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131 lines
3.7 KiB
131 lines
3.7 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Generic Reed Solomon encoder / decoder library |
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* |
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* Copyright (C) 2004 Thomas Gleixner ([email protected]) |
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* |
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* RS code lifted from reed solomon library written by Phil Karn |
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* Copyright 2002 Phil Karn, KA9Q |
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*/ |
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#ifndef _RSLIB_H_ |
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#define _RSLIB_H_ |
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#include <linux/list.h> |
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#include <linux/types.h> /* for gfp_t */ |
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#include <linux/gfp.h> /* for GFP_KERNEL */ |
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/** |
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* struct rs_codec - rs codec data |
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* |
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* @mm: Bits per symbol |
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* @nn: Symbols per block (= (1<<mm)-1) |
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* @alpha_to: log lookup table |
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* @index_of: Antilog lookup table |
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* @genpoly: Generator polynomial |
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* @nroots: Number of generator roots = number of parity symbols |
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* @fcr: First consecutive root, index form |
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* @prim: Primitive element, index form |
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* @iprim: prim-th root of 1, index form |
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* @gfpoly: The primitive generator polynominal |
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* @gffunc: Function to generate the field, if non-canonical representation |
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* @users: Users of this structure |
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* @list: List entry for the rs codec list |
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*/ |
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struct rs_codec { |
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int mm; |
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int nn; |
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uint16_t *alpha_to; |
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uint16_t *index_of; |
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uint16_t *genpoly; |
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int nroots; |
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int fcr; |
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int prim; |
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int iprim; |
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int gfpoly; |
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int (*gffunc)(int); |
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int users; |
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struct list_head list; |
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}; |
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/** |
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* struct rs_control - rs control structure per instance |
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* @codec: The codec used for this instance |
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* @buffers: Internal scratch buffers used in calls to decode_rs() |
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*/ |
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struct rs_control { |
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struct rs_codec *codec; |
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uint16_t buffers[]; |
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}; |
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/* General purpose RS codec, 8-bit data width, symbol width 1-15 bit */ |
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#ifdef CONFIG_REED_SOLOMON_ENC8 |
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int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par, |
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uint16_t invmsk); |
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#endif |
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#ifdef CONFIG_REED_SOLOMON_DEC8 |
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int decode_rs8(struct rs_control *rs, uint8_t *data, uint16_t *par, int len, |
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uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, |
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uint16_t *corr); |
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#endif |
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/* General purpose RS codec, 16-bit data width, symbol width 1-15 bit */ |
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#ifdef CONFIG_REED_SOLOMON_ENC16 |
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int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par, |
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uint16_t invmsk); |
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#endif |
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#ifdef CONFIG_REED_SOLOMON_DEC16 |
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int decode_rs16(struct rs_control *rs, uint16_t *data, uint16_t *par, int len, |
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uint16_t *s, int no_eras, int *eras_pos, uint16_t invmsk, |
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uint16_t *corr); |
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#endif |
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struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim, |
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int nroots, gfp_t gfp); |
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/** |
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* init_rs - Create a RS control struct and initialize it |
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* @symsize: the symbol size (number of bits) |
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* @gfpoly: the extended Galois field generator polynomial coefficients, |
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* with the 0th coefficient in the low order bit. The polynomial |
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* must be primitive; |
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* @fcr: the first consecutive root of the rs code generator polynomial |
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* in index form |
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* @prim: primitive element to generate polynomial roots |
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* @nroots: RS code generator polynomial degree (number of roots) |
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* |
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* Allocations use GFP_KERNEL. |
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*/ |
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static inline struct rs_control *init_rs(int symsize, int gfpoly, int fcr, |
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int prim, int nroots) |
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{ |
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return init_rs_gfp(symsize, gfpoly, fcr, prim, nroots, GFP_KERNEL); |
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} |
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struct rs_control *init_rs_non_canonical(int symsize, int (*func)(int), |
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int fcr, int prim, int nroots); |
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/* Release a rs control structure */ |
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void free_rs(struct rs_control *rs); |
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/** modulo replacement for galois field arithmetics |
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* |
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* @rs: Pointer to the RS codec |
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* @x: the value to reduce |
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* |
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* where |
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* rs->mm = number of bits per symbol |
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* rs->nn = (2^rs->mm) - 1 |
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* |
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* Simple arithmetic modulo would return a wrong result for values |
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* >= 3 * rs->nn |
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*/ |
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static inline int rs_modnn(struct rs_codec *rs, int x) |
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{ |
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while (x >= rs->nn) { |
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x -= rs->nn; |
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x = (x >> rs->mm) + (x & rs->nn); |
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} |
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return x; |
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} |
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#endif
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