crc32.c

uboot200903最新版本的通用uboot

/*
 * Oct 15, 2000 Matt Domsch <[e-mail]>
 * Nicer crc32 functions/docs submitted by [e-mail].  Thanks!
 * Code was from the public domain, copyright abandoned.  Code was
 * subsequently included in the kernel, thus was re-licensed under the
 * GNU GPL v2.
 *
 * Oct 12, 2000 Matt Domsch <[e-mail]>
 * Same crc32 function was used in 5 other places in the kernel.
 * I made one version, and deleted the others.
 * There are various incantations of crc32().  Some use a seed of 0 or ~0.
 * Some xor at the end with ~0.  The generic crc32() function takes
 * seed as an argument, and doesn't xor at the end.  Then individual
 * users can do whatever they need.
 *   drivers/net/smc9194.c uses seed ~0, doesn't xor with ~0.
 *   fs/jffs2 uses seed 0, doesn't xor with ~0.
 *   fs/partitions/efi.c uses seed ~0, xor's with ~0.
 *
 * This source code is licensed under the GNU General Public License,
 * Version 2.  See the file COPYING for more details.
 */

#ifdef UBI_LINUX
#include <linux/crc32.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/compiler.h>
#endif
#include <linux/types.h>

#include <asm/byteorder.h>

#ifdef UBI_LINUX
#include <linux/slab.h>
#include <linux/init.h>
#include <asm/atomic.h>
#endif
#include "crc32defs.h"
#define CRC_LE_BITS 8

# define __force
#ifndef __constant_cpu_to_le32
#define __constant_cpu_to_le32(x) ((__force __le32)(__u32)(x))
#endif
#ifndef __constant_le32_to_cpu
#define __constant_le32_to_cpu(x) ((__force __u32)(__le32)(x))
#endif

#if CRC_LE_BITS == 8
#define tole(x) __constant_cpu_to_le32(x)
#define tobe(x) __constant_cpu_to_be32(x)
#else
#define tole(x) (x)
#define tobe(x) (x)
#endif
#include "crc32table.h"
#ifdef UBI_LINUX
MODULE_AUTHOR("Matt Domsch <[e-mail]>");
MODULE_DESCRIPTION("Ethernet CRC32 calculations");
MODULE_LICENSE("GPL");
#endif
/**
 * crc32_le() - Calculate bitwise little-endian Ethernet AUTODIN II CRC32
 * @crc: seed value for computation.  ~0 for Ethernet, sometimes 0 for
 *	other uses, or the previous crc32 value if computing incrementally.
 * @p: pointer to buffer over which CRC is run
 * @len: length of buffer @p
 */
u32  crc32_le(u32 crc, unsigned char const *p, size_t len);

#if CRC_LE_BITS == 1
/*
 * In fact, the table-based code will work in this case, but it can be
 * simplified by inlining the table in ?: form.
 */

u32 crc32_le(u32 crc, unsigned char const *p, size_t len)
{
	int i;
	while (len--) {
		crc ^= *p++;
		for (i = 0; i < 8; i++)
			crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0);
	}
	return crc;
}
#else				/* Table-based approach */

u32 crc32_le(u32 crc, unsigned char const *p, size_t len)
{
# if CRC_LE_BITS == 8
	const u32      *b =(u32 *)p;
	const u32      *tab = crc32table_le;

# ifdef __LITTLE_ENDIAN
#  define DO_CRC(x) crc = tab[ (crc ^ (x)) & 255 ] ^ (crc>>8)
# else
#  define DO_CRC(x) crc = tab[ ((crc >> 24) ^ (x)) & 255] ^ (crc<<8)
# endif
	/* printf("Crc32_le crc=%x\n",crc); */
	crc = __cpu_to_le32(crc);
	/* Align it */
	if((((long)b)&3 && len)){
		do {
			u8 *p = (u8 *)b;
			DO_CRC(*p++);
			b = (void *)p;
		} while ((--len) && ((long)b)&3 );
	}
	if((len >= 4)){
		/* load data 32 bits wide, xor data 32 bits wide. */
		size_t save_len = len & 3;
	        len = len >> 2;
		--b; /* use pre increment below(*++b) for speed */
		do {
			crc ^= *++b;
			DO_CRC(0);
			DO_CRC(0);
			DO_CRC(0);
			DO_CRC(0);
		} while (--len);
		b++; /* point to next byte(s) */
		len = save_len;
	}
	/* And the last few bytes */
	if(len){
		do {
			u8 *p = (u8 *)b;
			DO_CRC(*p++);
			b = (void *)p;
		} while (--len);
	}

