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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>
#include <ao_task.h>
#if HAS_SAMPLE_PROFILE
#include <ao_sample_profile.h>
#endif
#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 ao_arch_task_globals
ao_arch_task_globals
#endif
#define AO_CHECK_STACK 0
#if AO_CHECK_STACK
static uint8_t in_yield;
static inline void ao_check_stack(void) {
uint8_t q;
if (!in_yield && ao_cur_task && &q < &ao_cur_task->stack[0])
ao_panic(AO_PANIC_STACK);
}
#else
#define ao_check_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;
/*
* Construct a stack frame so that it will 'return'
* to the start of the task
*/
ao_arch_init_stack(task, start);
}
__xdata uint8_t ao_idle;
/* Task switching function. This must not use any stack variables */
void
ao_yield(void) ao_arch_naked_define
{
ao_arch_save_regs();
if (ao_cur_task_index == AO_NO_TASK_INDEX)
ao_cur_task_index = ao_num_tasks-1;
else
{
#if HAS_SAMPLE_PROFILE
uint16_t tick = ao_sample_profile_timer_value();
uint16_t run = tick - ao_cur_task->start;
if (run > ao_cur_task->max_run)
ao_cur_task->max_run = run;
++ao_cur_task->yields;
#endif
ao_arch_save_stack();
}
ao_arch_isr_stack();
#if AO_CHECK_STACK
in_yield = 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_last_task_index = ao_cur_task_index;
for (;;) {
++ao_cur_task_index;
if (ao_cur_task_index == ao_num_tasks)
ao_cur_task_index = 0;
ao_cur_task = ao_tasks[ao_cur_task_index];
/* Check for ready task */
if (ao_cur_task->wchan == NULL)
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)
break;
/* Enter lower power mode when there isn't anything to do */
if (ao_cur_task_index == ao_last_task_index)
ao_arch_cpu_idle();
}
#if HAS_SAMPLE_PROFILE
ao_cur_task->start = ao_sample_profile_timer_value();
#endif
}
#if AO_CHECK_STACK
cli();
in_yield = 0;
#endif
ao_arch_restore_stack();
}
uint8_t
ao_sleep(__xdata void *wchan)
{
ao_cur_task->wchan = wchan;
ao_yield();
if (ao_cur_task->wchan) {
ao_cur_task->wchan = NULL;
ao_cur_task->alarm = 0;
return 1;
}
return 0;
}
void
ao_wakeup(__xdata void *wchan)
{
uint8_t i;
ao_check_stack();
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_clear_alarm(void)
{
ao_cur_task->alarm = 0;
}
static __xdata uint8_t ao_forever;
void
ao_delay(uint16_t ticks)
{
ao_alarm(ticks);
ao_sleep(&ao_forever);
ao_clear_alarm();
}
void
ao_exit(void)
{
ao_arch_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;
__xdata struct ao_task *task;
for (i = 0; i < ao_num_tasks; i++) {
task = ao_tasks[i];
printf("%12s: wchan %04x\n",
task->name,
(int) task->wchan);
}
}
void
ao_start_scheduler(void)
{
ao_cur_task_index = AO_NO_TASK_INDEX;
ao_cur_task = NULL;
ao_yield();
}
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