347 lines
9.3 KiB
C
347 lines
9.3 KiB
C
/*
|
|
* Aug 8, 2011 Bob Pearson with help from Joakim Tjernlund and George Spelvin
|
|
* cleaned up code to current version of sparse and added the slicing-by-8
|
|
* algorithm to the closely similar existing slicing-by-4 algorithm.
|
|
*
|
|
* Oct 15, 2000 Matt Domsch <Matt_Domsch@dell.com>
|
|
* Nicer crc32 functions/docs submitted by linux@horizon.com. 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 <Matt_Domsch@dell.com>
|
|
* 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.
|
|
*/
|
|
|
|
/* see: Documentation/crc32.txt for a description of algorithms */
|
|
|
|
#include <linux/crc32.h>
|
|
#include <linux/crc32poly.h>
|
|
#include <linux/module.h>
|
|
#include <linux/types.h>
|
|
#include <linux/sched.h>
|
|
#include "crc32defs.h"
|
|
|
|
#if CRC_LE_BITS > 8
|
|
# define tole(x) ((__force u32) cpu_to_le32(x))
|
|
#else
|
|
# define tole(x) (x)
|
|
#endif
|
|
|
|
#if CRC_BE_BITS > 8
|
|
# define tobe(x) ((__force u32) cpu_to_be32(x))
|
|
#else
|
|
# define tobe(x) (x)
|
|
#endif
|
|
|
|
#include "crc32table.h"
|
|
|
|
MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>");
|
|
MODULE_DESCRIPTION("Various CRC32 calculations");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
|
|
|
|
/* implements slicing-by-4 or slicing-by-8 algorithm */
|
|
static inline u32 __pure
|
|
crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
|
|
{
|
|
# ifdef __LITTLE_ENDIAN
|
|
# define DO_CRC(x) crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8)
|
|
# define DO_CRC4 (t3[(q) & 255] ^ t2[(q >> 8) & 255] ^ \
|
|
t1[(q >> 16) & 255] ^ t0[(q >> 24) & 255])
|
|
# define DO_CRC8 (t7[(q) & 255] ^ t6[(q >> 8) & 255] ^ \
|
|
t5[(q >> 16) & 255] ^ t4[(q >> 24) & 255])
|
|
# else
|
|
# define DO_CRC(x) crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
|
|
# define DO_CRC4 (t0[(q) & 255] ^ t1[(q >> 8) & 255] ^ \
|
|
t2[(q >> 16) & 255] ^ t3[(q >> 24) & 255])
|
|
# define DO_CRC8 (t4[(q) & 255] ^ t5[(q >> 8) & 255] ^ \
|
|
t6[(q >> 16) & 255] ^ t7[(q >> 24) & 255])
|
|
# endif
|
|
const u32 *b;
|
|
size_t rem_len;
|
|
# ifdef CONFIG_X86
|
|
size_t i;
|
|
# endif
|
|
const u32 *t0=tab[0], *t1=tab[1], *t2=tab[2], *t3=tab[3];
|
|
# if CRC_LE_BITS != 32
|
|
const u32 *t4 = tab[4], *t5 = tab[5], *t6 = tab[6], *t7 = tab[7];
|
|
# endif
|
|
u32 q;
|
|
|
|
/* Align it */
|
|
if (unlikely((long)buf & 3 && len)) {
|
|
do {
|
|
DO_CRC(*buf++);
|
|
} while ((--len) && ((long)buf)&3);
|
|
}
|
|
|
|
# if CRC_LE_BITS == 32
|
|
rem_len = len & 3;
|
|
len = len >> 2;
|
|
# else
|
|
rem_len = len & 7;
|
|
len = len >> 3;
|
|
# endif
|
|
|
|
b = (const u32 *)buf;
|
|
# ifdef CONFIG_X86
|
|
--b;
|
|
for (i = 0; i < len; i++) {
|
|
# else
|
|
for (--b; len; --len) {
|
|
# endif
|
|
q = crc ^ *++b; /* use pre increment for speed */
|
|
# if CRC_LE_BITS == 32
|
|
crc = DO_CRC4;
|
|
# else
|
|
crc = DO_CRC8;
|
|
q = *++b;
|
|
crc ^= DO_CRC4;
|
|
# endif
|
|
}
|
|
len = rem_len;
|
|
/* And the last few bytes */
|
|
if (len) {
|
|
u8 *p = (u8 *)(b + 1) - 1;
|
|
# ifdef CONFIG_X86
|
|
for (i = 0; i < len; i++)
|
|
DO_CRC(*++p); /* use pre increment for speed */
|
|
# else
|
|
do {
|
|
DO_CRC(*++p); /* use pre increment for speed */
|
|
} while (--len);
|
|
# endif
|
|
}
|
|
return crc;
|
|
#undef DO_CRC
|
|
#undef DO_CRC4
|
|
#undef DO_CRC8
|
|
}
|
|
#endif
|
|
|
|
|
|
/**
|
|
* crc32_le_generic() - Calculate bitwise little-endian Ethernet AUTODIN II
|
|
* CRC32/CRC32C
|
|
* @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for other
|
|
* uses, or the previous crc32/crc32c value if computing incrementally.
