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Diffstat (limited to 'kernel/include/linux/rslib.h')
| -rw-r--r-- | kernel/include/linux/rslib.h | 109 |
1 files changed, 109 insertions, 0 deletions
diff --git a/kernel/include/linux/rslib.h b/kernel/include/linux/rslib.h new file mode 100644 index 000000000..746580c19 --- /dev/null +++ b/kernel/include/linux/rslib.h @@ -0,0 +1,109 @@ +/* + * include/linux/rslib.h + * + * Overview: + * Generic Reed Solomon encoder / decoder library + * + * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de) + * + * RS code lifted from reed solomon library written by Phil Karn + * Copyright 2002 Phil Karn, KA9Q + * + * $Id: rslib.h,v 1.4 2005/11/07 11:14:52 gleixner Exp $ + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License version 2 as + * published by the Free Software Foundation. + */ + +#ifndef _RSLIB_H_ +#define _RSLIB_H_ + +#include <linux/list.h> + +/** + * struct rs_control - rs control structure + * + * @mm: Bits per symbol + * @nn: Symbols per block (= (1<<mm)-1) + * @alpha_to: log lookup table + * @index_of: Antilog lookup table + * @genpoly: Generator polynomial + * @nroots: Number of generator roots = number of parity symbols + * @fcr: First consecutive root, index form + * @prim: Primitive element, index form + * @iprim: prim-th root of 1, index form + * @gfpoly: The primitive generator polynominal + * @gffunc: Function to generate the field, if non-canonical representation + * @users: Users of this structure + * @list: List entry for the rs control list +*/ +struct rs_control { + int mm; + int nn; + uint16_t *alpha_to; + uint16_t *index_of; + uint16_t *genpoly; + int nroots; + int fcr; + int prim; + int iprim; + int gfpoly; + int (*gffunc)(int); + int users; + struct list_head list; +}; + +/* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */ +#ifdef CONFIG_REED_SOLOMON_ENC8 +int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par, + uint16_t invmsk); +#endif +#ifdef CONFIG_REED_SOLOMON_DEC8 +int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len, + uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, + uint16_t *corr); +#endif + +/* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */ +#ifdef CONFIG_REED_SOLOMON_ENC16 +int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par, + uint16_t invmsk); +#endif +#ifdef CONFIG_REED_SOLOMON_DEC16 +int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len, + uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, + uint16_t *corr); +#endif + +/* Create or get a matching rs control structure */ +struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim, + int nroots); +struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int), + int fcr, int prim, int nroots); + +/* Release a rs control structure */ +void free_rs(struct rs_control *rs); + +/** modulo replacement for galois field arithmetics + * + * @rs: the rs control structure + * @x: the value to reduce + * + * where + * rs->mm = number of bits per symbol + * rs->nn = (2^rs->mm) - 1 + * + * Simple arithmetic modulo would return a wrong result for values + * >= 3 * rs->nn +*/ +static inline int rs_modnn(struct rs_control *rs, int x) +{ + while (x >= rs->nn) { + x -= rs->nn; + x = (x >> rs->mm) + (x & rs->nn); + } + return x; +} + +#endif |