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lib/reed_solomon/encode_rs.c
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/*
* lib/reed_solomon/encode_rs.c
*
* Overview:
* Generic Reed Solomon encoder / decoder library
*
* Copyright 2002, Phil Karn, KA9Q
* May be used under the terms of the GNU General Public License (GPL)
*
* Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de)
*
* $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $
*
*/
/* Generic data width independent code which is included by the
* wrappers.
* int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par)
*/
{
int i, j, pad;
int nn = rs->nn;
int nroots = rs->nroots;
uint16_t *alpha_to = rs->alpha_to;
uint16_t *index_of = rs->index_of;
uint16_t *genpoly = rs->genpoly;
uint16_t fb;
uint16_t msk = (uint16_t) rs->nn;
/* Check length parameter for validity */
pad = nn - nroots - len;
if (pad < 0 || pad >= nn)
return -ERANGE;
for (i = 0; i < len; i++) {
fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]];
/* feedback term is non-zero */
if (fb != nn) {
for (j = 1; j < nroots; j++) {
par[j] ^= alpha_to[rs_modnn(rs, fb +
genpoly[nroots - j])];
}
}
/* Shift */
memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1));
if (fb != nn) {
par[nroots - 1] = alpha_to[rs_modnn(rs,
fb + genpoly[0])];
} else {
par[nroots - 1] = 0;
}
}
return 0;
}
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