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crc32: bolt on crc32c

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Reuse the existing crc32 code to stamp out a crc32c implementation.

Signed-off-by: Darrick J. Wong <djwong@us.ibm.com>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Bob Pearson <rpearson@systemfabricworks.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Darrick J. Wong 2012-03-23 15:02:25 -07:00 committed by Linus Torvalds
parent 78dff41897
commit 46c5801eaf
5 changed files with 97 additions and 34 deletions
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2
include/linux/crc32.h
View file

@ -11,6 +11,8 @@
extern u32 crc32_le(u32 crc, unsigned char const *p, size_t len); extern u32 crc32_le(u32 crc, unsigned char const *p, size_t len);
extern u32 crc32_be(u32 crc, unsigned char const *p, size_t len); extern u32 crc32_be(u32 crc, unsigned char const *p, size_t len);
extern u32 __crc32c_le(u32 crc, unsigned char const *p, size_t len);
#define crc32(seed, data, length) crc32_le(seed, (unsigned char const *)(data), length) #define crc32(seed, data, length) crc32_le(seed, (unsigned char const *)(data), length)
/* /*

8
lib/Kconfig
View file

@ -61,14 +61,14 @@ config CRC_ITU_T
functions require M here. functions require M here.
config CRC32 config CRC32
tristate "CRC32 functions" tristate "CRC32/CRC32c functions"
default y default y
select BITREVERSE select BITREVERSE
help help
This option is provided for the case where no in-kernel-tree This option is provided for the case where no in-kernel-tree
modules require CRC32 functions, but a module built outside the modules require CRC32/CRC32c functions, but a module built outside
kernel tree does. Such modules that use library CRC32 functions the kernel tree does. Such modules that use library CRC32/CRC32c
require M here. functions require M here.
config CRC32_SELFTEST config CRC32_SELFTEST
bool "CRC32 perform self test on init" bool "CRC32 perform self test on init"

