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- // SPDX-License-Identifier: GPL-2.0
- /*
- * Generic Reed Solomon encoder / decoder library
- *
- * Copyright (C) 2004 Thomas Gleixner ([email protected])
- *
- * 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
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