diff options
Diffstat (limited to 'include/linux/rslib.h')
| -rw-r--r-- | include/linux/rslib.h | 131 |
1 files changed, 131 insertions, 0 deletions
diff --git a/include/linux/rslib.h b/include/linux/rslib.h new file mode 100644 index 000000000..238bb8524 --- /dev/null +++ b/include/linux/rslib.h @@ -0,0 +1,131 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * 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 + */ +#ifndef _RSLIB_H_ +#define _RSLIB_H_ + +#include <linux/list.h> +#include <linux/types.h> /* for gfp_t */ +#include <linux/gfp.h> /* for GFP_KERNEL */ + +/** + * struct rs_codec - rs codec data + * + * @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 codec list +*/ +struct rs_codec { + 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; +}; + +/** + * struct rs_control - rs control structure per instance + * @codec: The codec used for this instance + * @buffers: Internal scratch buffers used in calls to decode_rs() + */ +struct rs_control { + struct rs_codec *codec; + uint16_t buffers[]; +}; + +/* 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 + +struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim, + int nroots, gfp_t gfp); + +/** + * init_rs - Create a RS control struct and initialize it + * @symsize: the symbol size (number of bits) + * @gfpoly: the extended Galois field generator polynomial coefficients, + * with the 0th coefficient in the low order bit. The polynomial + * must be primitive; + * @fcr: the first consecutive root of the rs code generator polynomial + * in index form + * @prim: primitive element to generate polynomial roots + * @nroots: RS code generator polynomial degree (number of roots) + * + * Allocations use GFP_KERNEL. + */ +static inline struct rs_control *init_rs(int symsize, int gfpoly, int fcr, + int prim, int nroots) +{ + return init_rs_gfp(symsize, gfpoly, fcr, prim, nroots, GFP_KERNEL); +} + +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: Pointer to the RS codec + * @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_codec *rs, int x) +{ + while (x >= rs->nn) { + x -= rs->nn; + x = (x >> rs->mm) + (x & rs->nn); + } + return x; +} + +#endif |