79
lib/crc32.c
View file

@ -46,7 +46,7 @@
#include "crc32table.h" #include "crc32table.h"
MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>"); MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>");
MODULE_DESCRIPTION("Ethernet CRC32 calculations"); MODULE_DESCRIPTION("Various CRC32 calculations");
MODULE_LICENSE("GPL"); MODULE_LICENSE("GPL");
#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8 #if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
@ -135,45 +135,66 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
* @p: pointer to buffer over which CRC is run * @p: pointer to buffer over which CRC is run
* @len: length of buffer @p * @len: length of buffer @p
*/ */
u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len) 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 #if CRC_LE_BITS == 1
int i; int i;
while (len--) { while (len--) {
crc ^= *p++; crc ^= *p++;
for (i = 0; i < 8; i++) for (i = 0; i < 8; i++)
crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0); crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
} }
# elif CRC_LE_BITS == 2 # elif CRC_LE_BITS == 2
while (len--) { while (len--) {
crc ^= *p++; crc ^= *p++;
crc = (crc >> 2) ^ crc32table_le[0][crc & 3]; crc = (crc >> 2) ^ tab[0][crc & 3];
crc = (crc >> 2) ^ crc32table_le[0][crc & 3]; crc = (crc >> 2) ^ tab[0][crc & 3];
crc = (crc >> 2) ^ crc32table_le[0][crc & 3]; crc = (crc >> 2) ^ tab[0][crc & 3];
crc = (crc >> 2) ^ crc32table_le[0][crc & 3]; crc = (crc >> 2) ^ tab[0][crc & 3];
} }
# elif CRC_LE_BITS == 4 # elif CRC_LE_BITS == 4
while (len--) { while (len--) {
crc ^= *p++; crc ^= *p++;
crc = (crc >> 4) ^ crc32table_le[0][crc & 15]; crc = (crc >> 4) ^ tab[0][crc & 15];
crc = (crc >> 4) ^ crc32table_le[0][crc & 15]; crc = (crc >> 4) ^ tab[0][crc & 15];
} }
# elif CRC_LE_BITS == 8 # elif CRC_LE_BITS == 8
/* aka Sarwate algorithm */ /* aka Sarwate algorithm */
while (len--) { while (len--) {
crc ^= *p++; crc ^= *p++;
crc = (crc >> 8) ^ crc32table_le[0][crc & 255]; crc = (crc >> 8) ^ tab[0][crc & 255];
} }
# else # else
const u32 (*tab)[] = crc32table_le;
crc = (__force u32) __cpu_to_le32(crc); crc = (__force u32) __cpu_to_le32(crc);
crc = crc32_body(crc, p, len, tab); crc = crc32_body(crc, p, len, tab);
crc = __le32_to_cpu((__force __le32)crc); crc = __le32_to_cpu((__force __le32)crc);
#endif #endif
return crc; return crc;
} }
#if CRC_LE_BITS == 1
u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len)
{
return crc32_le_generic(crc, p, len, NULL, CRCPOLY_LE);
}
u32 __pure __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 crc32_le(u32 crc, unsigned char const *p, size_t len)
{
return crc32_le_generic(crc, p, len, crc32table_le, CRCPOLY_LE);
}
u32 __pure __crc32c_le(u32 crc, unsigned char const *p, size_t len)
{
return crc32_le_generic(crc, p, len, crc32ctable_le, CRC32C_POLY_LE);
}
#endif
EXPORT_SYMBOL(crc32_le); EXPORT_SYMBOL(crc32_le);
EXPORT_SYMBOL(__crc32c_le);
/** /**
* crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32 * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32
@ -182,7 +203,9 @@ EXPORT_SYMBOL(crc32_le);
* @p: pointer to buffer over which CRC is run * @p: pointer to buffer over which CRC is run
* @len: length of buffer @p * @len: length of buffer @p
*/ */
u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len) 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 #if CRC_BE_BITS == 1
int i; int i;
@ -190,37 +213,47 @@ u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
crc ^= *p++ << 24; crc ^= *p++ << 24;
for (i = 0; i < 8; i++) for (i = 0; i < 8; i++)
crc = crc =
(crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : (crc << 1) ^ ((crc & 0x80000000) ? polynomial :
0); 0);
} }
# elif CRC_BE_BITS == 2 # elif CRC_BE_BITS == 2
while (len--) { while (len--) {
crc ^= *p++ << 24; crc ^= *p++ << 24;
crc = (crc << 2) ^ crc32table_be[0][crc >> 30]; crc = (crc << 2) ^ tab[0][crc >> 30];
crc = (crc << 2) ^ crc32table_be[0][crc >> 30]; crc = (crc << 2) ^ tab[0][crc >> 30];
crc = (crc << 2) ^ crc32table_be[0][crc >> 30]; crc = (crc << 2) ^ tab[0][crc >> 30];
crc = (crc << 2) ^ crc32table_be[0][crc >> 30]; crc = (crc << 2) ^ tab[0][crc >> 30];
} }
# elif CRC_BE_BITS == 4 # elif CRC_BE_BITS == 4
while (len--) { while (len--) {
crc ^= *p++ << 24; crc ^= *p++ << 24;
crc = (crc << 4) ^ crc32table_be[0][crc >> 28]; crc = (crc << 4) ^ tab[0][crc >> 28];
crc = (crc << 4) ^ crc32table_be[0][crc >> 28]; crc = (crc << 4) ^ tab[0][crc >> 28];
} }
# elif CRC_BE_BITS == 8 # elif CRC_BE_BITS == 8
while (len--) { while (len--) {
crc ^= *p++ << 24; crc ^= *p++ << 24;
crc = (crc << 8) ^ crc32table_be[0][crc >> 24]; crc = (crc << 8) ^ tab[0][crc >> 24];
} }
# else # else
const u32 (*tab)[] = crc32table_be;
crc = (__force u32) __cpu_to_be32(crc); crc = (__force u32) __cpu_to_be32(crc);
crc = crc32_body(crc, p, len, tab); crc = crc32_body(crc, p, len, tab);
crc = __be32_to_cpu((__force __be32)crc); crc = __be32_to_cpu((__force __be32)crc);
# endif # endif
return crc; 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, CRCPOLY_BE);
}
#else
u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
{
return crc32_be_generic(crc, p, len, crc32table_be, CRCPOLY_BE);
}
#endif
EXPORT_SYMBOL(crc32_be); EXPORT_SYMBOL(crc32_be);
#ifdef CONFIG_CRC32_SELFTEST #ifdef CONFIG_CRC32_SELFTEST

