Commit | Line | Data |
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03ead842 | 1 | /* |
1da177e4 LT |
2 | * include/linux/rslib.h |
3 | * | |
4 | * Overview: | |
5 | * Generic Reed Solomon encoder / decoder library | |
03ead842 | 6 | * |
1da177e4 LT |
7 | * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de) |
8 | * | |
9 | * RS code lifted from reed solomon library written by Phil Karn | |
10 | * Copyright 2002 Phil Karn, KA9Q | |
11 | * | |
03ead842 | 12 | * $Id: rslib.h,v 1.4 2005/11/07 11:14:52 gleixner Exp $ |
1da177e4 LT |
13 | * |
14 | * This program is free software; you can redistribute it and/or modify | |
15 | * it under the terms of the GNU General Public License version 2 as | |
16 | * published by the Free Software Foundation. | |
17 | */ | |
18 | ||
19 | #ifndef _RSLIB_H_ | |
20 | #define _RSLIB_H_ | |
21 | ||
22 | #include <linux/list.h> | |
23 | ||
03ead842 | 24 | /** |
1da177e4 | 25 | * struct rs_control - rs control structure |
03ead842 | 26 | * |
1da177e4 LT |
27 | * @mm: Bits per symbol |
28 | * @nn: Symbols per block (= (1<<mm)-1) | |
29 | * @alpha_to: log lookup table | |
30 | * @index_of: Antilog lookup table | |
03ead842 | 31 | * @genpoly: Generator polynomial |
1da177e4 LT |
32 | * @nroots: Number of generator roots = number of parity symbols |
33 | * @fcr: First consecutive root, index form | |
03ead842 TG |
34 | * @prim: Primitive element, index form |
35 | * @iprim: prim-th root of 1, index form | |
36 | * @gfpoly: The primitive generator polynominal | |
37 | * @users: Users of this structure | |
1da177e4 LT |
38 | * @list: List entry for the rs control list |
39 | */ | |
40 | struct rs_control { | |
41 | int mm; | |
42 | int nn; | |
43 | uint16_t *alpha_to; | |
44 | uint16_t *index_of; | |
45 | uint16_t *genpoly; | |
46 | int nroots; | |
47 | int fcr; | |
48 | int prim; | |
49 | int iprim; | |
50 | int gfpoly; | |
51 | int users; | |
52 | struct list_head list; | |
53 | }; | |
54 | ||
55 | /* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */ | |
56 | #ifdef CONFIG_REED_SOLOMON_ENC8 | |
57 | int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par, | |
58 | uint16_t invmsk); | |
59 | #endif | |
60 | #ifdef CONFIG_REED_SOLOMON_DEC8 | |
03ead842 | 61 | int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len, |
1da177e4 LT |
62 | uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, |
63 | uint16_t *corr); | |
64 | #endif | |
65 | ||
66 | /* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */ | |
67 | #ifdef CONFIG_REED_SOLOMON_ENC16 | |
68 | int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par, | |
69 | uint16_t invmsk); | |
70 | #endif | |
71 | #ifdef CONFIG_REED_SOLOMON_DEC16 | |
72 | int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len, | |
73 | uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, | |
74 | uint16_t *corr); | |
75 | #endif | |
76 | ||
77 | /* Create or get a matching rs control structure */ | |
03ead842 | 78 | struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim, |
1da177e4 LT |
79 | int nroots); |
80 | ||
81 | /* Release a rs control structure */ | |
82 | void free_rs(struct rs_control *rs); | |
83 | ||
84 | /** modulo replacement for galois field arithmetics | |
85 | * | |
86 | * @rs: the rs control structure | |
87 | * @x: the value to reduce | |
88 | * | |
89 | * where | |
03ead842 | 90 | * rs->mm = number of bits per symbol |
1da177e4 | 91 | * rs->nn = (2^rs->mm) - 1 |
03ead842 | 92 | * |
1da177e4 LT |
93 | * Simple arithmetic modulo would return a wrong result for values |
94 | * >= 3 * rs->nn | |
95 | */ | |
96 | static inline int rs_modnn(struct rs_control *rs, int x) | |
97 | { | |
98 | while (x >= rs->nn) { | |
99 | x -= rs->nn; | |
100 | x = (x >> rs->mm) + (x & rs->nn); | |
101 | } | |
102 | return x; | |
103 | } | |
104 | ||
105 | #endif |