Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
This commit is contained in:
Linus Torvalds
335
lib/reed_solomon/reed_solomon.c
Normal file
335
lib/reed_solomon/reed_solomon.c
Normal file
@@ -0,0 +1,335 @@
|
||||
/*
|
||||
* lib/reed_solomon/rslib.c
|
||||
*
|
||||
* Overview:
|
||||
* Generic Reed Solomon encoder / decoder library
|
||||
*
|
||||
* Copyright (C) 2004 Thomas Gleixner (tglx@linutronix.de)
|
||||
*
|
||||
* Reed Solomon code lifted from reed solomon library written by Phil Karn
|
||||
* Copyright 2002 Phil Karn, KA9Q
|
||||
*
|
||||
* $Id: rslib.c,v 1.5 2004/10/22 15:41:47 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.
|
||||
*
|
||||
* Description:
|
||||
*
|
||||
* The generic Reed Solomon library provides runtime configurable
|
||||
* encoding / decoding of RS codes.
|
||||
* Each user must call init_rs to get a pointer to a rs_control
|
||||
* structure for the given rs parameters. This structure is either
|
||||
* generated or a already available matching control structure is used.
|
||||
* If a structure is generated then the polynomial arrays for
|
||||
* fast encoding / decoding are built. This can take some time so
|
||||
* make sure not to call this function from a time critical path.
|
||||
* Usually a module / driver should initialize the necessary
|
||||
* rs_control structure on module / driver init and release it
|
||||
* on exit.
|
||||
* The encoding puts the calculated syndrome into a given syndrome
|
||||
* buffer.
|
||||
* The decoding is a two step process. The first step calculates
|
||||
* the syndrome over the received (data + syndrome) and calls the
|
||||
* second stage, which does the decoding / error correction itself.
|
||||
* Many hw encoders provide a syndrome calculation over the received
|
||||
* data + syndrome and can call the second stage directly.
|
||||
*
|
||||
*/
|
||||
|
||||
#include <linux/errno.h>
|
||||
#include <linux/kernel.h>
|
||||
#include <linux/init.h>
|
||||
#include <linux/module.h>
|
||||
#include <linux/rslib.h>
|
||||
#include <linux/slab.h>
|
||||
#include <asm/semaphore.h>
|
||||
|
||||
/* This list holds all currently allocated rs control structures */
|
||||
static LIST_HEAD (rslist);
|
||||
/* Protection for the list */
|
||||
static DECLARE_MUTEX(rslistlock);
|
||||
|
||||
/**
|
||||
* rs_init - Initialize a Reed-Solomon codec
|
||||
*
|
||||
* @symsize: symbol size, bits (1-8)
|
||||
* @gfpoly: Field generator polynomial coefficients
|
||||
* @fcr: first root of RS code generator polynomial, index form
|
||||
* @prim: primitive element to generate polynomial roots
|
||||
* @nroots: RS code generator polynomial degree (number of roots)
|
||||
*
|
||||
* Allocate a control structure and the polynom arrays for faster
|
||||
* en/decoding. Fill the arrays according to the given parameters
|
||||
*/
|
||||
static struct rs_control *rs_init(int symsize, int gfpoly, int fcr,
|
||||
int prim, int nroots)
|
||||
{
|
||||
struct rs_control *rs;
|
||||
int i, j, sr, root, iprim;
|
||||
|
||||
/* Allocate the control structure */
|
||||
rs = kmalloc(sizeof (struct rs_control), GFP_KERNEL);
|
||||
if (rs == NULL)
|
||||
return NULL;
|
||||
|
||||
INIT_LIST_HEAD(&rs->list);
|
||||
|
||||
rs->mm = symsize;
|
||||
rs->nn = (1 << symsize) - 1;
|
||||
rs->fcr = fcr;
|
||||
rs->prim = prim;
|
||||
rs->nroots = nroots;
|
||||
rs->gfpoly = gfpoly;
|
||||
|
||||
/* Allocate the arrays */
|
||||
rs->alpha_to = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
|
||||
if (rs->alpha_to == NULL)
|
||||
goto errrs;
|
||||
|
||||
rs->index_of = kmalloc(sizeof(uint16_t) * (rs->nn + 1), GFP_KERNEL);
|
||||
if (rs->index_of == NULL)
|
||||
goto erralp;
|
||||
|
||||
rs->genpoly = kmalloc(sizeof(uint16_t) * (rs->nroots + 1), GFP_KERNEL);
|
||||
if(rs->genpoly == NULL)
|
||||
goto erridx;
|
||||
|
||||
/* Generate Galois field lookup tables */
|
||||
rs->index_of[0] = rs->nn; /* log(zero) = -inf */
|
||||
rs->alpha_to[rs->nn] = 0; /* alpha**-inf = 0 */
|
||||
sr = 1;
