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[/] [test_project/] [trunk/] [linux_sd_driver/] [include/] [linux/] [rslib.h] - Blame information for rev 81

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1 62 marcus.erl
/*
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 * include/linux/rslib.h
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 *
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 * Overview:
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 *   Generic Reed Solomon encoder / decoder library
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 *
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 * Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
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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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 * $Id: rslib.h,v 1.4 2005/11/07 11:14:52 gleixner Exp $
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License version 2 as
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 * published by the Free Software Foundation.
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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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/**
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 * struct rs_control - rs control structure
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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 control list
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*/
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struct rs_control {
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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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/* 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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/* Create or get a matching rs control structure */
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struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
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                           int nroots);
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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:        the rs control structure
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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_control *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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