static void
+ao_init_stack(__xdata struct ao_task *task, void (*start)(void))
+{
+ uint8_t __xdata *stack = task->stack;
+ /*
+ * Construct a stack frame so that it will 'return'
+ * to the start of the task
+ */
+
+ *stack++ = ((uint16_t) start);
+ *stack++ = ((uint16_t) start) >> 8;
+
+ /* and the stuff saved by ao_switch */
+ *stack++ = 0; /* acc */
+ *stack++ = 0x80; /* IE */
+ *stack++ = 0; /* DPL */
+ *stack++ = 0; /* DPH */
+ *stack++ = 0; /* B */
+ *stack++ = 0; /* R2 */
+ *stack++ = 0; /* R3 */
+ *stack++ = 0; /* R4 */
+ *stack++ = 0; /* R5 */
+ *stack++ = 0; /* R6 */
+ *stack++ = 0; /* R7 */
+ *stack++ = 0; /* R0 */
+ *stack++ = 0; /* R1 */
+ *stack++ = 0; /* PSW */
+ *stack++ = 0; /* BP */
+ task->stack_count = stack - task->stack;
+}
+#endif
+
+void
+ao_add_task(__xdata struct ao_task * task, void (*start)(void), __code char *name) __reentrant
+{
+ uint8_t task_id;
+ uint8_t t;
+ if (ao_num_tasks == AO_NUM_TASKS)
+ ao_panic(AO_PANIC_NO_TASK);
+ for (task_id = 1; task_id != 0; task_id++) {
+ for (t = 0; t < ao_num_tasks; t++)
+ if (ao_tasks[t]->task_id == task_id)
+ break;
+ if (t == ao_num_tasks)
+ break;
+ }
+ ao_tasks[ao_num_tasks++] = task;
+ task->task_id = task_id;
+ task->name = name;
+ task->wchan = NULL;
+ ao_init_stack(task, start);
+}
+
+/* Task switching function. This must not use any stack variables */
+void
+ao_yield(void) __naked
+{
+#ifdef AVR
+ asm("push r31" "\n\t" "push r30");
+ asm("push r29" "\n\t" "push r28" "\n\t" "push r27" "\n\t" "push r26" "\n\t" "push r25");
+ asm("push r24" "\n\t" "push r23" "\n\t" "push r22" "\n\t" "push r21" "\n\t" "push r20");
+ asm("push r19" "\n\t" "push r18" "\n\t" "push r17" "\n\t" "push r16" "\n\t" "push r15");
+ asm("push r14" "\n\t" "push r13" "\n\t" "push r12" "\n\t" "push r11" "\n\t" "push r10");
+ asm("push r9" "\n\t" "push r8" "\n\t" "push r7" "\n\t" "push r6" "\n\t" "push r5");
+ asm("push r4" "\n\t" "push r3" "\n\t" "push r2" "\n\t" "push r1" "\n\t" "push r0");
+ asm("in r0, __SREG__" "\n\t" "push r0");
+ sei();
+#else
+ /* Save current context */
+ _asm
+ /* Push ACC first, as when restoring the context it must be restored
+ * last (it is used to set the IE register). */
+ push ACC
+ /* Store the IE register then enable interrupts. */
+ push _IEN0
+ setb _EA
+ push DPL
+ push DPH
+ push b
+ push ar2
+ push ar3
+ push ar4
+ push ar5
+ push ar6
+ push ar7
+ push ar0
+ push ar1
+ push PSW
+ _endasm;
+ PSW = 0;
+ _asm
+ push _bp
+ _endasm;
+#endif
+
+ if (ao_cur_task_index == AO_NO_TASK_INDEX)
+ ao_cur_task_index = ao_num_tasks-1;
+ else
+ {
+#ifdef AVR
+ uint8_t sp_l, sp_h;
+ uint8_t *sp;
+ asm("in %0,__SP_L__" : "=&r" (sp_l) );
+ asm("in %0,__SP_H__" : "=&r" (sp_h) );
+ sp = (uint8_t *) ((uint16_t) sp_l | ((uint16_t) sp_h << 8));
+ ao_cur_task->stack_count = sp - ao_cur_task->stack;
+#else
+ uint8_t stack_len;
+ __data uint8_t *stack_ptr;
+ __xdata uint8_t *save_ptr;
+ /* Save the current stack */
+ stack_len = SP - (AO_STACK_START - 1);
+ ao_cur_task->stack_count = stack_len;
+ stack_ptr = (uint8_t __data *) AO_STACK_START;
+ save_ptr = (uint8_t __xdata *) ao_cur_task->stack;
+ do
+ *save_ptr++ = *stack_ptr++;
+ while (--stack_len);
+#endif
+ }
+
+#ifndef AVR
+ /* Empty the stack; might as well let interrupts have the whole thing */
+ SP = AO_STACK_START - 1;
+#endif
+
+ /* Find a task to run. If there isn't any runnable task,
+ * this loop will run forever, which is just fine
+ */
+ {
+ __pdata uint8_t ao_next_task_index = ao_cur_task_index;
+ for (;;) {
+ ++ao_next_task_index;
+ if (ao_next_task_index == ao_num_tasks)
+ ao_next_task_index = 0;
+
+ ao_cur_task = ao_tasks[ao_next_task_index];
