2 * Copyright © 2009 Keith Packard <keithp@keithp.com>
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; version 2 of the License.
8 * This program is distributed in the hope that it will be useful, but
9 * WITHOUT ANY WARRANTY; without even the implied warranty of
10 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
11 * General Public License for more details.
13 * You should have received a copy of the GNU General Public License along
14 * with this program; if not, write to the Free Software Foundation, Inc.,
15 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
20 #define AO_NO_TASK_INDEX 0xff
22 __xdata struct ao_task * __xdata ao_tasks[AO_NUM_TASKS];
23 __data uint8_t ao_num_tasks;
24 __data uint8_t ao_cur_task_index;
25 __xdata struct ao_task *__data ao_cur_task;
28 ao_add_task(__xdata struct ao_task * task, void (*start)(void), __code char *name) __reentrant
30 uint8_t __xdata *stack;
33 if (ao_num_tasks == AO_NUM_TASKS)
34 ao_panic(AO_PANIC_NO_TASK);
35 for (task_id = 1; task_id != 0; task_id++) {
36 for (t = 0; t < ao_num_tasks; t++)
37 if (ao_tasks[t]->task_id == task_id)
39 if (t == ao_num_tasks)
42 ao_tasks[ao_num_tasks++] = task;
43 task->task_id = task_id;
46 * Construct a stack frame so that it will 'return'
47 * to the start of the task
51 *stack++ = ((uint16_t) start);
52 *stack++ = ((uint16_t) start) >> 8;
54 /* and the stuff saved by ao_switch */
55 *stack++ = 0; /* acc */
56 *stack++ = 0x80; /* IE */
57 *stack++ = 0; /* DPL */
58 *stack++ = 0; /* DPH */
60 *stack++ = 0; /* R2 */
61 *stack++ = 0; /* R3 */
62 *stack++ = 0; /* R4 */
63 *stack++ = 0; /* R5 */
64 *stack++ = 0; /* R6 */
65 *stack++ = 0; /* R7 */
66 *stack++ = 0; /* R0 */
67 *stack++ = 0; /* R1 */
68 *stack++ = 0; /* PSW */
69 *stack++ = 0; /* BP */
70 task->stack_count = stack - task->stack;
74 /* Task switching function. This must not use any stack variables */
79 /* Save current context */
81 /* Push ACC first, as when restoring the context it must be restored
82 * last (it is used to set the IE register). */
84 /* Store the IE register then enable interrupts. */
105 if (ao_cur_task_index == AO_NO_TASK_INDEX)
106 ao_cur_task_index = ao_num_tasks-1;
110 __data uint8_t *stack_ptr;
111 __xdata uint8_t *save_ptr;
112 /* Save the current stack */
113 stack_len = SP - (AO_STACK_START - 1);
114 ao_cur_task->stack_count = stack_len;
115 stack_ptr = (uint8_t __data *) AO_STACK_START;
116 save_ptr = (uint8_t __xdata *) ao_cur_task->stack;
118 *save_ptr++ = *stack_ptr++;
122 /* Empty the stack; might as well let interrupts have the whole thing */
123 SP = AO_STACK_START - 1;
125 /* Find a task to run. If there isn't any runnable task,
126 * this loop will run forever, which is just fine
129 __pdata uint8_t ao_next_task_index = ao_cur_task_index;
131 ++ao_next_task_index;
132 if (ao_next_task_index == ao_num_tasks)
133 ao_next_task_index = 0;
135 ao_cur_task = ao_tasks[ao_next_task_index];
136 if (ao_cur_task->wchan == NULL) {
137 ao_cur_task_index = ao_next_task_index;
141 /* Check if the alarm is set for a time which has passed */
142 if (ao_cur_task->alarm &&
143 (int16_t) (ao_time() - ao_cur_task->alarm) >= 0) {
144 ao_cur_task_index = ao_next_task_index;
148 /* Enter lower power mode when there isn't anything to do */
149 if (ao_next_task_index == ao_cur_task_index)
156 __data uint8_t *stack_ptr;
157 __xdata uint8_t *save_ptr;
159 /* Restore the old stack */
160 stack_len = ao_cur_task->stack_count;
161 SP = AO_STACK_START - 1 + stack_len;
163 stack_ptr = (uint8_t __data *) AO_STACK_START;
164 save_ptr = (uint8_t __xdata *) ao_cur_task->stack;
166 *stack_ptr++ = *save_ptr++;
184 /* The next byte of the stack is the IE register. Only the global
185 enable bit forms part of the task context. Pop off the IE then set
186 the global enable bit to match that of the stored IE register. */
194 /* Finally pop off the ACC, which was the first register saved. */
201 ao_sleep(__xdata void *wchan)
204 ao_cur_task->wchan = wchan;
207 ao_cur_task->alarm = 0;
208 if (ao_cur_task->wchan) {
209 ao_cur_task->wchan = NULL;
216 ao_wakeup(__xdata void *wchan)
220 for (i = 0; i < ao_num_tasks; i++)
221 if (ao_tasks[i]->wchan == wchan)
222 ao_tasks[i]->wchan = NULL;
226 ao_alarm(uint16_t delay)
228 /* Make sure we sleep *at least* delay ticks, which means adding
229 * one to account for the fact that we may be close to the next tick
231 if (!(ao_cur_task->alarm = ao_time() + delay + 1))
232 ao_cur_task->alarm = 1;
236 ao_exit(void) __critical
240 for (i = ao_cur_task_index; i < ao_num_tasks; i++)
241 ao_tasks[i] = ao_tasks[i+1];
242 ao_cur_task_index = AO_NO_TASK_INDEX;
244 /* we'll never get back here */
252 __xdata struct ao_task *task;
254 for (i = 0; i < ao_num_tasks; i++) {
256 pc_loc = task->stack_count - 17;
257 printf("%12s: wchan %04x pc %04x\n",
259 (int16_t) task->wchan,
260 (task->stack[pc_loc]) | (task->stack[pc_loc+1] << 8));
265 ao_start_scheduler(void)
267 ao_cur_task_index = AO_NO_TASK_INDEX;