lib/reed_solomon/reed_solomon.c - kernel/common - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Generic Reed Solomon encoder / decoder library
  *
  * Copyright (C) 2004 Thomas Gleixner ([email protected])
  *
  * Reed Solomon code lifted from reed solomon library written by Phil Karn
  * Copyright 2002 Phil Karn, KA9Q
  *
  * 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. The control struct is unique per instance.
  * It points to a codec which can be shared by multiple control structures.
  * If a codec is newly allocated 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 <linux/mutex.h>

 enum {
 	RS_DECODE_LAMBDA,
 	RS_DECODE_SYN,
 	RS_DECODE_B,
 	RS_DECODE_T,
 	RS_DECODE_OMEGA,
 	RS_DECODE_ROOT,
 	RS_DECODE_REG,
 	RS_DECODE_LOC,
 	RS_DECODE_NUM_BUFFERS
 };

 /* This list holds all currently allocated rs codec structures */
 static LIST_HEAD(codec_list);
 /* Protection for the list */
 static DEFINE_MUTEX(rslistlock);

 /**
  * codec_init - Initialize a Reed-Solomon codec
  * @symsize:	symbol size, bits (1-8)
  * @gfpoly:	Field generator polynomial coefficients
  * @gffunc:	Field generator function
  * @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)
  * @gfp:	GFP_ flags for allocations
  *
  * Allocate a codec structure and the polynom arrays for faster
  * en/decoding. Fill the arrays according to the given parameters.
  */
 static struct rs_codec *codec_init(int symsize, int gfpoly, int (*gffunc)(int),
 				   int fcr, int prim, int nroots, gfp_t gfp)
 {
 	int i, j, sr, root, iprim;
 	struct rs_codec *rs;

 	rs = kzalloc(sizeof(*rs), gfp);
 	if (!rs)
 		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;
 	rs->gffunc = gffunc;

 	/* Allocate the arrays */
 	rs->alpha_to = kmalloc_array(rs->nn + 1, sizeof(uint16_t), gfp);
 	if (rs->alpha_to == NULL)
 		goto err;

 	rs->index_of = kmalloc_array(rs->nn + 1, sizeof(uint16_t), gfp);
 	if (rs->index_of == NULL)
 		goto err;

 	rs->genpoly = kmalloc_array(rs->nroots + 1, sizeof(uint16_t), gfp);
 	if(rs->genpoly == NULL)
 		goto err;

 	/* Generate Galois field lookup tables */
 	rs->index_of[0] = rs->nn;	/* log(zero) = -inf */
 	rs->alpha_to[rs->nn] = 0;	/* alpha**-inf = 0 */
 	if (gfpoly) {
 		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;
 		}
 	} else {
 		sr = gffunc(0);
 		for (i = 0; i < rs->nn; i++) {
 			rs->index_of[sr] = i;
 			rs->alpha_to[i] = sr;
 			sr = gffunc(sr);
 		}
 	}
 	/* If it's not primitive, exit */
 	if(sr != rs->alpha_to[0])
 		goto err;

 	/* 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]];

 	rs->users = 1;
 	list_add(&rs->list, &codec_list);
 	return rs;

 err:
 	kfree(rs->genpoly);
 	kfree(rs->index_of);
 	kfree(rs->alpha_to);
 	kfree(rs);
 	return NULL;
 }


 /**
  *  free_rs - Free the rs control structure
  *  @rs:	The control structure which is not longer used by the
  *		caller
  *
  * Free the control structure. If @rs is the last user of the associated
  * codec, free the codec as well.
  */
 void free_rs(struct rs_control *rs)
 {
 	struct rs_codec *cd;

 	if (!rs)
 		return;

 	cd = rs->codec;
 	mutex_lock(&rslistlock);
 	cd->users--;
 	if(!cd->users) {
 		list_del(&cd->list);
 		kfree(cd->alpha_to);
 		kfree(cd->index_of);
 		kfree(cd->genpoly);
 		kfree(cd);
 	}
 	mutex_unlock(&rslistlock);
 	kfree(rs);
 }
 EXPORT_SYMBOL_GPL(free_rs);

