format: Add support for classic .gsm file/frame format

Signed-off-by: Sylvain Munaut <tnt@246tNt.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/src/fmt_gsm.c b/src/fmt_gsm.c
new file mode 100644
index 0000000..04ca062
--- /dev/null
+++ b/src/fmt_gsm.c
@@ -0,0 +1,59 @@
+/* Classic .gsm files for FR */
+
+/*
+ * This file is part of gapk (GSM Audio Pocket Knife).
+ *
+ * gapk is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * gapk is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with gapk.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <gapk/codecs.h>
+#include <gapk/formats.h>
+
+
+#define GSM_MAGIC 0xd
+
+static int
+gsm_from_canon(uint8_t *dst, const uint8_t *src)
+{
+	int i;
+
+	dst[0] = (GSM_MAGIC << 4) | (src[0] >> 4);
+	for (i=1; i<33; i++)
+		dst[i] = (src[i-1] << 4) | (src[i] >> 4);
+
+	return 0;
+}
+
+static int
+gsm_to_canon(uint8_t *dst, const uint8_t *src)
+{
+	int i;
+
+	for (i=0; i<32; i++)
+		dst[i] = (src[i] << 4) | (src[i+1] >> 4);
+	dst[32] = src[32] << 4;
+
+	return 0;
+}
+
+const struct format_desc fmt_gsm = {
+	.type			= FMT_GSM,
+	.codec_type		= CODEC_FR,
+	.name			= "gsm",
+	.description		= "Classic .gsm file format",
+
+	.frame_len		= 33,
+	.conv_from_canon	= gsm_from_canon,
+	.conv_to_canon		= gsm_to_canon,
+};