1 /* 2 * include/linux/rslib.h 3 * 4 * Overview: 5 * Generic Reed Solomon encoder / decoder library 6 * 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 * 12 * $Id: rslib.h,v 1.3 2004/10/05 22:08:22 gleixner Exp $ 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 24 /** 25 * struct rs_control - rs control structure 26 * 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 31 * @genpoly: Generator polynomial 32 * @nroots: Number of generator roots = number of parity symbols 33 * @fcr: First consecutive root, index form 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 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 61 int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len, 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 */ 78 struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim, 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 90 * rs->mm = number of bits per symbol 91 * rs->nn = (2^rs->mm) - 1 92 * 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 106