1 files changed, 102 insertions, 0 deletions
diff --git a/openbsc/include/openbsc/subchan_demux.h b/openbsc/include/openbsc/subchan_demux.h
new file mode 100644
index 000000000..9661b0481
--- /dev/null
+++ b/openbsc/include/openbsc/subchan_demux.h
@@ -0,0 +1,102 @@
+#ifndef _SUBCH_DEMUX_H
+#define _SUBCH_DEMUX_H
+/* A E1 sub-channel (de)multiplexer with TRAU frame sync */
+
+/* (C) 2009 by Harald Welte <laforge@gnumonks.org>
+ * All Rights Reserved
+ *
+ * This program 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 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ */
+
+#include <sys/types.h>
+#include <openbsc/linuxlist.h>
+
+#define NR_SUBCH	4
+#define TRAU_FRAME_SIZE	40
+#define TRAU_FRAME_BITS	(TRAU_FRAME_SIZE*8)
+
+/***********************************************************************/
+/* DEMULTIPLEXER */
+/***********************************************************************/
+
+struct demux_subch {
+	u_int8_t out_bitbuf[TRAU_FRAME_BITS];
+	u_int16_t out_idx; /* next bit to be written in out_bitbuf */
+	/* number of consecutive zeros that we have received (for sync) */
+	unsigned int consecutive_zeros;
+	/* are we in TRAU frame sync or not? */
+	unsigned int in_sync;
+};
+
+struct subch_demux {
+	/* bitmask of currently active subchannels */
+	u_int8_t chan_activ;
+	/* one demux_subch struct for every subchannel */
+	struct demux_subch subch[NR_SUBCH];
+	/* callback to be called once we have received a complete
+	 * frame on a given subchannel */
+	int (*out_cb)(struct subch_demux *dmx, int ch, u_int8_t *data, int len,
+		      void *);
+	/* user-provided data, transparently passed to out_cb() */
+	void *data;
+};
+
+/* initialize one demultiplexer instance */
+int subch_demux_init(struct subch_demux *dmx);
+
+/* feed 'len' number of muxed bytes into the demultiplexer */
+int subch_demux_in(struct subch_demux *dmx, u_int8_t *data, int len);
+
+/* activate decoding/processing for one subchannel */
+int subch_demux_activate(struct subch_demux *dmx, int subch);
+
+/* deactivate decoding/processing for one subchannel */
+int subch_demux_deactivate(struct subch_demux *dmx, int subch);
+
+/***********************************************************************/
+/* MULTIPLEXER */
+/***********************************************************************/
+
+/* one element in the tx_queue of a muxer sub-channel */
+struct subch_txq_entry {
+	struct llist_head list;
+
+	unsigned int bit_len;	/* total number of bits in 'bits' */
+	unsigned int next_bit;	/* next bit to be transmitted */
+
+	u_int8_t bits[0];	/* one bit per byte */
+};
+
+struct mux_subch {
+	struct llist_head tx_queue;
+};
+
+/* structure representing one instance of the subchannel muxer */
+struct subch_mux {
+	struct mux_subch subch[NR_SUBCH];
+};
+
+/* initialize a subchannel muxer instance */
+int subchan_mux_init(struct subch_mux *mx);
+
+/* request the output of 'len' multiplexed bytes */
+int subchan_mux_out(struct subch_mux *mx, u_int8_t *data, int len);
+
+/* enqueue some data into one sub-channel of the muxer */
+int subchan_mux_enqueue(struct subch_mux *mx, int s_nr, const u_int8_t *data,
+			int len);
+
+#endif /* _SUBCH_DEMUX_H */