From: Keith Packard <keithp@keithp.com>
Date: Sun, 9 Sep 2012 20:50:56 +0000 (-0700)
Subject: altos: Try to get remote cmac time closer to reality
X-Git-Tag: 1.1~23
X-Git-Url: https://git.gag.com/?p=fw%2Faltos;a=commitdiff_plain;h=3fa71c497a5bf576974e70af06762f75734e6699

altos: Try to get remote cmac time closer to reality

Record the time after the packet was sent, but before the return
packet arrives to try and more closely approximate the time the packet
arrived at the other end.

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

diff --git a/src/drivers/ao_lco_func.c b/src/drivers/ao_lco_func.c
index 152b5d1b..99e58b76 100644
--- a/src/drivers/ao_lco_func.c
+++ b/src/drivers/ao_lco_func.c
@@ -28,18 +28,18 @@ ao_lco_query(uint16_t box, struct ao_pad_query *query, uint16_t *tick_offset)
 {
 	uint8_t		i;
 	int8_t		r;
-	uint16_t	time;
+	uint16_t	sent_time;
 
 	ao_mutex_get(&ao_lco_mutex);
-	time = ao_time();
-	command.tick = time;
+	command.tick = ao_time() - *tick_offset;
 	command.box = box;
 	command.cmd = AO_LAUNCH_QUERY;
 	command.channels = 0;
 	ao_radio_cmac_send(&command, sizeof (command));
-	r = ao_radio_cmac_recv(query, sizeof (*query), AO_MS_TO_TICKS(500));
+	sent_time = ao_time();
+	r = ao_radio_cmac_recv(query, sizeof (*query), AO_MS_TO_TICKS(20));
 	if (r == AO_RADIO_CMAC_OK)
-		*tick_offset = time - query->tick;
+		*tick_offset = sent_time - query->tick;
 	ao_mutex_put(&ao_lco_mutex);
 	return r;
 }