7
lib/crc32defs.h
View file

@ -6,6 +6,13 @@
#define CRCPOLY_LE 0xedb88320 #define CRCPOLY_LE 0xedb88320
#define CRCPOLY_BE 0x04c11db7 #define CRCPOLY_BE 0x04c11db7
/*
* This is the CRC32c polynomial, as outlined by Castagnoli.
* x^32+x^28+x^27+x^26+x^25+x^23+x^22+x^20+x^19+x^18+x^14+x^13+x^11+x^10+x^9+
* x^8+x^6+x^0
*/
#define CRC32C_POLY_LE 0x82F63B78
/* /*
* How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64. * How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64.
* For less performance-sensitive, use 4 or 8 to save table size. * For less performance-sensitive, use 4 or 8 to save table size.

35
lib/gen_crc32table.c
View file

@ -23,6 +23,7 @@
static uint32_t crc32table_le[LE_TABLE_ROWS][256]; static uint32_t crc32table_le[LE_TABLE_ROWS][256];
static uint32_t crc32table_be[BE_TABLE_ROWS][256]; static uint32_t crc32table_be[BE_TABLE_ROWS][256];
static uint32_t crc32ctable_le[LE_TABLE_ROWS][256];
/** /**
* crc32init_le() - allocate and initialize LE table data * crc32init_le() - allocate and initialize LE table data
@ -31,27 +32,38 @@ static uint32_t crc32table_be[BE_TABLE_ROWS][256];
* fact that crctable[i^j] = crctable[i] ^ crctable[j]. * fact that crctable[i^j] = crctable[i] ^ crctable[j].
* *
*/ */
static void crc32init_le(void) static void crc32init_le_generic(const uint32_t polynomial,
uint32_t (*tab)[256])
{ {
unsigned i, j; unsigned i, j;
uint32_t crc = 1; uint32_t crc = 1;
crc32table_le[0][0] = 0; tab[0][0] = 0;
for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) { for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) {
crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0); crc = (crc >> 1) ^ ((crc & 1) ? polynomial : 0);
for (j = 0; j < LE_TABLE_SIZE; j += 2 * i) for (j = 0; j < LE_TABLE_SIZE; j += 2 * i)
crc32table_le[0][i + j] = crc ^ crc32table_le[0][j]; tab[0][i + j] = crc ^ tab[0][j];
} }
for (i = 0; i < LE_TABLE_SIZE; i++) { for (i = 0; i < LE_TABLE_SIZE; i++) {
crc = crc32table_le[0][i]; crc = tab[0][i];
for (j = 1; j < LE_TABLE_ROWS; j++) { for (j = 1; j < LE_TABLE_ROWS; j++) {
crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8); crc = tab[0][crc & 0xff] ^ (crc >> 8);
crc32table_le[j][i] = crc; tab[j][i] = crc;
} }
} }
} }
static void crc32init_le(void)
{
crc32init_le_generic(CRCPOLY_LE, crc32table_le);
}
static void crc32cinit_le(void)
{
crc32init_le_generic(CRC32C_POLY_LE, crc32ctable_le);
}
/** /**
* crc32init_be() - allocate and initialize BE table data * crc32init_be() - allocate and initialize BE table data
*/ */
@ -114,6 +126,15 @@ int main(int argc, char** argv)
BE_TABLE_SIZE, "tobe"); BE_TABLE_SIZE, "tobe");
printf("};\n"); printf("};\n");
} }
if (CRC_LE_BITS > 1) {
crc32cinit_le();
printf("static const u32 __cacheline_aligned "
"crc32ctable_le[%d][%d] = {",
LE_TABLE_ROWS, LE_TABLE_SIZE);
output_table(crc32ctable_le, LE_TABLE_ROWS,
LE_TABLE_SIZE, "tole");
printf("};\n");
}
return 0; return 0;
} }