From 7a743398cf4738e58a7a57f94dc079a6c529829d Mon Sep 17 00:00:00 2001
From: leo <leo@brix.(none)>
Date: Wed, 20 Feb 2008 02:28:51 +0000
Subject: channel decoding (gsmstack)

---
 gsm-tvoid/src/lib/gsmstack.c | 74 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)
 create mode 100644 gsm-tvoid/src/lib/gsmstack.c

(limited to 'gsm-tvoid/src/lib/gsmstack.c')

diff --git a/gsm-tvoid/src/lib/gsmstack.c b/gsm-tvoid/src/lib/gsmstack.c
new file mode 100644
index 0000000..9fc4868
--- /dev/null
+++ b/gsm-tvoid/src/lib/gsmstack.c
@@ -0,0 +1,74 @@
+/*
+ * Invoke gsmstack() with any kind of burst. Automaticly decode and retrieve
+ * information.
+ */
+#include "system.h"
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include "gsmstack.h"
+#include "gsm_constants.h"
+#include "interleave.h"
+#include "sch.h"
+
+INTERLEAVE_CTX ictx;
+
+static void
+diff_decode(char *dst, char *src, int len)
+{
+	const unsigned char *end = src + len;
+	unsigned char last;
+
+	src += 3;
+	last = 0;
+	memset(dst, 0, 3);
+	dst += 3;
+
+	while (src < end)
+	{
+		*dst = !*src ^ last;
+		last = *dst;
+		src++;
+		dst++;
+	}
+}
+
+/*
+ * Initialize a new GSMSTACK context.
+ */
+int
+GS_new(GS_CTX *ctx)
+{
+	memset(ctx, 0, sizeof *ctx);
+	interleave_init(&ictx, 456, 114);
+
+	return 0;
+}
+
+/*
+ * 156 bit
+ */
+int
+GS_process(GS_CTX *ctx, int ts, int type, char *data)
+{
+	int fn;
+	int bsic;
+	int ret;
+	char buf[156];
+
+	diff_decode(buf, data, 156);
+
+	switch (type)
+	{
+	case SCH:
+		ret = decode_sch(buf, &fn, &bsic);
+		if (ret != 0)
+			break;
+		DEBUGF("FN %d, BSIC %d\n", fn, bsic);
+		break;
+	case NORMAL:
+		break;
+	}
+}
+
+
-- 
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