1 // SPDX-License-Identifier: GPL-2.0 <<
2 /* 1 /*
3 * Generic Reed Solomon encoder / decoder libr !! 2 * lib/reed_solomon/encode_rs.c
>> 3 *
>> 4 * Overview:
>> 5 * Generic Reed Solomon encoder / decoder library
4 * 6 *
5 * Copyright 2002, Phil Karn, KA9Q 7 * Copyright 2002, Phil Karn, KA9Q
6 * May be used under the terms of the GNU Gene 8 * May be used under the terms of the GNU General Public License (GPL)
7 * 9 *
8 * Adaption to the kernel by Thomas Gleixner ( 10 * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de)
9 * 11 *
10 * Generic data width independent code which i !! 12 * $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $
>> 13 *
>> 14 */
>> 15
>> 16 /* Generic data width independent code which is included by the
>> 17 * wrappers.
>> 18 * int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par)
11 */ 19 */
12 { 20 {
13 struct rs_codec *rs = rsc->codec; <<
14 int i, j, pad; 21 int i, j, pad;
15 int nn = rs->nn; 22 int nn = rs->nn;
16 int nroots = rs->nroots; 23 int nroots = rs->nroots;
17 uint16_t *alpha_to = rs->alpha_to; 24 uint16_t *alpha_to = rs->alpha_to;
18 uint16_t *index_of = rs->index_of; 25 uint16_t *index_of = rs->index_of;
19 uint16_t *genpoly = rs->genpoly; 26 uint16_t *genpoly = rs->genpoly;
20 uint16_t fb; 27 uint16_t fb;
21 uint16_t msk = (uint16_t) rs->nn; 28 uint16_t msk = (uint16_t) rs->nn;
22 29
23 /* Check length parameter for validity 30 /* Check length parameter for validity */
24 pad = nn - nroots - len; 31 pad = nn - nroots - len;
25 if (pad < 0 || pad >= nn) 32 if (pad < 0 || pad >= nn)
26 return -ERANGE; 33 return -ERANGE;
27 34
28 for (i = 0; i < len; i++) { 35 for (i = 0; i < len; i++) {
29 fb = index_of[((((uint16_t) da 36 fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]];
30 /* feedback term is non-zero * 37 /* feedback term is non-zero */
31 if (fb != nn) { 38 if (fb != nn) {
32 for (j = 1; j < nroots 39 for (j = 1; j < nroots; j++) {
33 par[j] ^= alph 40 par[j] ^= alpha_to[rs_modnn(rs, fb +
34 41 genpoly[nroots - j])];
35 } 42 }
36 } 43 }
37 /* Shift */ 44 /* Shift */
38 memmove(&par[0], &par[1], size 45 memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1));
39 if (fb != nn) { 46 if (fb != nn) {
40 par[nroots - 1] = alph 47 par[nroots - 1] = alpha_to[rs_modnn(rs,
41 48 fb + genpoly[0])];
42 } else { 49 } else {
43 par[nroots - 1] = 0; 50 par[nroots - 1] = 0;
44 } 51 }
45 } 52 }
46 return 0; 53 return 0;
47 } 54 }
48 55
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