diff options
Diffstat (limited to 'lib/crc32.c')
| -rw-r--r-- | lib/crc32.c | 104 |
1 files changed, 36 insertions, 68 deletions
diff --git a/lib/crc32.c b/lib/crc32.c index 996115d4f37..bf03922c5d6 100644 --- a/lib/crc32.c +++ b/lib/crc32.c @@ -23,13 +23,10 @@ /* see: Documentation/crc32.txt for a description of algorithms */ #include <linux/crc32.h> -#include <linux/kernel.h> #include <linux/module.h> -#include <linux/compiler.h> #include <linux/types.h> -#include <linux/init.h> -#include <linux/atomic.h> #include "crc32defs.h" + #if CRC_LE_BITS == 8 # define tole(x) __constant_cpu_to_le32(x) #else @@ -41,6 +38,7 @@ #else # define tobe(x) (x) #endif + #include "crc32table.h" MODULE_AUTHOR("Matt Domsch <Matt_Domsch@dell.com>"); @@ -96,6 +94,7 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256]) #undef DO_CRC4 } #endif + /** * crc32_le() - Calculate bitwise little-endian Ethernet AUTODIN II CRC32 * @crc: seed value for computation. ~0 for Ethernet, sometimes 0 for @@ -103,53 +102,39 @@ 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); - -#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 __pure crc32_le(u32 crc, unsigned char const *p, size_t len) { +#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); } - return crc; -} -#else /* Table-based approach */ - -u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len) -{ -# if CRC_LE_BITS == 8 - const u32 (*tab)[] = crc32table_le; - - crc = __cpu_to_le32(crc); - crc = crc32_body(crc, p, len, tab); - return __le32_to_cpu(crc); -# elif CRC_LE_BITS == 4 +# elif CRC_LE_BITS == 2 while (len--) { crc ^= *p++; - crc = (crc >> 4) ^ crc32table_le[crc & 15]; - crc = (crc >> 4) ^ crc32table_le[crc & 15]; + 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]; } - return crc; -# elif CRC_LE_BITS == 2 +# elif CRC_LE_BITS == 4 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]; + crc = (crc >> 4) ^ crc32table_le[0][crc & 15]; + crc = (crc >> 4) ^ crc32table_le[0][crc & 15]; } +# elif CRC_LE_BITS == 8 + const u32 (*tab)[] = crc32table_le; + + crc = __cpu_to_le32(crc); + crc = crc32_body(crc, p, len, tab); + crc = __le32_to_cpu(crc); +#endif return crc; -# endif } -#endif +EXPORT_SYMBOL(crc32_le); /** * crc32_be() - Calculate bitwise big-endian Ethernet AUTODIN II CRC32 @@ -158,16 +143,9 @@ u32 __pure crc32_le(u32 crc, unsigned char const *p, size_t len) * @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); - -#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 __pure crc32_be(u32 crc, unsigned char const *p, size_t len) { +#if CRC_BE_BITS == 1 int i; while (len--) { crc ^= *p++ << 24; @@ -176,39 +154,29 @@ u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len) (crc << 1) ^ ((crc & 0x80000000) ? CRCPOLY_BE : 0); } - return crc; -} - -#else /* Table-based approach */ -u32 __pure crc32_be(u32 crc, unsigned char const *p, size_t len) -{ -# if CRC_BE_BITS == 8 - const u32 (*tab)[] = crc32table_be; - - crc = __cpu_to_be32(crc); - crc = crc32_body(crc, p, len, tab); - return __be32_to_cpu(crc); -# elif CRC_BE_BITS == 4 +# elif CRC_BE_BITS == 2 while (len--) { crc ^= *p++ << 24; - crc = (crc << 4) ^ crc32table_be[crc >> 28]; - crc = (crc << 4) ^ crc32table_be[crc >> 28]; + 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]; } - return crc; -# elif CRC_BE_BITS == 2 +# elif CRC_BE_BITS == 4 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]; + crc = (crc << 4) ^ crc32table_be[0][crc >> 28]; + crc = (crc << 4) ^ crc32table_be[0][crc >> 28]; } - return crc; +# elif CRC_BE_BITS == 8 + const u32 (*tab)[] = crc32table_be; + + crc = __cpu_to_be32(crc); + crc = crc32_body(crc, p, len, tab); + crc = __be32_to_cpu(crc); # endif + return crc; } -#endif - -EXPORT_SYMBOL(crc32_le); EXPORT_SYMBOL(crc32_be); #ifdef CONFIG_CRC32_SELFTEST |