# HG changeset patch
# User Mychaela Falconia <falcon@freecalypso.org>
# Date 1718666059 0
# Node ID aaf4dec8bee0e4ed81e41a1ddd883fbb17b9c2bd
# Parent  dc7249923b3a9d76e4fbced280330534fd975ed7
libgsmhr1: implement perfect SID detection

diff -r dc7249923b3a -r aaf4dec8bee0 libgsmhr1/Makefile
--- a/libgsmhr1/Makefile	Mon Jun 17 23:00:57 2024 +0000
+++ b/libgsmhr1/Makefile	Mon Jun 17 23:14:19 2024 +0000
@@ -1,4 +1,5 @@
-OBJS=	pack_frame.o rtp_in.o twts002_in.o twts002_out.o unpack_frame.o
+OBJS=	pack_frame.o rtp_in.o sid_detect.o twts002_in.o twts002_out.o \
+	unpack_frame.o
 HDRS=	tw_gsmhr.h
 LIB=	libgsmhr1.a
 
diff -r dc7249923b3a -r aaf4dec8bee0 libgsmhr1/sid_detect.c
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libgsmhr1/sid_detect.c	Mon Jun 17 23:14:19 2024 +0000
@@ -0,0 +1,22 @@
+/*
+ * The function in this module implements detection of perfect, error-free
+ * HRv1 SID frames in TS 101 318 raw packed format.  If SID is detected,
+ * the return value is 2: the code for valid SID per GSM 06.41.
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include "tw_gsmhr.h"
+
+int gsmhr_ts101318_is_perfect_sid(const uint8_t *payload)
+{
+	static const uint8_t all_ff_bytes[9] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
+						0xFF, 0xFF, 0xFF, 0xFF};
+
+	if ((payload[4] & 0x7F) != 0x7F)
+		return 0;
+	if (memcmp(payload + 5, all_ff_bytes, 9) == 0)
+		return 2;
+	else
+		return 0;
+}