Add ao_alarm

2 files changed, 33 insertions, 3 deletions

diff --git a/src/ao.h b/src/ao.h
index 84e92f35..b90befe5 100644
--- a/src/ao.h
+++ b/src/ao.h
@@ -40,6 +40,7 @@
 /* An AltOS task */
 struct ao_task {
 	__xdata void *wchan;		/* current wait channel (NULL if running) */
+	uint16_t alarm;			/* abort ao_sleep time */
 	uint8_t	stack_count;		/* amount of saved stack */
 	uint8_t task_id;		/* index in the task array */
 	__code char *name;		/* task name */
@@ -55,8 +56,12 @@ extern __xdata struct ao_task *__data ao_cur_task;
  ao_task.c
  */
 
-/* Suspend the current task until wchan is awoken */
-void
+/* Suspend the current task until wchan is awoken.
+ * returns:
+ *  0 on normal wake
+ *  1 on alarm
+ */
+uint8_t
 ao_sleep(__xdata void *wchan);
 
 /* Wake all tasks sleeping on wchan */
@@ -67,6 +72,10 @@ ao_wakeup(__xdata void *wchan);
 void
 ao_wake_task(__xdata struct ao_task *task);
 
+/* set an alarm to go off in 'delay' ticks */
+void
+ao_alarm(uint16_t delay);
+
 /* Yield the processor to another task */
 void
 ao_yield(void) _naked;
diff --git a/src/ao_task.c b/src/ao_task.c
index 136444b0..14aa84c8 100644
--- a/src/ao_task.c
+++ b/src/ao_task.c
@@ -129,6 +129,13 @@ ao_yield(void) _naked
 				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)
 				PCON = PCON_IDLE;
@@ -181,13 +188,20 @@ ao_yield(void) _naked
 	_endasm;
 }
 
-void
+uint8_t
 ao_sleep(__xdata void *wchan)
 {
 	__critical {
 		ao_cur_task->wchan = wchan;
 	}
 	ao_yield();
+	if (ao_cur_task->wchan) {
+		ao_cur_task->wchan = NULL;
+		ao_cur_task->alarm = 0;
+		return 1;
+	}
+	ao_cur_task->alarm = 0;
+	return 0;
 }
 
 void
@@ -201,6 +215,13 @@ ao_wakeup(__xdata void *wchan)
 }
 
 void
+ao_alarm(uint16_t delay)
+{
+	if (!(ao_cur_task->alarm = ao_time() + delay))
+		ao_cur_task->alarm = 1;
+}
+
+void
 ao_wake_task(__xdata struct ao_task *task)
 {
 	task->wchan = NULL;