1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Generic Reed Solomon encoder / decoder library
4 *
5 * Copyright 2002, Phil Karn, KA9Q
6 * May be used under the terms of the GNU General Public License (GPL)
7 *
8 * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de)
9 *
10 * Generic data width independent code which is included by the wrappers.
11 */
12 {
13 struct rs_codec *rs = rsc->codec;
14 int i, j, pad;
15 int nn = rs->nn;
16 int nroots = rs->nroots;
17 uint16_t *alpha_to = rs->alpha_to;
18 uint16_t *index_of = rs->index_of;
19 uint16_t *genpoly = rs->genpoly;
20 uint16_t fb;
21 uint16_t msk = (uint16_t) rs->nn;
22
23 /* Check length parameter for validity */
24 pad = nn - nroots - len;
25 if (pad < 0 || pad >= nn)
26 return -ERANGE;
27
28 for (i = 0; i < len; i++) {
29 fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]];
30 /* feedback term is non-zero */
31 if (fb != nn) {
32 for (j = 1; j < nroots; j++) {
33 par[j] ^= alpha_to[rs_modnn(rs, fb +
34 genpoly[nroots - j])];
35 }
36 }
37 /* Shift */
38 memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1));
39 if (fb != nn) {
40 par[nroots - 1] = alpha_to[rs_modnn(rs,
41 fb + genpoly[0])];
42 } else {
43 par[nroots - 1] = 0;
44 }
45 }
46 return 0;
47 }