40 lines
1.0 KiB
C
40 lines
1.0 KiB
C
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/*
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This file is part of wsprd.
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File name: fano.h
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Description: Header file for sequential Fano decoder.
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Copyright 1994, Phil Karn, KA9Q
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Minor modifications by Joe Taylor, K1JT
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*/
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#ifndef FANO_H
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#define FANO_H
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int fano(unsigned int *metric, unsigned int *cycles, unsigned int *maxnp,
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unsigned char *data,unsigned char *symbols, unsigned int nbits,
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int mettab[2][256],int delta,unsigned int maxcycles);
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int encode(unsigned char *symbols,unsigned char *data,unsigned int nbytes);
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extern unsigned char Partab[];
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/* Convolutional encoder macro. Takes the encoder state, generates
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* a rate 1/2 symbol pair and stores it in 'sym'. The symbol generated from
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* POLY1 goes into the 2-bit of sym, and the symbol generated from POLY2
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* goes into the 1-bit.
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*/
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#define ENCODE(sym,encstate){\
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unsigned long _tmp;\
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\
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_tmp = (encstate) & POLY1;\
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_tmp ^= _tmp >> 16;\
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(sym) = Partab[(_tmp ^ (_tmp >> 8)) & 0xff] << 1;\
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_tmp = (encstate) & POLY2;\
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_tmp ^= _tmp >> 16;\
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(sym) |= Partab[(_tmp ^ (_tmp >> 8)) & 0xff];\
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}
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#endif
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