 /**
  * init_rs_internal - Allocate rs control, find a matching codec or allocate a new one
  *  @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;
  *  @gffunc:	pointer to function to generate the next field element,
  *		or the multiplicative identity element if given 0.  Used
  *		instead of gfpoly if gfpoly is 0
  *  @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)
  *  @gfp:	GFP_ flags for allocations
  */
 static struct rs_control *init_rs_internal(int symsize, int gfpoly,
 					   int (*gffunc)(int), int fcr,
 					   int prim, int nroots, gfp_t gfp)
 {
 	struct list_head *tmp;
 	struct rs_control *rs;
 	unsigned int bsize;

 	/* 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))
 		return NULL;

 	/*
 	 * The decoder needs buffers in each control struct instance to
 	 * avoid variable size or large fixed size allocations on
 	 * stack. Size the buffers to arrays of [nroots + 1].
 	 */
 	bsize = sizeof(uint16_t) * RS_DECODE_NUM_BUFFERS * (nroots + 1);
 	rs = kzalloc(sizeof(*rs) + bsize, gfp);
 	if (!rs)
 		return NULL;

 	mutex_lock(&rslistlock);

 	/* Walk through the list and look for a matching entry */
 	list_for_each(tmp, &codec_list) {
 		struct rs_codec *cd = list_entry(tmp, struct rs_codec, list);

 		if (symsize != cd->mm)
 			continue;
 		if (gfpoly != cd->gfpoly)
 			continue;
 		if (gffunc != cd->gffunc)
 			continue;
 		if (fcr != cd->fcr)
 			continue;
 		if (prim != cd->prim)
 			continue;
 		if (nroots != cd->nroots)
 			continue;
 		/* We have a matching one already */
 		cd->users++;
 		rs->codec = cd;
 		goto out;
 	}

 	/* Create a new one */
 	rs->codec = codec_init(symsize, gfpoly, gffunc, fcr, prim, nroots, gfp);
 	if (!rs->codec) {
 		kfree(rs);
 		rs = NULL;
 	}
 out:
 	mutex_unlock(&rslistlock);
 	return rs;
 }

 /**
  * init_rs_gfp - Create a RS control struct and initialize it
  *  @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)
  *  @gfp:	Memory allocation flags.
  */
 struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
 			       int nroots, gfp_t gfp)
 {
 	return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots, gfp);
 }
 EXPORT_SYMBOL_GPL(init_rs_gfp);

 /**
  * init_rs_non_canonical - Allocate rs control struct for fields with
  *                         non-canonical representation
  *  @symsize:	the symbol size (number of bits)
  *  @gffunc:	pointer to function to generate the next field element,
  *		or the multiplicative identity element if given 0.  Used
  *		instead of gfpoly if gfpoly is 0
  *  @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_non_canonical(int symsize, int (*gffunc)(int),
 					 int fcr, int prim, int nroots)
 {
 	return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots,
 				GFP_KERNEL);
 }
 EXPORT_SYMBOL_GPL(init_rs_non_canonical);

 #ifdef CONFIG_REED_SOLOMON_ENC8
 /**
  *  encode_rs8 - Calculate the parity for data values (8bit data width)
  *  @rsc:	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 *rsc, 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)
  *  @rsc:	the rs control structure
  *  @data:	data field of a given type
  *  @par:	received parity data field
  *  @len:	data length
  *  @s: 	syndrome data field, must be in index form
  *		(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.
  *
  *  Note: The rs_control struct @rsc contains buffers which are used for
  *  decoding, so the caller has to ensure that decoder invocations are
  *  serialized.
  *
  *  Returns the number of corrected symbols or -EBADMSG for uncorrectable
  *  errors. The count includes errors in the parity.
  */
 int decode_rs8(struct rs_control *rsc, 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)
  *  @rsc:	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 *rsc, 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)
  *  @rsc:	the rs control structure
  *  @data:	data field of a given type
  *  @par:	received parity data field
  *  @len:	data length
  *  @s: 	syndrome data field, must be in index form
  *		(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.
  *
  *  Note: The rc_control struct @rsc contains buffers which are used for
  *  decoding, so the caller has to ensure that decoder invocations are
  *  serialized.
  *
  *  Returns the number of corrected symbols or -EBADMSG for uncorrectable
  *  errors. The count includes errors in the parity.
  */
 int decode_rs16(struct rs_control *rsc, 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

