// 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/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.
*/ staticinlinestruct 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
*/ staticinlineint 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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