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Release 4.12 include/linux/rslib.h

Directory: include/linux
 * include/linux/rslib.h
 * Overview:
 *   Generic Reed Solomon encoder / decoder library
 * Copyright (C) 2004 Thomas Gleixner (
 * RS code lifted from reed solomon library written by Phil Karn
 * Copyright 2002 Phil Karn, KA9Q
 * $Id: rslib.h,v 1.4 2005/11/07 11:14:52 gleixner Exp $
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.

#ifndef _RSLIB_H_

#define _RSLIB_H_

#include <linux/list.h>

 * struct rs_control - rs control structure
 * @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 control list

struct rs_control {
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;

/* General purpose RS codec, 8-bit data width, symbol width 1-15 bit  */
int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
	       uint16_t invmsk);
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);

/* General purpose RS codec, 16-bit data width, symbol width 1-15 bit  */
int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par,
		uint16_t invmsk);
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);

/* Create or get a matching rs control structure */
struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
			   int nroots);
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:        the rs control structure
 *  @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_control *rs, int x) { while (x >= rs->nn) { x -= rs->nn; x = (x >> rs->mm) + (x & rs->nn); } return x; }


Thomas Gleixner52100.00%1100.00%


Overall Contributors

Thomas Gleixner28688.54%266.67%
Segher Boessenkool3711.46%133.33%
Directory: include/linux
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