|
|
* @p: pointer to buffer over which CRC32/CRC32C is run
|
|
* @len: length of buffer @p
|
|
* @tab: little-endian Ethernet table
|
|
* @polynomial: CRC32/CRC32c LE polynomial
|
|
*/
|
|
static inline u32 __pure crc32_le_generic(u32 crc, unsigned char const *p,
|
|
size_t len, const u32 (*tab)[256],
|
|
u32 polynomial)
|
|
{
|
|
#if CRC_LE_BITS == 1
|
|
int i;
|
|
while (len--) {
|
|
crc ^= *p++;
|
|
for (i = 0; i < 8; i++)
|
|
crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
|
|
}
|
|
# elif CRC_LE_BITS == 2
|
|
while (len--) {
|
|
crc ^= *p++;
|
|
crc = (crc >> 2) ^ tab[0][crc & 3];
|
|
crc = (crc >> 2) ^ tab[0][crc & 3];
|
|
crc = (crc >> 2) ^ tab[0][crc & 3];
|
|
crc = (crc >> 2) ^ tab[0][crc & 3];
|
|
}
|
|
# elif CRC_LE_BITS == 4
|
|
while (len--) {
|
|
crc ^= *p++;
|
|
crc = (crc >> 4) ^ tab[0][crc & 15];
|
|
crc = (crc >> 4) ^ tab[0][crc & 15];
|
|
}
|
|
# elif CRC_LE_BITS == 8
|
|
/* aka Sarwate algorithm */
|
|
while (len--) {
|
|
crc ^= *p++;
|
|
crc = (crc >> 8) ^ tab[0][crc & 255];
|
|
}
|
|
# else
|
|
crc = (__force u32) __cpu_to_le32(crc);
|
|
crc = crc32_body(crc, p, len, tab);
|
|
crc = __le32_to_cpu((__force __le32)crc);
|
|
#endif
|
|
return crc;
|
|
}
|
|
|
|
#if CRC_LE_BITS == 1
|
|
u32 __pure __weak crc32_le(u32 crc, unsigned char const *p, size_t len)
|
|
{
|
|
return crc32_le_generic(crc, p, len, NULL, CRC32_POLY_LE);
|
|
}
|
|
u32 __pure __weak __crc32c_le(u32 crc, unsigned char const *p, size_t len)
|
|
{
|
|
return crc32_le_generic(crc, p, len, NULL, CRC32C_POLY_LE);
|
|
}
|
|
#else
|
|
u32 __pure __weak crc32_le(u32 crc, unsigned char const *p, size_t len)
|
|
{
|
|
return crc32_le_generic(crc, p, len,
|
|
(const u32 (*)[256])crc32table_le, CRC32_POLY_LE);
|
|
}
|
|
u32 __pure __weak __crc32c_le(u32 crc, unsigned char const *p, size_t len)
|
|
{
|
|
return crc32_le_generic(crc, p, len,
|
|
(const u32 (*)[256])crc32ctable_le, CRC32C_POLY_LE);
|
|
}
|
|
#endif
|
|
EXPORT_SYMBOL(crc32_le);
|
|
EXPORT_SYMBOL(__crc32c_le);
|
|
|
|
u32 crc32_le_base(u32, unsigned char const *, size_t) __alias(crc32_le);
|
|
u32 __crc32c_le_base(u32, unsigned char const *, size_t) __alias(__crc32c_le);
|
|
|
|
/*
|
|
* This multiplies the polynomials x and y modulo the given modulus.
|
|
* This follows the "little-endian" CRC convention that the lsbit
|
|
* represents the highest power of x, and the msbit represents x^0.
|
|
*/
|
|
static u32 __attribute_const__ gf2_multiply(u32 x, u32 y, u32 modulus)
|
|
{
|
|
u32 product = x & 1 ? y : 0;
|
|
int i;
|
|
|
|
for (i = 0; i < 31; i++) {
|
|
product = (product >> 1) ^ (product & 1 ? modulus : 0);
|
|
x >>= 1;
|
|
product ^= x & 1 ? y : 0;
|
|
}
|
|
|
|
return product;
|
|
}
|
|
|
|
/**
|
|
* crc32_generic_shift - Append @len 0 bytes to crc, in logarithmic time
|
|
* @crc: The original little-endian CRC (i.e. lsbit is x^31 coefficient)
|
|
* @len: The number of bytes. @crc is multiplied by x^(8*@len)
|
|
* @polynomial: The modulus used to reduce the result to 32 bits.