	return __le32_to_cpu(crc);
#undef ENDIAN_SHIFT
#undef DO_CRC

# elif CRC_LE_BITS == 4
	while (len--) {
		crc ^= *p++;
		crc = (crc >> 4) ^ crc32table_le[crc & 15];
		crc = (crc >> 4) ^ crc32table_le[crc & 15];
	}
	return crc;
# elif CRC_LE_BITS == 2
	while (len--) {
		crc ^= *p++;
		crc = (crc >> 2) ^ crc32table_le[crc & 3];
		crc = (crc >> 2) ^ crc32table_le[crc & 3];
		crc = (crc >> 2) ^ crc32table_le[crc & 3];
		crc = (crc >> 2) ^ crc32table_le[crc & 3];
	}
	return crc;
# endif
}
#endif
#ifdef UBI_LINUX
/**
 * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
 * @crc: seed value for computation.  ~0 for Ethernet, sometimes 0 for
 *	other uses, or the previous crc32 value if computing incrementally.
 * @p: pointer to buffer over which CRC is run
 * @len: length of buffer @p
 */
u32 __attribute_pure__ crc32_be(u32 crc, unsigned char const *p, size_t len);

#if CRC_BE_BITS == 1
/*
 * In fact, the table-based code will work in this case, but it can be
 * simplified by inlining the table in ?: form.
 */

u32 __attribute_pure__ crc32_be(u32 crc, unsigned char const *p, size_t len)
{
	int i;
	while (len--) {
		crc ^= *p++ << 24;
		for (i = 0; i < 8; i++)
			crc =
			    (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE :
					  0);
	}
	return crc;
}

#else				/* Table-based approach */
u32 __attribute_pure__ crc32_be(u32 crc, unsigned char const *p, size_t len)
{
# if CRC_BE_BITS == 8
	const u32      *b =(u32 *)p;
	const u32      *tab = crc32table_be;

# ifdef __LITTLE_ENDIAN
#  define DO_CRC(x) crc = tab[ (crc ^ (x)) & 255 ] ^ (crc>>8)
# else
#  define DO_CRC(x) crc = tab[ ((crc >> 24) ^ (x)) & 255] ^ (crc<<8)
# endif

	crc = __cpu_to_be32(crc);
	/* Align it */
	if(unlikely(((long)b)&3 && len)){
		do {
			u8 *p = (u8 *)b;
			DO_CRC(*p++);
			b = (u32 *)p;
		} while ((--len) && ((long)b)&3 );
	}
	if(likely(len >= 4)){
		/* load data 32 bits wide, xor data 32 bits wide. */
		size_t save_len = len & 3;
	        len = len >> 2;
		--b; /* use pre increment below(*++b) for speed */
		do {
			crc ^= *++b;
			DO_CRC(0);
			DO_CRC(0);
			DO_CRC(0);
			DO_CRC(0);
		} while (--len);
		b++; /* point to next byte(s) */
		len = save_len;
	}
	/* And the last few bytes */
	if(len){
		do {
			u8 *p = (u8 *)b;
			DO_CRC(*p++);
			b = (void *)p;
		} while (--len);
	}
	return __be32_to_cpu(crc);
#undef ENDIAN_SHIFT
#undef DO_CRC

# elif CRC_BE_BITS == 4
	while (len--) {
		crc ^= *p++ << 24;
		crc = (crc << 4) ^ crc32table_be[crc >> 28];
		crc = (crc << 4) ^ crc32table_be[crc >> 28];
	}
	return crc;
# elif CRC_BE_BITS == 2
	while (len--) {
		crc ^= *p++ << 24;
		crc = (crc << 2) ^ crc32table_be[crc >> 30];
		crc = (crc << 2) ^ crc32table_be[crc >> 30];
		crc = (crc << 2) ^ crc32table_be[crc >> 30];
		crc = (crc << 2) ^ crc32table_be[crc >> 30];
	}
	return crc;
# endif
}
#endif

EXPORT_SYMBOL(crc32_le);
EXPORT_SYMBOL(crc32_be);
#endif
/*
 * A brief CRC tutorial.
 *