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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 <[email protected]>
Cc: Herbert Xu <[email protected]>
Cc: Bob Pearson <[email protected]>
Cc: Randy Dunlap <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
This commit is contained in:
Darrick J. Wong 2012-03-23 15:02:25 -07:00 • committed by Linus Torvalds
commit 46c5801eaf
5 changed files with 97 additions and 34 deletions
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79
lib/crc32.c
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@ -46,7 +46,7 @@
#include "crc32table.h"
MODULE_AUTHOR("Matt Domsch <[email protected]>");
MODULE_DESCRIPTION("Ethernet CRC32 calculations");
MODULE_DESCRIPTION("Various CRC32 calculations");
MODULE_LICENSE("GPL");
#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
* @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
int i;
while (len--) {
crc ^= *p++;
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
while (len--) {
crc ^= *p++;
crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
crc = (crc >> 2) ^ crc32table_le[0][crc & 3];
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) ^ crc32table_le[0][crc & 15];
crc = (crc >> 4) ^ crc32table_le[0][crc & 15];
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) ^ crc32table_le[0][crc & 255];
crc = (crc >> 8) ^ tab[0][crc & 255];
}
# else
const u32 (*tab)[] = crc32table_le;
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 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(__crc32c_le);
/**
* 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
* @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
int i;
@ -190,37 +213,47 @@ u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len)
crc ^= *p++ << 24;
for (i = 0; i < 8; i++)
crc =
(crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE :
(crc << 1) ^ ((crc & 0x80000000) ? polynomial :
0);
}
# elif CRC_BE_BITS == 2
while (len--) {
crc ^= *p++ << 24;
crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
crc = (crc << 2) ^ crc32table_be[0][crc >> 30];
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) ^ crc32table_be[0][crc >> 28];
crc = (crc << 4) ^ crc32table_be[0][crc >> 28];
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) ^ crc32table_be[0][crc >> 24];
crc = (crc << 8) ^ tab[0][crc >> 24];
}
# else
const u32 (*tab)[] = crc32table_be;
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, 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);
#ifdef CONFIG_CRC32_SELFTEST