Started work on VHF framer/deframer

git-svn-id: https://svn.code.sf.net/p/freetel/code@2698 01035d8c-6547-0410-b346-abe4f91aad63

diff --git a/codec2-dev/src/freedv_vhf_framing.h b/codec2-dev/src/freedv_vhf_framing.h
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+/*---------------------------------------------------------------------------*\
+
+  FILE........: freedv_vhf_framing.h
+  AUTHOR......: Brady O'Brien
+  DATE CREATED: 11 February 2016
+
+  Framer and deframer for VHF FreeDV modes 'A' and 'B'
+  Currently designed for-
+  * 40ms ota modem frames
+  * 40ms Codec2 1300 frames
+  * 52 bits of Codec2 per frame
+  * 16 bits of unique word per frame
+  * 28 'spare' bits per frame
+  *  - 4 spare bits at front and end of frame (8 total) for padding
+  *  - 20 'protocol' bits, either for higher layers of 'protocol' or
+  *  - 18 'protocol' bits and 2 vericode sidechannel bits
+\*---------------------------------------------------------------------------*/
+
+/*
+  Copyright (C) 2016 David Rowe
+
+  All rights reserved.
+
+  This program is free software; you can redistribute it and/or modify
+  it under the terms of the GNU Lesser General Public License version 2.1, as
+  published by the Free Software Foundation.  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 Lesser General Public License
+  along with this program; if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#ifndef _FREEDV_VHF_FRAMING_H
+#define _FREEDV_VHF_FRAMING_H
+
+/* Standard frame type */
+#define FREEDV_VHF_FRAME_A 1
+
+/* Unique word for A type frame */
+#define FREEDV_VHF_FRAME_A_UW {0,1,1,0,0,1,1,1,1,0,1,0,1,1,0,1}
+
+/* States */
+/* TODO: Move into the C file */
+#define ST_NOSYNC 0 /* Not synchronized */
+#define ST_SYNC 1   /* Synchronized */
+
+struct freedv_vhf_deframer {
+    int ftype;          /* Type of frame to be looking for */
+    int state;          /* State of deframer */
+    uint8_t * bits;     /* Bits currently being decanted */
+    int bitptr;         /* Pointer into circular bit buffer */
+    int miss_cnt;       /* How many UWs have been missed */
+    int last_uw;        /* How many bits since the last UW? */
+    
+};
+
+/* Init and allocate memory for a freedv-vhf framer/deframer */
+struct freedv_vhf_deframer * fvhff_create_deframer(uint8_t frame_type);
+
+/* Free the memory used by a freedv-vhf framer/deframer */
+void fvhff_destroy_deframer(struct freedv_vhf_deframer * def);
+
+/* Place codec and other bits into a frame */
+void fvhff_frame_bits(int frame_type,uint8_t bits_out[],uint8_t codec2_in[],uint8_t proto_in[],uint8_t vc_in[]);
+
+/* Find and extract frames from a stream of bits */
+int fvhff_deframe_bits(struct freedv_vhf_deframer * def,uint8_t codec2_out[],uint8_t proto_out[],uint8_t vc_out[]);
+
+/* Is the de-framer synchronized? */
+int fvhff_synchronized(struct freedv_vhf_deframer * def);
+
+#endif //_FREEDV_VHF_FRAMING_H