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03ead842 | 1 | /* |
1da177e4 LT |
2 | * lib/reed_solomon/encode_rs.c |
3 | * | |
4 | * Overview: | |
5 | * Generic Reed Solomon encoder / decoder library | |
03ead842 | 6 | * |
1da177e4 LT |
7 | * Copyright 2002, Phil Karn, KA9Q |
8 | * May be used under the terms of the GNU General Public License (GPL) | |
9 | * | |
10 | * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de) | |
11 | * | |
03ead842 | 12 | * $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $ |
1da177e4 LT |
13 | * |
14 | */ | |
15 | ||
03ead842 | 16 | /* Generic data width independent code which is included by the |
1da177e4 LT |
17 | * wrappers. |
18 | * int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par) | |
19 | */ | |
20 | { | |
21 | int i, j, pad; | |
22 | int nn = rs->nn; | |
23 | int nroots = rs->nroots; | |
24 | uint16_t *alpha_to = rs->alpha_to; | |
25 | uint16_t *index_of = rs->index_of; | |
26 | uint16_t *genpoly = rs->genpoly; | |
27 | uint16_t fb; | |
28 | uint16_t msk = (uint16_t) rs->nn; | |
29 | ||
30 | /* Check length parameter for validity */ | |
31 | pad = nn - nroots - len; | |
32 | if (pad < 0 || pad >= nn) | |
33 | return -ERANGE; | |
34 | ||
35 | for (i = 0; i < len; i++) { | |
36 | fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]]; | |
37 | /* feedback term is non-zero */ | |
03ead842 | 38 | if (fb != nn) { |
1da177e4 | 39 | for (j = 1; j < nroots; j++) { |
03ead842 | 40 | par[j] ^= alpha_to[rs_modnn(rs, fb + |
1da177e4 LT |
41 | genpoly[nroots - j])]; |
42 | } | |
43 | } | |
44 | /* Shift */ | |
45 | memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1)); | |
46 | if (fb != nn) { | |
03ead842 | 47 | par[nroots - 1] = alpha_to[rs_modnn(rs, |
1da177e4 LT |
48 | fb + genpoly[0])]; |
49 | } else { | |
50 | par[nroots - 1] = 0; | |
51 | } | |
52 | } | |
53 | return 0; | |
54 | } |