| // 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 |