forked from mirrors/linux
d7e5a5462f
For the CAFÉ NAND controller, we need to support non-canonical representations of the Galois field. Allow the caller to provide its own function for generating the field, and CAFÉ can use rslib instead of its own implementation. Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org> Signed-off-by: David Woodhouse <dwmw2@infradead.org>
109 lines
3 KiB
C
109 lines
3 KiB
C
/*
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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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