WSJT-X/lib/wsprd/fano.h

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