diff options
Diffstat (limited to 'src/core/ao_task.c')
| -rw-r--r-- | src/core/ao_task.c | 177 |
1 files changed, 177 insertions, 0 deletions
diff --git a/src/core/ao_task.c b/src/core/ao_task.c new file mode 100644 index 00000000..a19a6a6f --- /dev/null +++ b/src/core/ao_task.c @@ -0,0 +1,177 @@ +/* + * 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 ao_arch_task_globals +ao_arch_task_globals +#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); +} + +/* 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 + { + ao_arch_save_stack(); + } + + ao_arch_isr_stack(); + + /* 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; + } + + /* Enter lower power mode when there isn't anything to do */ + if (ao_next_task_index == ao_cur_task_index) { + ao_arch_cpu_idle(); + } + } + } + ao_arch_restore_stack(); +} + +uint8_t +ao_sleep(__xdata void *wchan) +{ + ao_arch_critical( + ao_cur_task->wchan = wchan; + ); + ao_yield(); + 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_clear_alarm(void) +{ + ao_cur_task->alarm = 0; +} + +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, + (int16_t) task->wchan); + } +} + +void +ao_start_scheduler(void) +{ + ao_cur_task_index = AO_NO_TASK_INDEX; + ao_cur_task = NULL; + ao_yield(); +} |