altos: Replace ao_alarm/ao_clear_alarm with ao_sleep_for

Having arbitrary alarms firing in the middle of complicated device
logic makes no sense at all. Therefore only correct use of ao_alarm
and ao_clear_alarm was around a specific ao_sleep call, with correct
recovery in case the alarm fires.

This patch replaces all uses of ao_alarm/ao_sleep/ao_clear_alarm with
ao_sleep_for, a new function which takes the alarm timeout directly.

A few cases which weren't simply calling ao_sleep have been reworked
to pass the timeout value down to the place where sleep *is* being
called, and having that code deal with the return correctly.

Signed-off-by: Keith Packard <keithp@keithp.com>

6 files changed, 32 insertions, 16 deletions

diff --git a/src/kernel/ao_packet.h b/src/kernel/ao_packet.h
index b8426cf9..136609c3 100644
--- a/src/kernel/ao_packet.h
+++ b/src/kernel/ao_packet.h
@@ -54,7 +54,7 @@ void
 ao_packet_send(void);
 
 uint8_t
-ao_packet_recv(void);
+ao_packet_recv(uint16_t timeout);
 
 void
 ao_packet_flush(void);
diff --git a/src/kernel/ao_pyro.c b/src/kernel/ao_pyro.c
index 3044d565..43e73de4 100644
--- a/src/kernel/ao_pyro.c
+++ b/src/kernel/ao_pyro.c
@@ -375,9 +375,7 @@ ao_pyro(void)
 		ao_sleep(&ao_flight_state);
 
 	for (;;) {
-		ao_alarm(AO_MS_TO_TICKS(100));
-		ao_sleep(&ao_pyro_wakeup);
-		ao_clear_alarm();
+		ao_sleep_for(&ao_pyro_wakeup, AO_MS_TO_TICKS(100));
 		if (ao_flight_state >= ao_flight_landed)
 			break;
 		any_waiting = ao_pyro_check();
diff --git a/src/kernel/ao_serial.h b/src/kernel/ao_serial.h
index dbc9f8e4..e21643ac 100644
--- a/src/kernel/ao_serial.h
+++ b/src/kernel/ao_serial.h
@@ -35,7 +35,7 @@ int
 _ao_serial0_pollchar(void);
 
 uint8_t
-_ao_serial0_sleep(void);
+_ao_serial0_sleep_for(uint16_t timeout);
 
 void
 ao_serial0_putchar(char c);
@@ -58,7 +58,7 @@ int
 _ao_serial1_pollchar(void);
 
 uint8_t
-_ao_serial1_sleep(void);
+_ao_serial1_sleep_for(uint16_t timeout);
 
 void
 ao_serial1_putchar(char c);
@@ -81,7 +81,7 @@ int
 _ao_serial2_pollchar(void);
 
 uint8_t
-_ao_serial2_sleep(void);
+_ao_serial2_sleep_for(uint16_t timeout);
 
 void
 ao_serial2_putchar(char c);
@@ -104,7 +104,7 @@ int
 _ao_serial3_pollchar(void);
 
 uint8_t
-_ao_serial3_sleep(void);
+_ao_serial3_sleep_for(uint16_t timeout);
 
 void
 ao_serial3_putchar(char c);
diff --git a/src/kernel/ao_task.c b/src/kernel/ao_task.c
index bafb4943..1ecdd7dd 100644
--- a/src/kernel/ao_task.c
+++ b/src/kernel/ao_task.c
@@ -450,7 +450,7 @@ ao_wakeup(__xdata void *wchan) __reentrant
 	ao_check_stack();
 }
 
-void
+static void
 ao_alarm(uint16_t delay)
 {
 #if HAS_TASK_QUEUE
@@ -468,7 +468,7 @@ ao_alarm(uint16_t delay)
 #endif
 }
 
-void
+static void
 ao_clear_alarm(void)
 {
 #if HAS_TASK_QUEUE
@@ -483,14 +483,24 @@ ao_clear_alarm(void)
 #endif
 }
 
+uint8_t
+ao_sleep_for(__xdata void *wchan, uint16_t timeout)
+{
+	uint8_t	ret;
+	if (timeout)
+		ao_alarm(timeout);
+	ret = ao_sleep(wchan);
+	if (timeout)
+		ao_clear_alarm();
+	return ret;
+}
+
 static __xdata uint8_t ao_forever;
 
 void
 ao_delay(uint16_t ticks)
 {
-	ao_alarm(ticks);
-	ao_sleep(&ao_forever);
-	ao_clear_alarm();
+	ao_sleep_for(&ao_forever, ticks);
 }
 
 void
diff --git a/src/kernel/ao_task.h b/src/kernel/ao_task.h
index 9c56b480..c6bec0e3 100644
--- a/src/kernel/ao_task.h
+++ b/src/kernel/ao_task.h
@@ -68,10 +68,19 @@ extern __data uint8_t ao_task_minimize_latency;	/* Reduce IRQ latency */
 uint8_t
 ao_sleep(__xdata void *wchan);
 
+/* Suspend the current task until wchan is awoken or the timeout
+ * expires. returns:
+ *  0 on normal wake
+ *  1 on alarm
+ */
+uint8_t
+ao_sleep_for(__xdata void *wchan, uint16_t timeout);
+
 /* Wake all tasks sleeping on wchan */
 void
 ao_wakeup(__xdata void *wchan) __reentrant;
 
+#if 0
 /* set an alarm to go off in 'delay' ticks */
 void
 ao_alarm(uint16_t delay);
@@ -79,6 +88,7 @@ ao_alarm(uint16_t delay);
 /* Clear any pending alarm */
 void
 ao_clear_alarm(void);
+#endif
 
 /* Yield the processor to another task */
 void
diff --git a/src/kernel/ao_telemetry.c b/src/kernel/ao_telemetry.c
index e2197f7a..854ac898 100644
--- a/src/kernel/ao_telemetry.c
+++ b/src/kernel/ao_telemetry.c
@@ -486,9 +486,7 @@ ao_telemetry(void)
 #endif /* HAS_APRS */
 			delay = time - ao_time();
 			if (delay > 0) {
-				ao_alarm(delay);
-				ao_sleep(&telemetry);
-				ao_clear_alarm();
+				ao_sleep_for(&telemetry, delay);
 			}
 		}
 	}