+ if (ao_cur_task->wchan == NULL) {
+ ao_cur_task_index = ao_next_task_index;
+ break;
+ }
+
+ /* Check if the alarm is set for a time which has passed */
+ if (ao_cur_task->alarm &&
+ (int16_t) (ao_time() - ao_cur_task->alarm) >= 0) {
+ ao_cur_task_index = ao_next_task_index;
+ break;
+ }
+
+#ifdef AVR
+#else
+ /* Enter lower power mode when there isn't anything to do */
+ if (ao_next_task_index == ao_cur_task_index)
+ PCON = PCON_IDLE;
+#endif
+ }
+ }
+
+#ifdef AVR
+ {
+ uint8_t *sp = (ao_cur_task->stack + ao_cur_task->stack_count);
+ uint8_t sp_l, sp_h;
+ sp_l = (uint16_t) sp;
+ sp_h = ((uint16_t) sp) >> 8;
+ asm("out __SP_H__,%0" : : "r" (sp_h) );
+ asm("out __SP_L__,%0" : : "r" (sp_l) );
+ asm("pop r0" "\n\t"
+ "out __SREG__, r0");
+ asm("pop r0" "\n\t" "pop r1" "\n\t" "pop r2" "\n\t" "pop r3" "\n\t" "pop r4");
+ asm("pop r5" "\n\t" "pop r6" "\n\t" "pop r7" "\n\t" "pop r8" "\n\t" "pop r9");
+ asm("pop r10" "\n\t" "pop r11" "\n\t" "pop r12" "\n\t" "pop r13" "\n\t" "pop r14");
+ asm("pop r15" "\n\t" "pop r16" "\n\t" "pop r17" "\n\t" "pop r18" "\n\t" "pop r19");
+ asm("pop r20" "\n\t" "pop r21" "\n\t" "pop r22" "\n\t" "pop r23" "\n\t" "pop r24");
+ asm("pop r25" "\n\t" "pop r26" "\n\t" "pop r27" "\n\t" "pop r28" "\n\t" "pop r29");
+ asm("pop r30" "\n\t" "pop r31");
+ asm("ret");
+ }
+#else
+ {
+ uint8_t stack_len;
+ __data uint8_t *stack_ptr;
+ __xdata uint8_t *save_ptr;
+
+ /* Restore the old stack */
+ stack_len = ao_cur_task->stack_count;
+ SP = AO_STACK_START - 1 + stack_len;
+
+ stack_ptr = (uint8_t __data *) AO_STACK_START;
+ save_ptr = (uint8_t __xdata *) ao_cur_task->stack;
+ do
+ *stack_ptr++ = *save_ptr++;
+ while (--stack_len);
+ }
+
+ _asm
+ pop _bp
+ pop PSW
+ pop ar1
+ pop ar0
+ pop ar7
+ pop ar6
+ pop ar5
+ pop ar4
+ pop ar3
+ pop ar2
+ pop b
+ pop DPH
+ pop DPL
+ /* The next byte of the stack is the IE register. Only the global
+ enable bit forms part of the task context. Pop off the IE then set
+ the global enable bit to match that of the stored IE register. */
+ pop ACC
+ JB ACC.7,0098$
+ CLR _EA
+ LJMP 0099$
+ 0098$:
+ SETB _EA
+ 0099$:
+ /* Finally pop off the ACC, which was the first register saved. */
+ pop ACC
+ ret
+ _endasm;
+#endif
+}
+
+uint8_t
+ao_sleep(__xdata void *wchan)
+{
+ __critical {
+ ao_cur_task->wchan = wchan;
+ }
+ ao_yield();
+ ao_cur_task->alarm = 0;
+ if (ao_cur_task->wchan) {
+ ao_cur_task->wchan = NULL;
+ return 1;
+ }
+ return 0;
+}
+
+void
+ao_wakeup(__xdata void *wchan)
+{
+ uint8_t i;
+
+ for (i = 0; i < ao_num_tasks; i++)
+ if (ao_tasks[i]->wchan == wchan)
+ ao_tasks[i]->wchan = NULL;
+}
+
+void
+ao_alarm(uint16_t delay)
+{
+ /* Make sure we sleep *at least* delay ticks, which means adding
+ * one to account for the fact that we may be close to the next tick
+ */
+ if (!(ao_cur_task->alarm = ao_time() + delay + 1))
+ ao_cur_task->alarm = 1;
+}
+
+void
+ao_exit(void) __critical
+{
+ uint8_t i;
+ ao_num_tasks--;
+ for (i = ao_cur_task_index; i < ao_num_tasks; i++)
+ ao_tasks[i] = ao_tasks[i+1];
+ ao_cur_task_index = AO_NO_TASK_INDEX;
+ ao_yield();
+ /* we'll never get back here */
+}
+
+void
+ao_task_info(void)
+{
+ uint8_t i;
+ uint8_t pc_loc;
+ __xdata struct ao_task *task;
+
+ for (i = 0; i < ao_num_tasks; i++) {
+ task = ao_tasks[i];
+ pc_loc = task->stack_count - 17;
+ printf("%12s: wchan %04x pc %04x\n",
+ task->name,
+ (int16_t) task->wchan,
+ (task->stack[pc_loc]) | (task->stack[pc_loc+1] << 8));
+ }
+}
+
+void
+ao_start_scheduler(void)
+{
+ ao_cur_task_index = AO_NO_TASK_INDEX;
+ ao_cur_task = NULL;
+ ao_yield();
+}
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