forked from Minki/linux
55 lines
1.3 KiB
C
55 lines
1.3 KiB
C
|
/*
|
||
|
|
* 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 1.4 2004/10/22 15:41:47 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;
|
||
|
|
}
|