1 /* 2 * include/linux/rslib.h 3 * 4 * Overview: 5 * Generic Reed Solomon encoder / decoder library 6 * 7 * Copyright (C) 2004 Thomas Gleixner ([email protected]) 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 #include <linux/types.h> /* for gfp_t */ 24 #include <linux/gfp.h> /* for GFP_KERNEL */ 25 26 /** 27 * struct rs_control - rs control structure 28 * 29 * @mm: Bits per symbol 30 * @nn: Symbols per block (= (1<<mm)-1) 31 * @alpha_to: log lookup table 32 * @index_of: Antilog lookup table 33 * @genpoly: Generator polynomial 34 * @nroots: Number of generator roots = number of parity symbols 35 * @fcr: First consecutive root, index form 36 * @prim: Primitive element, index form 37 * @iprim: prim-th root of 1, index form 38 * @gfpoly: The primitive generator polynominal 39 * @gffunc: Function to generate the field, if non-canonical representation 40 * @users: Users of this structure 41 * @list: List entry for the rs control list 42 */ 43 struct rs_control { 44 int mm; 45 int nn; 46 uint16_t *alpha_to; 47 uint16_t *index_of; 48 uint16_t *genpoly; 49 int nroots; 50 int fcr; 51 int prim; 52 int iprim; 53 int gfpoly; 54 int (*gffunc)(int); 55 int users; 56 struct list_head list; 57 }; 58 59 /* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */ 60 #ifdef CONFIG_REED_SOLOMON_ENC8 61 int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par, 62 uint16_t invmsk); 63 #endif 64 #ifdef CONFIG_REED_SOLOMON_DEC8 65 int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len, 66 uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, 67 uint16_t *corr); 68 #endif 69 70 /* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */ 71 #ifdef CONFIG_REED_SOLOMON_ENC16 72 int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par, 73 uint16_t invmsk); 74 #endif 75 #ifdef CONFIG_REED_SOLOMON_DEC16 76 int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len, 77 uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, 78 uint16_t *corr); 79 #endif 80 81 /* Create or get a matching rs control structure */ 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 } 103 104 struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int), 105 int fcr, int prim, int nroots); 106 107 /* Release a rs control structure */ 108 void free_rs(struct rs_control *rs); 109 110 /** modulo replacement for galois field arithmetics 111 * 112 * @rs: the rs control structure 113 * @x: the value to reduce 114 * 115 * where 116 * rs->mm = number of bits per symbol 117 * rs->nn = (2^rs->mm) - 1 118 * 119 * Simple arithmetic modulo would return a wrong result for values 120 * >= 3 * rs->nn 121 */ 122 static inline int rs_modnn(struct rs_control *rs, int x) 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 132