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Add software for Golay(24,12) lookup table.

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git-svn-id: svn+ssh://svn.code.sf.net/p/wsjt/wsjt/branches/wsjtx@6414 ab8295b8-cf94-4d9e-aec4-7959e3be5d79
This commit is contained in:
Joe Taylor 2016-01-21 18:01:31 +00:00
parent eecf44782c
commit dc0ed894f6
1 changed files with 28 additions and 0 deletions
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lib/golay24_table.c Normal file
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void golay24_table_(int cw[])
{
// Compute arnd return the table of 4096 codewords for the Golay (24,12) code.
// Array y contains the twelve rows (columns) of the parity-check matrix
int y[12] = { 0x7ff, 0xee2, 0xdc5, 0xb8b, 0xf16, 0xe2d,
0xc5b, 0x8b7, 0x96e, 0xadc, 0xdb8, 0xb71 };
int c[2]; /* Codeword composed of 12-bit info and 12-bit parity */
int i,j,k;
int aux;
int weight(int vector);
for(k=0; k<4096; k++) {
c[0] = k;
c[1] = 0;
for (i=0; i<12; i++) {
aux = 0;
for (j=0; j<12; j++) {
aux = aux ^ ((c[0] & y[i]) >> j & 1);
}
c[1] = (c[1] << 1) ^ aux;
}
cw[k]=4096*c[0] + c[1];
}
}