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dc8f923e | 1 | // SPDX-License-Identifier: GPL-2.0 |
03ead842 | 2 | /* |
3413e189 | 3 | * Generic Reed Solomon encoder / decoder library |
03ead842 | 4 | * |
1da177e4 LT |
5 | * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de) |
6 | * | |
7 | * RS code lifted from reed solomon library written by Phil Karn | |
8 | * Copyright 2002 Phil Karn, KA9Q | |
1da177e4 | 9 | */ |
1da177e4 LT |
10 | #ifndef _RSLIB_H_ |
11 | #define _RSLIB_H_ | |
12 | ||
13 | #include <linux/list.h> | |
83a530e1 TG |
14 | #include <linux/types.h> /* for gfp_t */ |
15 | #include <linux/gfp.h> /* for GFP_KERNEL */ | |
1da177e4 | 16 | |
03ead842 | 17 | /** |
21633981 | 18 | * struct rs_codec - rs codec data |
03ead842 | 19 | * |
1da177e4 LT |
20 | * @mm: Bits per symbol |
21 | * @nn: Symbols per block (= (1<<mm)-1) | |
22 | * @alpha_to: log lookup table | |
23 | * @index_of: Antilog lookup table | |
03ead842 | 24 | * @genpoly: Generator polynomial |
1da177e4 LT |
25 | * @nroots: Number of generator roots = number of parity symbols |
26 | * @fcr: First consecutive root, index form | |
03ead842 TG |
27 | * @prim: Primitive element, index form |
28 | * @iprim: prim-th root of 1, index form | |
29 | * @gfpoly: The primitive generator polynominal | |
d7e5a546 | 30 | * @gffunc: Function to generate the field, if non-canonical representation |
03ead842 | 31 | * @users: Users of this structure |
21633981 | 32 | * @list: List entry for the rs codec list |
1da177e4 | 33 | */ |
21633981 | 34 | struct rs_codec { |
cc4b86e4 TG |
35 | int mm; |
36 | int nn; | |
1da177e4 LT |
37 | uint16_t *alpha_to; |
38 | uint16_t *index_of; | |
39 | uint16_t *genpoly; | |
cc4b86e4 TG |
40 | int nroots; |
41 | int fcr; | |
42 | int prim; | |
43 | int iprim; | |
1da177e4 | 44 | int gfpoly; |
d7e5a546 | 45 | int (*gffunc)(int); |
1da177e4 LT |
46 | int users; |
47 | struct list_head list; | |
48 | }; | |
49 | ||
21633981 TG |
50 | /** |
51 | * struct rs_control - rs control structure per instance | |
52 | * @codec: The codec used for this instance | |
45888b40 | 53 | * @buffers: Internal scratch buffers used in calls to decode_rs() |
21633981 TG |
54 | */ |
55 | struct rs_control { | |
56 | struct rs_codec *codec; | |
9dd8bb5f | 57 | uint16_t buffers[]; |
21633981 TG |
58 | }; |
59 | ||
1da177e4 LT |
60 | /* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */ |
61 | #ifdef CONFIG_REED_SOLOMON_ENC8 | |
62 | int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par, | |
63 | uint16_t invmsk); | |
64 | #endif | |
65 | #ifdef CONFIG_REED_SOLOMON_DEC8 | |
03ead842 | 66 | int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len, |
1da177e4 LT |
67 | uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, |
68 | uint16_t *corr); | |
69 | #endif | |
70 | ||
71 | /* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */ | |
72 | #ifdef CONFIG_REED_SOLOMON_ENC16 | |
73 | int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par, | |
74 | uint16_t invmsk); | |
75 | #endif | |
76 | #ifdef CONFIG_REED_SOLOMON_DEC16 | |
77 | int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len, | |
78 | uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, | |
79 | uint16_t *corr); | |
80 | #endif | |
81 | ||
83a530e1 TG |
82 | struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim, |
83 | int nroots, gfp_t gfp); | |
84 | ||
85 | /** | |
86 | * init_rs - Create a RS control struct and initialize it | |
87 | * @symsize: the symbol size (number of bits) | |
88 | * @gfpoly: the extended Galois field generator polynomial coefficients, | |
89 | * with the 0th coefficient in the low order bit. The polynomial | |
90 | * must be primitive; | |
91 | * @fcr: the first consecutive root of the rs code generator polynomial | |
92 | * in index form | |
93 | * @prim: primitive element to generate polynomial roots | |
94 | * @nroots: RS code generator polynomial degree (number of roots) | |
95 | * | |
96 | * Allocations use GFP_KERNEL. | |
97 | */ | |
98 | static inline struct rs_control *init_rs(int symsize, int gfpoly, int fcr, | |
99 | int prim, int nroots) | |
100 | { | |
101 | return init_rs_gfp(symsize, gfpoly, fcr, prim, nroots, GFP_KERNEL); | |
102 | } | |
103 | ||
d7e5a546 | 104 | struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int), |
83a530e1 | 105 | int fcr, int prim, int nroots); |
1da177e4 LT |
106 | |
107 | /* Release a rs control structure */ | |
108 | void free_rs(struct rs_control *rs); | |
109 | ||
110 | /** modulo replacement for galois field arithmetics | |
111 | * | |
21633981 | 112 | * @rs: Pointer to the RS codec |
1da177e4 LT |
113 | * @x: the value to reduce |
114 | * | |
115 | * where | |
03ead842 | 116 | * rs->mm = number of bits per symbol |
1da177e4 | 117 | * rs->nn = (2^rs->mm) - 1 |
03ead842 | 118 | * |
1da177e4 LT |
119 | * Simple arithmetic modulo would return a wrong result for values |
120 | * >= 3 * rs->nn | |
121 | */ | |
21633981 | 122 | static inline int rs_modnn(struct rs_codec *rs, int x) |
1da177e4 LT |
123 | { |
124 | while (x >= rs->nn) { | |
125 | x -= rs->nn; | |
126 | x = (x >> rs->mm) + (x & rs->nn); | |
127 | } | |
128 | return x; | |
129 | } | |
130 | ||
131 | #endif |