|
|
*
|
|
* It's possible to parallelize CRC computations by computing a CRC
|
|
* over separate ranges of a buffer, then summing them.
|
|
* This shifts the given CRC by 8*len bits (i.e. produces the same effect
|
|
* as appending len bytes of zero to the data), in time proportional
|
|
* to log(len).
|
|
*/
|
|
static u32 __attribute_const__ crc32_generic_shift(u32 crc, size_t len,
|
|
u32 polynomial)
|
|
{
|
|
u32 power = polynomial; /* CRC of x^32 */
|
|
int i;
|
|
|
|
/* Shift up to 32 bits in the simple linear way */
|
|
for (i = 0; i < 8 * (int)(len & 3); i++)
|
|
crc = (crc >> 1) ^ (crc & 1 ? polynomial : 0);
|
|
|
|
len >>= 2;
|
|
if (!len)
|
|
return crc;
|
|
|
|
for (;;) {
|
|
/* "power" is x^(2^i), modulo the polynomial */
|
|
if (len & 1)
|
|
crc = gf2_multiply(crc, power, polynomial);
|
|
|
|
len >>= 1;
|
|
if (!len)
|
|
break;
|
|
|
|
/* Square power, advancing to x^(2^(i+1)) */
|
|
power = gf2_multiply(power, power, polynomial);
|
|
}
|
|
|
|
return crc;
|
|
}
|
|
|
|
u32 __attribute_const__ crc32_le_shift(u32 crc, size_t len)
|
|
{
|
|
return crc32_generic_shift(crc, len, CRC32_POLY_LE);
|
|
}
|
|
|
|
u32 __attribute_const__ __crc32c_le_shift(u32 crc, size_t len)
|
|
{
|
|
return crc32_generic_shift(crc, len, CRC32C_POLY_LE);
|
|
}
|
|
EXPORT_SYMBOL(crc32_le_shift);
|
|
EXPORT_SYMBOL(__crc32c_le_shift);
|
|
|
|
/**
|
|
* crc32_be_generic() - 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 CRC32 is run
|
|
* @len: length of buffer @p
|
|
* @tab: big-endian Ethernet table
|
|
* @polynomial: CRC32 BE polynomial
|
|
*/
|
|
static inline u32 __pure crc32_be_generic(u32 crc, unsigned char const *p,
|
|
size_t len, const u32 (*tab)[256],
|
|
u32 polynomial)
|
|
{
|
|
#if CRC_BE_BITS == 1
|
|
int i;
|
|
while (len--) {
|
|
crc ^= *p++ << 24;
|
|
for (i = 0; i < 8; i++)
|
|
crc =
|
|
(crc << 1) ^ ((crc & 0x80000000) ? polynomial :
|
|
0);
|
|
}
|
|
# elif CRC_BE_BITS == 2
|
|
while (len--) {
|
|
crc ^= *p++ << 24;
|
|
crc = (crc << 2) ^ tab[0][crc >> 30];
|
|
crc = (crc << 2) ^ tab[0][crc >> 30];
|
|
crc = (crc << 2) ^ tab[0][crc >> 30];
|
|
crc = (crc << 2) ^ tab[0][crc >> 30];
|
|
}
|
|
# elif CRC_BE_BITS == 4
|
|
while (len--) {
|
|
crc ^= *p++ << 24;
|
|
crc = (crc << 4) ^ tab[0][crc >> 28];
|
|
crc = (crc << 4) ^ tab[0][crc >> 28];
|
|
}
|
|
# elif CRC_BE_BITS == 8
|
|
while (len--) {
|
|
crc ^= *p++ << 24;
|
|
crc = (crc << 8) ^ tab[0][crc >> 24];
|
|
}
|
|
# else
|
|
crc = (__force u32) __cpu_to_be32(crc);
|
|
crc = crc32_body(crc, p, len, tab);
|
|
crc = __be32_to_cpu((__force __be32)crc);
|
|
# endif
|
|
return crc;
|
|
}
|
|
|
|
#if CRC_LE_BITS == 1
|
|
u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
|
|
{
|
|
return crc32_be_generic(crc, p, len, NULL, CRC32_POLY_BE);
|
|
}
|
|
#else
|
|
u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
|
|
{
|
|
return crc32_be_generic(crc, p, len,
|
|
(const u32 (*)[256])crc32table_be, CRC32_POLY_BE);
|
|
}
|
|
#endif
|
|
EXPORT_SYMBOL(crc32_be);
|