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55 lines
1.3 KiB
55 lines
1.3 KiB
20 years ago
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/*
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* lib/reed_solomon/encode_rs.c
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*
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* Overview:
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* Generic Reed Solomon encoder / decoder library
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*
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* Copyright 2002, Phil Karn, KA9Q
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* May be used under the terms of the GNU General Public License (GPL)
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*
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* Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de)
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*
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* $Id: encode_rs.c,v 1.4 2004/10/22 15:41:47 gleixner Exp $
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*
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*/
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/* Generic data width independent code which is included by the
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* wrappers.
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* int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par)
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*/
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{
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int i, j, pad;
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int nn = rs->nn;
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int nroots = rs->nroots;
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uint16_t *alpha_to = rs->alpha_to;
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uint16_t *index_of = rs->index_of;
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uint16_t *genpoly = rs->genpoly;
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uint16_t fb;
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uint16_t msk = (uint16_t) rs->nn;
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/* Check length parameter for validity */
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pad = nn - nroots - len;
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if (pad < 0 || pad >= nn)
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return -ERANGE;
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for (i = 0; i < len; i++) {
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fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]];
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/* feedback term is non-zero */
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if (fb != nn) {
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for (j = 1; j < nroots; j++) {
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par[j] ^= alpha_to[rs_modnn(rs, fb +
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genpoly[nroots - j])];
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}
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}
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/* Shift */
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memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1));
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if (fb != nn) {
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par[nroots - 1] = alpha_to[rs_modnn(rs,
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fb + genpoly[0])];
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} else {
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par[nroots - 1] = 0;
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}
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}
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return 0;
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}
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