|
||||
for (i = 0; i < rs->nn; i++) {
|
||||
rs->index_of[sr] = i;
|
||||
rs->alpha_to[i] = sr;
|
||||
sr <<= 1;
|
||||
if (sr & (1 << symsize))
|
||||
sr ^= gfpoly;
|
||||
sr &= rs->nn;
|
||||
}
|
||||
/* If it's not primitive, exit */
|
||||
if(sr != 1)
|
||||
goto errpol;
|
||||
|
||||
/* Find prim-th root of 1, used in decoding */
|
||||
for(iprim = 1; (iprim % prim) != 0; iprim += rs->nn);
|
||||
/* prim-th root of 1, index form */
|
||||
rs->iprim = iprim / prim;
|
||||
|
||||
/* Form RS code generator polynomial from its roots */
|
||||
rs->genpoly[0] = 1;
|
||||
for (i = 0, root = fcr * prim; i < nroots; i++, root += prim) {
|
||||
rs->genpoly[i + 1] = 1;
|
||||
/* Multiply rs->genpoly[] by @**(root + x) */
|
||||
for (j = i; j > 0; j--) {
|
||||
if (rs->genpoly[j] != 0) {
|
||||
rs->genpoly[j] = rs->genpoly[j -1] ^
|
||||
rs->alpha_to[rs_modnn(rs,
|
||||
rs->index_of[rs->genpoly[j]] + root)];
|
||||
} else
|
||||
rs->genpoly[j] = rs->genpoly[j - 1];
|
||||
}
|
||||
/* rs->genpoly[0] can never be zero */
|
||||
rs->genpoly[0] =
|
||||
rs->alpha_to[rs_modnn(rs,
|
||||
rs->index_of[rs->genpoly[0]] + root)];
|
||||
}
|
||||
/* convert rs->genpoly[] to index form for quicker encoding */
|
||||
for (i = 0; i <= nroots; i++)
|
||||
rs->genpoly[i] = rs->index_of[rs->genpoly[i]];
|
||||
return rs;
|
||||
|
||||
/* Error exit */
|
||||
errpol:
|
||||
kfree(rs->genpoly);
|
||||
erridx:
|
||||
kfree(rs->index_of);
|
||||
erralp:
|
||||
kfree(rs->alpha_to);
|
||||
errrs:
|
||||
kfree(rs);
|
||||
return NULL;
|
||||
}
|
||||
|
||||
|
||||
/**
|
||||
* free_rs - Free the rs control structure, if its not longer used
|
||||
*
|
||||
* @rs: the control structure which is not longer used by the
|
||||
* caller
|
||||
*/
|
||||
void free_rs(struct rs_control *rs)
|
||||
{
|
||||
down(&rslistlock);
|
||||
rs->users--;
|
||||
if(!rs->users) {
|
||||
list_del(&rs->list);
|
||||
kfree(rs->alpha_to);
|
||||
kfree(rs->index_of);
|
||||
kfree(rs->genpoly);
|
||||
kfree(rs);
|
||||
}
|
||||
up(&rslistlock);
|
||||
}
|
||||
|
||||
/**
|
||||
* init_rs - Find a matching or allocate a new rs control structure
|
||||
*
|
||||
* @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)
|
||||
*/
|
||||
struct rs_control *init_rs(int symsize, int gfpoly, int fcr, int prim,
|
||||
int nroots)
|
||||
{
|
||||
struct list_head *tmp;
|
||||
struct rs_control *rs;
|
||||
|
||||
/* Sanity checks */
|
||||
if (symsize < 1)
|
||||
return NULL;
|
||||
if (fcr < 0 || fcr >= (1<<symsize))
|
||||
return NULL;
|
||||
if (prim <= 0 || prim >= (1<<symsize))
|
||||
return NULL;
|
||||
if (nroots < 0 || nroots >= (1<<symsize) || nroots > 8)
|
||||
return NULL;
|
||||
|
||||
down(&rslistlock);
|
||||
|
||||
/* Walk through the list and look for a matching entry */
|
||||
list_for_each(tmp, &rslist) {
|
||||
rs = list_entry(tmp, struct rs_control, list);
|
||||
if (symsize != rs->mm)
|
||||
continue;
|
||||
if (gfpoly != rs->gfpoly)
|
||||
continue;
|
||||
if (fcr != rs->fcr)
|
||||
continue;
|
||||
if (prim != rs->prim)
|
||||
continue;
|
||||
if (nroots != rs->nroots)
|
||||
continue;
|
||||
/* We have a matching one already */
|
||||
rs->users++;
|
||||
goto out;
|
||||
}
|
||||
|
||||
/* Create a new one */
|
||||
rs = rs_init(symsize, gfpoly, fcr, prim, nroots);
|
||||
if (rs) {
|
||||
rs->users = 1;
|
||||
list_add(&rs->list, &rslist);
|
||||
}
|
||||
out:
|
||||
up(&rslistlock);
|
||||
return rs;
|
||||
}
|
||||
|
||||
#ifdef CONFIG_REED_SOLOMON_ENC8
|
||||
/**
|
||||
* encode_rs8 - Calculate the parity for data values (8bit data width)
|
||||
*
|
||||
* @rs: the rs control structure
|
||||
* @data: data field of a given type
|
||||
* @len: data length
|
||||
* @par: parity data, must be initialized by caller (usually all 0)
|
||||
* @invmsk: invert data mask (will be xored on data)
|
||||
*
|
||||
* The parity uses a uint16_t data type to enable
|
||||
* symbol size > 8. The calling code must take care of encoding of the
|
||||
* syndrome result for storage itself.
