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 1.4 2005/11/07 11:14:52 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 * @gffunc: Function to generate the field, if non-canonical representation 38 * @users: Users of this structure 39 * @list: List entry for the rs control list 40*/ 41struct rs_control { 42 int mm; 43 int nn; 44 uint16_t *alpha_to; 45 uint16_t *index_of; 46 uint16_t *genpoly; 47 int nroots; 48 int fcr; 49 int prim; 50 int iprim; 51 int gfpoly; 52 int (*gffunc)(int); 53 int users; 54 struct list_head list; 55}; 56 57/* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */ 58#ifdef CONFIG_REED_SOLOMON_ENC8 59int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par, 60 uint16_t invmsk); 61#endif 62#ifdef CONFIG_REED_SOLOMON_DEC8 63int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len, 64 uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, 65 uint16_t *corr); 66#endif 67 68/* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */ 69#ifdef CONFIG_REED_SOLOMON_ENC16 70int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par, 71 uint16_t invmsk); 72#endif 73#ifdef CONFIG_REED_SOLOMON_DEC16 74int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len, 75 uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, 76 uint16_t *corr); 77#endif 78 79/* Create or get a matching rs control structure */ 80struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim, 81 int nroots); 82struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int), 83 int fcr, int prim, int nroots); 84 85/* Release a rs control structure */ 86void free_rs(struct rs_control *rs); 87 88/** modulo replacement for galois field arithmetics 89 * 90 * @rs: the rs control structure 91 * @x: the value to reduce 92 * 93 * where 94 * rs->mm = number of bits per symbol 95 * rs->nn = (2^rs->mm) - 1 96 * 97 * Simple arithmetic modulo would return a wrong result for values 98 * >= 3 * rs->nn 99*/ 100static inline int rs_modnn(struct rs_control *rs, int x) 101{ 102 while (x >= rs->nn) { 103 x -= rs->nn; 104 x = (x >> rs->mm) + (x & rs->nn); 105 } 106 return x; 107} 108 109#endif 110