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67 lines
1.3 KiB
67 lines
1.3 KiB
4 months ago
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/* Utility routines for FEC support
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* Copyright 2004, Phil Karn, KA9Q
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*/
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#include <stdio.h>
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#include "fec.h"
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unsigned char Partab[256];
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int P_init;
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/* Create 256-entry odd-parity lookup table
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* Needed only on non-ia32 machines
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*/
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void partab_init(void){
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int i,cnt,ti;
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/* Initialize parity lookup table */
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for(i=0;i<256;i++){
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cnt = 0;
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ti = i;
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while(ti){
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if(ti & 1)
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cnt++;
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ti >>= 1;
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}
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Partab[i] = cnt & 1;
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}
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P_init=1;
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}
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/* Lookup table giving count of 1 bits for integers 0-255 */
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int Bitcnt[] = {
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0, 1, 1, 2, 1, 2, 2, 3,
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1, 2, 2, 3, 2, 3, 3, 4,
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1, 2, 2, 3, 2, 3, 3, 4,
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2, 3, 3, 4, 3, 4, 4, 5,
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1, 2, 2, 3, 2, 3, 3, 4,
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2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5,
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3, 4, 4, 5, 4, 5, 5, 6,
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1, 2, 2, 3, 2, 3, 3, 4,
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2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5,
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3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5,
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3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6,
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4, 5, 5, 6, 5, 6, 6, 7,
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1, 2, 2, 3, 2, 3, 3, 4,
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2, 3, 3, 4, 3, 4, 4, 5,
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2, 3, 3, 4, 3, 4, 4, 5,
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3, 4, 4, 5, 4, 5, 5, 6,
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2, 3, 3, 4, 3, 4, 4, 5,
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3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6,
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4, 5, 5, 6, 5, 6, 6, 7,
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2, 3, 3, 4, 3, 4, 4, 5,
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3, 4, 4, 5, 4, 5, 5, 6,
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3, 4, 4, 5, 4, 5, 5, 6,
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4, 5, 5, 6, 5, 6, 6, 7,
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3, 4, 4, 5, 4, 5, 5, 6,
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4, 5, 5, 6, 5, 6, 6, 7,
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4, 5, 5, 6, 5, 6, 6, 7,
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5, 6, 6, 7, 6, 7, 7, 8,
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};
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