126 lines
3.5 KiB
C
126 lines
3.5 KiB
C
/*
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$Log$
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Revision 1.15 2004/06/26 03:50:14 markster
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Merge source cleanups (bug #1911)
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Revision 1.14 2003/02/12 13:59:15 matteo
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mer feb 12 14:56:57 CET 2003
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Revision 1.1.1.1 2003/02/12 13:59:15 matteo
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mer feb 12 14:56:57 CET 2003
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Revision 1.2 2000/01/05 08:20:39 markster
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Some OSS fixes and a few lpc changes to make it actually work
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* Revision 1.1 1996/08/19 22:32:07 jaf
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* Initial revision
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*
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*/
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/* -- translated by f2c (version 19951025).
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You must link the resulting object file with the libraries:
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-lf2c -lm (in that order)
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*/
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#include "f2c.h"
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#ifdef P_R_O_T_O_T_Y_P_E_S
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extern int ham84_(integer *input, integer *output, integer *errcnt);
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#endif
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/* ***************************************************************** */
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/* HAM84 Version 45G */
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/* $Log$
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* Revision 1.15 2004/06/26 03:50:14 markster
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* Merge source cleanups (bug #1911)
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*
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* Revision 1.14 2003/02/12 13:59:15 matteo
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* mer feb 12 14:56:57 CET 2003
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*
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* Revision 1.1.1.1 2003/02/12 13:59:15 matteo
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* mer feb 12 14:56:57 CET 2003
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*
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* Revision 1.2 2000/01/05 08:20:39 markster
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* Some OSS fixes and a few lpc changes to make it actually work
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*
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* Revision 1.1 1996/08/19 22:32:07 jaf
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* Initial revision
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* */
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/* Revision 1.3 1996/03/21 15:26:00 jaf */
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/* Put comment header in standard form. */
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/* Revision 1.2 1996/03/13 22:00:13 jaf */
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/* Comments added explaining that none of the local variables of this */
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/* subroutine need to be saved from one invocation to the next. */
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/* Revision 1.1 1996/02/07 14:47:04 jaf */
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/* Initial revision */
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/* ***************************************************************** */
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/* Hamming 8,4 Decoder - can correct 1 out of seven bits */
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/* and can detect up to two errors. */
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/* Input: */
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/* INPUT - Seven bit data word, 4 bits parameter and */
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/* 4 bits parity information */
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/* Input/Output: */
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/* ERRCNT - Sums errors detected by Hamming code */
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/* Output: */
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/* OUTPUT - 4 corrected parameter bits */
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/* This subroutine is entered with an eight bit word in INPUT. The 8th */
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/* bit is parity and is stripped off. The remaining 7 bits address the */
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/* hamming 8,4 table and the output OUTPUT from the table gives the 4 */
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/* bits of corrected data. If bit 4 is set, no error was detected. */
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/* ERRCNT is the number of errors counted. */
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/* This subroutine has no local state. */
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/* Subroutine */ int ham84_(integer *input, integer *output, integer *errcnt)
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{
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/* Initialized data */
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static integer dactab[128] = { 16,0,0,3,0,5,14,7,0,9,14,11,14,13,30,14,0,
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9,2,7,4,7,7,23,9,25,10,9,12,9,14,7,0,5,2,11,5,21,6,5,8,11,11,27,
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12,5,14,11,2,1,18,2,12,5,2,7,12,9,2,11,28,12,12,15,0,3,3,19,4,13,
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6,3,8,13,10,3,13,29,14,13,4,1,10,3,20,4,4,7,10,9,26,10,4,13,10,15,
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8,1,6,3,6,5,22,6,24,8,8,11,8,13,6,15,1,17,2,1,4,1,6,15,8,1,10,15,
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12,15,15,31 };
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integer i__, j, parity;
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/* Arguments */
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/* Parameters/constants */
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/* Local variables that need not be saved */
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/* Determine parity of input word */
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parity = *input & 255;
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parity ^= parity / 16;
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parity ^= parity / 4;
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parity ^= parity / 2;
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parity &= 1;
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i__ = dactab[*input & 127];
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*output = i__ & 15;
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j = i__ & 16;
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if (j != 0) {
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/* No errors detected in seven bits */
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if (parity != 0) {
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++(*errcnt);
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}
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} else {
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/* One or two errors detected */
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++(*errcnt);
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if (parity == 0) {
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/* Two errors detected */
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++(*errcnt);
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*output = -1;
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}
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}
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return 0;
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} /* ham84_ */
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