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Diffstat (limited to 'src/freedv_vhf_framing.h')
| -rw-r--r-- | src/freedv_vhf_framing.h | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/src/freedv_vhf_framing.h b/src/freedv_vhf_framing.h new file mode 100644 index 0000000..53d02d4 --- /dev/null +++ b/src/freedv_vhf_framing.h @@ -0,0 +1,99 @@ +/*---------------------------------------------------------------------------*\ + + 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 + +#include "freedv_data_channel.h" + +/* Standard frame type */ +#define FREEDV_VHF_FRAME_A 1 /* 2400A/B Frame */ +#define FREEDV_HF_FRAME_B 2 /* 800XA Frame */ +#define FREEDV_VHF_FRAME_AT 3 /* 4800T Frame */ + +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 */ + uint8_t * invbits; /* Inversion of bits currently being decanted, for FMFSK */ + + 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? */ + int frame_size; /* How big is a frame? */ + int uw_size; /* How big is the UW */ + int on_inv_bits; /* Are we using the inverted bits? */ + int sym_size; /* How many bits in a modem symbol */ + + float ber_est; /* Bit error rate estimate */ + int total_uw_bits; /* Total RX-ed bits of UW */ + int total_uw_err; /* Total errors in UW bits */ + + struct freedv_data_channel *fdc; +}; + +/* Init and allocate memory for a freedv-vhf framer/deframer */ +struct freedv_vhf_deframer * fvhff_create_deframer(uint8_t frame_type,int enable_bit_flip); + +/* Get size of various frame parameters */ +/* Frame size in bits */ +int fvhff_get_frame_size(struct freedv_vhf_deframer * def); +/* Codec2 size in bytes */ +int fvhff_get_codec2_size(struct freedv_vhf_deframer * def); +/* Protocol bits in bits */ +int fvhff_get_proto_size(struct freedv_vhf_deframer * def); +/* Varicode bits in bits */ +int fvhff_get_varicode_size(struct freedv_vhf_deframer * def); + +/* 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[]); +void fvhff_frame_data_bits(struct freedv_vhf_deframer * def, int frame_type,uint8_t bits_out[]); + +/* 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[],uint8_t bits_in[]); + +/* Is the de-framer synchronized? */ +int fvhff_synchronized(struct freedv_vhf_deframer * def); + +/* Search for a complete UW in a buffer of bits */ +size_t fvhff_search_uw(const uint8_t bits[],size_t nbits, + const uint8_t uw[], size_t uw_len, + size_t * delta_out, size_t bits_per_sym); + +#endif //_FREEDV_VHF_FRAMING_H |