Commit | Line | Data |
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03ead842 | 1 | /* |
3413e189 | 2 | * Generic Reed Solomon encoder / decoder library |
03ead842 | 3 | * |
1da177e4 LT |
4 | * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de) |
5 | * | |
6 | * RS code lifted from reed solomon library written by Phil Karn | |
7 | * Copyright 2002 Phil Karn, KA9Q | |
8 | * | |
1da177e4 LT |
9 | * This program is free software; you can redistribute it and/or modify |
10 | * it under the terms of the GNU General Public License version 2 as | |
11 | * published by the Free Software Foundation. | |
12 | */ | |
13 | ||
14 | #ifndef _RSLIB_H_ | |
15 | #define _RSLIB_H_ | |
16 | ||
17 | #include <linux/list.h> | |
83a530e1 TG |
18 | #include <linux/types.h> /* for gfp_t */ |
19 | #include <linux/gfp.h> /* for GFP_KERNEL */ | |
1da177e4 | 20 | |
03ead842 | 21 | /** |
1da177e4 | 22 | * struct rs_control - rs control structure |
03ead842 | 23 | * |
1da177e4 LT |
24 | * @mm: Bits per symbol |
25 | * @nn: Symbols per block (= (1<<mm)-1) | |
26 | * @alpha_to: log lookup table | |
27 | * @index_of: Antilog lookup table | |
03ead842 | 28 | * @genpoly: Generator polynomial |
1da177e4 LT |
29 | * @nroots: Number of generator roots = number of parity symbols |
30 | * @fcr: First consecutive root, index form | |
03ead842 TG |
31 | * @prim: Primitive element, index form |
32 | * @iprim: prim-th root of 1, index form | |
33 | * @gfpoly: The primitive generator polynominal | |
d7e5a546 | 34 | * @gffunc: Function to generate the field, if non-canonical representation |
03ead842 | 35 | * @users: Users of this structure |
1da177e4 LT |
36 | * @list: List entry for the rs control list |
37 | */ | |
38 | struct rs_control { | |
cc4b86e4 TG |
39 | int mm; |
40 | int nn; | |
1da177e4 LT |
41 | uint16_t *alpha_to; |
42 | uint16_t *index_of; | |
43 | uint16_t *genpoly; | |
cc4b86e4 TG |
44 | int nroots; |
45 | int fcr; | |
46 | int prim; | |
47 | int iprim; | |
1da177e4 | 48 | int gfpoly; |
d7e5a546 | 49 | int (*gffunc)(int); |
1da177e4 LT |
50 | int users; |
51 | struct list_head list; | |
52 | }; | |
53 | ||
54 | /* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */ | |
55 | #ifdef CONFIG_REED_SOLOMON_ENC8 | |
56 | int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par, | |
57 | uint16_t invmsk); | |
58 | #endif | |
59 | #ifdef CONFIG_REED_SOLOMON_DEC8 | |
03ead842 | 60 | int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len, |
1da177e4 LT |
61 | uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, |
62 | uint16_t *corr); | |
63 | #endif | |
64 | ||
65 | /* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */ | |
66 | #ifdef CONFIG_REED_SOLOMON_ENC16 | |
67 | int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par, | |
68 | uint16_t invmsk); | |
69 | #endif | |
70 | #ifdef CONFIG_REED_SOLOMON_DEC16 | |
71 | int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len, | |
72 | uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, | |
73 | uint16_t *corr); | |
74 | #endif | |
75 | ||
76 | /* Create or get a matching rs control structure */ | |
83a530e1 TG |
77 | struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim, |
78 | int nroots, gfp_t gfp); | |
79 | ||
80 | /** | |
81 | * init_rs - Create a RS control struct and initialize it | |
82 | * @symsize: the symbol size (number of bits) | |
83 | * @gfpoly: the extended Galois field generator polynomial coefficients, | |
84 | * with the 0th coefficient in the low order bit. The polynomial | |
85 | * must be primitive; | |
86 | * @fcr: the first consecutive root of the rs code generator polynomial | |
87 | * in index form | |
88 | * @prim: primitive element to generate polynomial roots | |
89 | * @nroots: RS code generator polynomial degree (number of roots) | |
90 | * | |
91 | * Allocations use GFP_KERNEL. | |
92 | */ | |
93 | static inline struct rs_control *init_rs(int symsize, int gfpoly, int fcr, | |
94 | int prim, int nroots) | |
95 | { | |
96 | return init_rs_gfp(symsize, gfpoly, fcr, prim, nroots, GFP_KERNEL); | |
97 | } | |
98 | ||
d7e5a546 | 99 | struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int), |
83a530e1 | 100 | int fcr, int prim, int nroots); |
1da177e4 LT |
101 | |
102 | /* Release a rs control structure */ | |
103 | void free_rs(struct rs_control *rs); | |
104 | ||
105 | /** modulo replacement for galois field arithmetics | |
106 | * | |
107 | * @rs: the rs control structure | |
108 | * @x: the value to reduce | |
109 | * | |
110 | * where | |
03ead842 | 111 | * rs->mm = number of bits per symbol |
1da177e4 | 112 | * rs->nn = (2^rs->mm) - 1 |
03ead842 | 113 | * |
1da177e4 LT |
114 | * Simple arithmetic modulo would return a wrong result for values |
115 | * >= 3 * rs->nn | |
116 | */ | |
117 | static inline int rs_modnn(struct rs_control *rs, int x) | |
118 | { | |
119 | while (x >= rs->nn) { | |
120 | x -= rs->nn; | |
121 | x = (x >> rs->mm) + (x & rs->nn); | |
122 | } | |
123 | return x; | |
124 | } | |
125 | ||
126 | #endif |