 MODULE_LICENSE("GPL");
 MODULE_DESCRIPTION("Reed Solomon encoder/decoder");
 MODULE_AUTHOR("Phil Karn, Thomas Gleixner");
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Generic Reed Solomon encoder / decoder library
	*
	* Copyright (C) 2004 Thomas Gleixner ([email protected])
	*
	* Reed Solomon code lifted from reed solomon library written by Phil Karn
	* Copyright 2002 Phil Karn, KA9Q
	*
	* 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. The control struct is unique per instance.
	* It points to a codec which can be shared by multiple control structures.
	* If a codec is newly allocated 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 <linux/mutex.h>

	enum {
	RS_DECODE_LAMBDA,
	RS_DECODE_SYN,
	RS_DECODE_B,
	RS_DECODE_T,
	RS_DECODE_OMEGA,
	RS_DECODE_ROOT,
	RS_DECODE_REG,
	RS_DECODE_LOC,
	RS_DECODE_NUM_BUFFERS
	};

	/* This list holds all currently allocated rs codec structures */
	static LIST_HEAD(codec_list);
	/* Protection for the list */
	static DEFINE_MUTEX(rslistlock);

	/**
	* codec_init - Initialize a Reed-Solomon codec
	* @symsize: symbol size, bits (1-8)
	* @gfpoly: Field generator polynomial coefficients
	* @gffunc: Field generator function
	* @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)
	* @gfp: GFP_ flags for allocations
	*
	* Allocate a codec structure and the polynom arrays for faster
	* en/decoding. Fill the arrays according to the given parameters.
	*/
	static struct rs_codec codec_init(int symsize, int gfpoly, int (gffunc)(int),
	int fcr, int prim, int nroots, gfp_t gfp)
	{
	int i, j, sr, root, iprim;
	struct rs_codec *rs;

	rs = kzalloc(sizeof(*rs), gfp);
	if (!rs)
	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;
	rs->gffunc = gffunc;

	/* Allocate the arrays */
	rs->alpha_to = kmalloc_array(rs->nn + 1, sizeof(uint16_t), gfp);
	if (rs->alpha_to == NULL)
	goto err;

	rs->index_of = kmalloc_array(rs->nn + 1, sizeof(uint16_t), gfp);
	if (rs->index_of == NULL)
	goto err;

	rs->genpoly = kmalloc_array(rs->nroots + 1, sizeof(uint16_t), gfp);
	if(rs->genpoly == NULL)
	goto err;

	/* Generate Galois field lookup tables */
	rs->index_of[0] = rs->nn; /* log(zero) = -inf */
	rs->alpha_to[rs->nn] = 0; /* alpha*-inf = 0 /
	if (gfpoly) {
	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;
	}
	} else {
	sr = gffunc(0);
	for (i = 0; i < rs->nn; i++) {
	rs->index_of[sr] = i;
	rs->alpha_to[i] = sr;
	sr = gffunc(sr);
	}
	}
	/* If it's not primitive, exit */
	if(sr != rs->alpha_to[0])
	goto err;

	/* 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]];

	rs->users = 1;
	list_add(&rs->list, &codec_list);
	return rs;

	err:
	kfree(rs->genpoly);
	kfree(rs->index_of);
	kfree(rs->alpha_to);
	kfree(rs);
	return NULL;
	}


	/**
	* free_rs - Free the rs control structure
	* @rs: The control structure which is not longer used by the
	* caller
	*
	* Free the control structure. If @rs is the last user of the associated
	* codec, free the codec as well.
	*/
	void free_rs(struct rs_control *rs)
	{
	struct rs_codec *cd;

	if (!rs)
	return;

	cd = rs->codec;
	mutex_lock(&rslistlock);
	cd->users--;
	if(!cd->users) {
	list_del(&cd->list);
	kfree(cd->alpha_to);
	kfree(cd->index_of);
	kfree(cd->genpoly);
	kfree(cd);
	}
	mutex_unlock(&rslistlock);
	kfree(rs);
	}
	EXPORT_SYMBOL_GPL(free_rs);

