/*
* include/linux/rslib.h
*
* Overview:
* 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
*
* $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 */
#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

/* 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;
}

#endif