|
||||
*/
|
||||
int encode_rs8(struct rs_control *rs, uint8_t *data, int len, uint16_t *par,
|
||||
uint16_t invmsk)
|
||||
{
|
||||
#include "encode_rs.c"
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(encode_rs8);
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_REED_SOLOMON_DEC8
|
||||
/**
|
||||
* decode_rs8 - Decode codeword (8bit data width)
|
||||
*
|
||||
* @rs: the rs control structure
|
||||
* @data: data field of a given type
|
||||
* @par: received parity data field
|
||||
* @len: data length
|
||||
* @s: syndrome data field (if NULL, syndrome is calculated)
|
||||
* @no_eras: number of erasures
|
||||
* @eras_pos: position of erasures, can be NULL
|
||||
* @invmsk: invert data mask (will be xored on data, not on parity!)
|
||||
* @corr: buffer to store correction bitmask on eras_pos
|
||||
*
|
||||
* The syndrome and parity uses a uint16_t data type to enable
|
||||
* symbol size > 8. The calling code must take care of decoding of the
|
||||
* syndrome result and the received parity before calling this code.
|
||||
*/
|
||||
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)
|
||||
{
|
||||
#include "decode_rs.c"
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(decode_rs8);
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_REED_SOLOMON_ENC16
|
||||
/**
|
||||
* encode_rs16 - Calculate the parity for data values (16bit data width)
|
||||
*
|
||||
* @rs: the rs control structure
|
||||
* @data: data field of a given type
|
||||
* @len: data length
|
||||
* @par: parity data, must be initialized by caller (usually all 0)
|
||||
* @invmsk: invert data mask (will be xored on data, not on parity!)
|
||||
*
|
||||
* Each field in the data array contains up to symbol size bits of valid data.
|
||||
*/
|
||||
int encode_rs16(struct rs_control *rs, uint16_t *data, int len, uint16_t *par,
|
||||
uint16_t invmsk)
|
||||
{
|
||||
#include "encode_rs.c"
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(encode_rs16);
|
||||
#endif
|
||||
|
||||
#ifdef CONFIG_REED_SOLOMON_DEC16
|
||||
/**
|
||||
* decode_rs16 - Decode codeword (16bit data width)
|
||||
*
|
||||
* @rs: the rs control structure
|
||||
* @data: data field of a given type
|
||||
* @par: received parity data field
|
||||
* @len: data length
|
||||
* @s: syndrome data field (if NULL, syndrome is calculated)
|
||||
* @no_eras: number of erasures
|
||||
* @eras_pos: position of erasures, can be NULL
|
||||
* @invmsk: invert data mask (will be xored on data, not on parity!)
|
||||
* @corr: buffer to store correction bitmask on eras_pos
|
||||
*
|
||||
* Each field in the data array contains up to symbol size bits of valid data.
|
||||
*/
|
||||
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)
|
||||
{
|
||||
#include "decode_rs.c"
|
||||
}
|
||||
EXPORT_SYMBOL_GPL(decode_rs16);
|
||||
#endif
|
||||
|
||||
EXPORT_SYMBOL_GPL(init_rs);
|
||||
EXPORT_SYMBOL_GPL(free_rs);
|
||||
|
||||
MODULE_LICENSE("GPL");
|
||||
MODULE_DESCRIPTION("Reed Solomon encoder/decoder");
|
||||
MODULE_AUTHOR("Phil Karn, Thomas Gleixner");
|
||||
|
||||
Reference in New Issue
Block a user