From 54b6a0abce85e4d28023e5bd4febd9940cc51ca5 Mon Sep 17 00:00:00 2001
From: Steve Underwood <steveu@coppice.org>
Date: Wed, 9 Jul 2014 10:18:00 +0800
Subject: [PATCH] Added explanatory comment on a recent change.
---
libs/spandsp/src/t38_gateway.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/libs/spandsp/src/t38_gateway.c b/libs/spandsp/src/t38_gateway.c
index 6df86775bb..1e6a19d0c2 100644
--- a/libs/spandsp/src/t38_gateway.c
+++ b/libs/spandsp/src/t38_gateway.c
@@ -1941,6 +1941,11 @@ static void t38_hdlc_rx_put_bit(hdlc_rx_state_t *t, int new_bit)
if (t->buffer[0] != 0xFF || (t->buffer[1] & 0xEF) != 0x03)
{
/* Abandon the frame, and wait for the next flag octet. */
+ /* If this is a real frame, where one of these first two octets has a bit
+ error, we will fail to forward the frame with a CRC error, as we do for
+ other bad framess. This will affect the timing of what goes forward.
+ Hopefully such timing changes will have less frequent bad effects than
+ the consequences of a bad bit stream simulating an HDLC frame start. */
span_log(&s->logging, SPAN_LOG_FLOW, "Bad HDLC frame header. Abandoning frame.\n");
t->flags_seen = t->framing_ok_threshold - 1;
t->len = 0;