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105 lines
3.9 KiB
C++
105 lines
3.9 KiB
C++
/*---------------------------------------------------------------------------*\
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FILE........: freedv_vhf_framing.h
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AUTHOR......: Brady O'Brien
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DATE CREATED: 11 February 2016
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Framer and deframer for VHF FreeDV modes 'A' and 'B'
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Currently designed for-
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* 40ms ota modem frames
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* 40ms Codec2 1300 frames
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* 52 bits of Codec2 per frame
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* 16 bits of unique word per frame
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* 28 'spare' bits per frame
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* - 4 spare bits at front and end of frame (8 total) for padding
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* - 20 'protocol' bits, either for higher layers of 'protocol' or
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* - 18 'protocol' bits and 2 vericode sidechannel bits
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\*---------------------------------------------------------------------------*/
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/*
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Copyright (C) 2016 David Rowe
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All rights reserved.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License version 2.1, as
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published by the Free Software Foundation. This program is
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distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
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License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, see <http://www.gnu.org/licenses/>.
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*/
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#ifndef _FREEDV_VHF_FRAMING_H
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#define _FREEDV_VHF_FRAMING_H
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#include <cstddef>
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#include "freedv_data_channel.h"
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/* Standard frame type */
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#define FREEDV_VHF_FRAME_A 1 /* 2400A/B Frame */
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#define FREEDV_HF_FRAME_B 2 /* 800XA Frame */
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#define FREEDV_VHF_FRAME_AT 3 /* 4800T Frame */
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namespace FreeDV
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{
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struct freedv_vhf_deframer {
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int ftype; /* Type of frame to be looking for */
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int state; /* State of deframer */
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uint8_t * bits; /* Bits currently being decanted */
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uint8_t * invbits; /* Inversion of bits currently being decanted, for FMFSK */
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int bitptr; /* Pointer into circular bit buffer */
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int miss_cnt; /* How many UWs have been missed */
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int last_uw; /* How many bits since the last UW? */
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int frame_size; /* How big is a frame? */
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int uw_size; /* How big is the UW */
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int on_inv_bits; /* Are we using the inverted bits? */
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int sym_size; /* How many bits in a modem symbol */
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float ber_est; /* Bit error rate estimate */
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int total_uw_bits; /* Total RX-ed bits of UW */
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int total_uw_err; /* Total errors in UW bits */
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struct freedv_data_channel *fdc;
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};
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/* Init and allocate memory for a freedv-vhf framer/deframer */
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struct freedv_vhf_deframer * fvhff_create_deframer(uint8_t frame_type,int enable_bit_flip);
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/* Get size of various frame parameters */
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/* Frame size in bits */
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int fvhff_get_frame_size(struct freedv_vhf_deframer * def);
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/* Codec2 size in bytes */
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int fvhff_get_codec2_size(struct freedv_vhf_deframer * def);
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/* Protocol bits in bits */
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int fvhff_get_proto_size(struct freedv_vhf_deframer * def);
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/* Varicode bits in bits */
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int fvhff_get_varicode_size(struct freedv_vhf_deframer * def);
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/* Free the memory used by a freedv-vhf framer/deframer */
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void fvhff_destroy_deframer(struct freedv_vhf_deframer * def);
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/* Place codec and other bits into a frame */
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void fvhff_frame_bits(int frame_type,uint8_t bits_out[],uint8_t codec2_in[],uint8_t proto_in[],uint8_t vc_in[]);
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void fvhff_frame_data_bits(struct freedv_vhf_deframer * def, int frame_type,uint8_t bits_out[]);
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/* Find and extract frames from a stream of bits */
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int fvhff_deframe_bits(struct freedv_vhf_deframer * def,uint8_t codec2_out[],uint8_t proto_out[],uint8_t vc_out[],uint8_t bits_in[]);
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/* Is the de-framer synchronized? */
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int fvhff_synchronized(struct freedv_vhf_deframer * def);
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/* Search for a complete UW in a buffer of bits */
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std::size_t fvhff_search_uw(const uint8_t bits[],size_t nbits,
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const uint8_t uw[], std::size_t uw_len,
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std::size_t * delta_out, std::size_t bits_per_sym);
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} // FreeDV
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#endif //_FREEDV_VHF_FRAMING_H
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