	/**
	* init_rs_internal - Allocate rs control, find a matching codec or allocate a new one
	* @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;
	* @gffunc: pointer to function to generate the next field element,
	* or the multiplicative identity element if given 0. Used
	* instead of gfpoly if gfpoly is 0
	* @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)
	* @gfp: GFP_ flags for allocations
	*/
	static struct rs_control *init_rs_internal(int symsize, int gfpoly,
	int (*gffunc)(int), int fcr,
	int prim, int nroots, gfp_t gfp)
	{
	struct list_head *tmp;
	struct rs_control *rs;
	unsigned int bsize;

	/* 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))
	return NULL;

	/*
	* The decoder needs buffers in each control struct instance to
	* avoid variable size or large fixed size allocations on
	* stack. Size the buffers to arrays of [nroots + 1].
	*/
	bsize = sizeof(uint16_t) * RS_DECODE_NUM_BUFFERS * (nroots + 1);
	rs = kzalloc(sizeof(*rs) + bsize, gfp);
	if (!rs)
	return NULL;

	mutex_lock(&rslistlock);

	/* Walk through the list and look for a matching entry */
	list_for_each(tmp, &codec_list) {
	struct rs_codec *cd = list_entry(tmp, struct rs_codec, list);

	if (symsize != cd->mm)
	continue;
	if (gfpoly != cd->gfpoly)
	continue;
	if (gffunc != cd->gffunc)
	continue;
	if (fcr != cd->fcr)
	continue;
	if (prim != cd->prim)
	continue;
	if (nroots != cd->nroots)
	continue;
	/* We have a matching one already */
	cd->users++;
	rs->codec = cd;
	goto out;
	}

	/* Create a new one */
	rs->codec = codec_init(symsize, gfpoly, gffunc, fcr, prim, nroots, gfp);
	if (!rs->codec) {
	kfree(rs);
	rs = NULL;
	}
	out:
	mutex_unlock(&rslistlock);
	return rs;
	}

	/**
	* init_rs_gfp - Create a RS control struct and initialize it
	* @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)
	* @gfp: Memory allocation flags.
	*/
	struct rs_control *init_rs_gfp(int symsize, int gfpoly, int fcr, int prim,
	int nroots, gfp_t gfp)
	{
	return init_rs_internal(symsize, gfpoly, NULL, fcr, prim, nroots, gfp);
	}
	EXPORT_SYMBOL_GPL(init_rs_gfp);

	/**
	* init_rs_non_canonical - Allocate rs control struct for fields with
	* non-canonical representation
	* @symsize: the symbol size (number of bits)
	* @gffunc: pointer to function to generate the next field element,
	* or the multiplicative identity element if given 0. Used
	* instead of gfpoly if gfpoly is 0
	* @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_non_canonical(int symsize, int (gffunc)(int),
	int fcr, int prim, int nroots)
	{
	return init_rs_internal(symsize, 0, gffunc, fcr, prim, nroots,
	GFP_KERNEL);
	}
	EXPORT_SYMBOL_GPL(init_rs_non_canonical);

	#ifdef CONFIG_REED_SOLOMON_ENC8
	/**
	* encode_rs8 - Calculate the parity for data values (8bit data width)
	* @rsc: 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 rsc, 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)
	* @rsc: the rs control structure
	* @data: data field of a given type
	* @par: received parity data field
	* @len: data length
	* @s: syndrome data field, must be in index form
	* (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.
	*
	* Note: The rs_control struct @rsc contains buffers which are used for
	* decoding, so the caller has to ensure that decoder invocations are
	* serialized.
	*
	* Returns the number of corrected symbols or -EBADMSG for uncorrectable
	* errors. The count includes errors in the parity.
	*/
	int decode_rs8(struct rs_control rsc, 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)
	* @rsc: 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 rsc, 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)
	* @rsc: the rs control structure
	* @data: data field of a given type
	* @par: received parity data field
	* @len: data length
	* @s: syndrome data field, must be in index form
	* (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.
	*
	* Note: The rc_control struct @rsc contains buffers which are used for
	* decoding, so the caller has to ensure that decoder invocations are
	* serialized.
	*
	* Returns the number of corrected symbols or -EBADMSG for uncorrectable
	* errors. The count includes errors in the parity.
	*/
	int decode_rs16(struct rs_control rsc, 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

	MODULE_LICENSE("GPL");
	MODULE_DESCRIPTION("Reed Solomon encoder/decoder");
	MODULE_AUTHOR("Phil Karn, Thomas Gleixner");