From: Mikko Rasa <tdb@tdb.fi>
Date: Sat, 9 Nov 2013 22:30:36 +0000 (+0200)
Subject: Avoid a race condition with the last bytes of an S88 read
X-Git-Url: http://git.tdb.fi/?p=model-railway-devices.git;a=commitdiff_plain;h=f0f49dd7ecb27635906557267a733dd8bdb8a9f7

Avoid a race condition with the last bytes of an S88 read
---

diff --git a/arducontrol/s88.c b/arducontrol/s88.c
index 142455a..bd53deb 100644
--- a/arducontrol/s88.c
+++ b/arducontrol/s88.c
@@ -28,8 +28,11 @@ void s88_init(void)
 
 void s88_check(void)
 {
+	/* Check remaining read count before ringbuffer fill.  If it is zero, no
+	more bytes are arriving in the buffer and the contents can be sent out. */
+	uint8_t rc = s88_read_count;
 	uint8_t count = ringbuffer_fill(s88_buffer);
-	if(count>=4 || (count>0 && !s88_read_count))
+	if(count>=4 || (count>0 && !rc))
 	{
 		uint8_t reply[10];