Messages in this thread Patch in this message | | | Date | Thu, 11 Aug 2011 12:43:17 -0500 | From | Bob Pearson <> | Subject | [patches v5 resending 6/8] crc32: add-real-8-bit.diff |
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crc32.c encodes an algorithm that processes 32 bits at a time with the value BITS = 8 and leaves out the most common 8 bit algorithm for computing the crc. This patch reencodes the 32 bit algorithm with the value 32 and adds back the 'standard' 8 bit algorithm.
Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com>
--- lib/crc32.c | 17 ++++++++++++++--- lib/crc32defs.h | 18 ++++++++++-------- lib/gen_crc32table.c | 15 ++++++++++++--- 3 files changed, 36 insertions(+), 14 deletions(-)
Index: infiniband/lib/crc32.c =================================================================== --- infiniband.orig/lib/crc32.c +++ infiniband/lib/crc32.c @@ -25,13 +25,13 @@ #include <linux/types.h> #include "crc32defs.h"
-#if CRC_LE_BITS == 8 +#if CRC_LE_BITS > 8 # define tole(x) (__force u32) __constant_cpu_to_le32(x) #else # define tole(x) (x) #endif
-#if CRC_BE_BITS == 8 +#if CRC_BE_BITS > 8 # define tobe(x) (__force u32) __constant_cpu_to_be32(x) #else # define tobe(x) (x) @@ -43,7 +43,7 @@ MODULE_AUTHOR("Matt Domsch <Matt_Domsch@ MODULE_DESCRIPTION("Ethernet CRC32 calculations"); MODULE_LICENSE("GPL");
-#if CRC_LE_BITS == 8 || CRC_BE_BITS == 8 +#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
static inline u32 crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256]) @@ -124,6 +124,12 @@ u32 __pure crc32_le(u32 crc, unsigned ch crc = (crc >> 4) ^ crc32table_le[0][crc & 15]; } # elif CRC_LE_BITS == 8 + /* aka Sarwate algorithm */ + while (len--) { + crc ^= *p++; + crc = (crc >> 8) ^ crc32table_le[0][crc & 255]; + } +# else const u32 (*tab)[] = crc32table_le;
crc = (__force u32) __cpu_to_le32(crc); @@ -167,6 +173,11 @@ u32 __pure crc32_be(u32 crc, unsigned ch crc = (crc << 4) ^ crc32table_be[0][crc >> 28]; } # elif CRC_BE_BITS == 8 + while (len--) { + crc ^= *p++ << 24; + crc = (crc << 8) ^ crc32table_be[0][crc >> 24]; + } +# else const u32 (*tab)[] = crc32table_be;
crc = (__force u32) __cpu_to_be32(crc); Index: infiniband/lib/crc32defs.h =================================================================== --- infiniband.orig/lib/crc32defs.h +++ infiniband/lib/crc32defs.h @@ -6,27 +6,29 @@ #define CRCPOLY_LE 0xedb88320 #define CRCPOLY_BE 0x04c11db7
-/* How many bits at a time to use. Requires a table of 4<<CRC_xx_BITS bytes. */ -/* For less performance-sensitive, use 4 */ +/* How many bits at a time to use. Valid values are 1, 2, 4, 8, and 32. */ +/* For less performance-sensitive, use 4 or 8 */ #ifndef CRC_LE_BITS -# define CRC_LE_BITS 8 +# define CRC_LE_BITS 32 #endif #ifndef CRC_BE_BITS -# define CRC_BE_BITS 8 +# define CRC_BE_BITS 32 #endif
/* * Little-endian CRC computation. Used with serial bit streams sent * lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC. */ -#if CRC_LE_BITS > 8 || CRC_LE_BITS < 1 || CRC_LE_BITS & CRC_LE_BITS-1 -# error CRC_LE_BITS must be a power of 2 between 1 and 8 +#if CRC_LE_BITS > 32 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \ + CRC_LE_BITS & CRC_LE_BITS-1 +# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32}" #endif
/* * Big-endian CRC computation. Used with serial bit streams sent * msbit-first. Be sure to use cpu_to_be32() to append the computed CRC. */ -#if CRC_BE_BITS > 8 || CRC_BE_BITS < 1 || CRC_BE_BITS & CRC_BE_BITS-1 -# error CRC_BE_BITS must be a power of 2 between 1 and 8 +#if CRC_BE_BITS > 32 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \ + CRC_BE_BITS & CRC_BE_BITS-1 +# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32}" #endif Index: infiniband/lib/gen_crc32table.c =================================================================== --- infiniband.orig/lib/gen_crc32table.c +++ infiniband/lib/gen_crc32table.c @@ -4,11 +4,20 @@
#define ENTRIES_PER_LINE 4
+#if CRC_LE_BITS <= 8 #define LE_TABLE_SIZE (1 << CRC_LE_BITS) +#else +#define LE_TABLE_SIZE 256 +#endif + +#if CRC_BE_BITS <= 8 #define BE_TABLE_SIZE (1 << CRC_BE_BITS) +#else +#define BE_TABLE_SIZE 256 +#endif
-static uint32_t crc32table_le[4][LE_TABLE_SIZE]; -static uint32_t crc32table_be[4][BE_TABLE_SIZE]; +static uint32_t crc32table_le[4][256]; +static uint32_t crc32table_be[4][256];
/** * crc32init_le() - allocate and initialize LE table data @@ -24,7 +33,7 @@ static void crc32init_le(void)
crc32table_le[0][0] = 0;
- for (i = 1 << (CRC_LE_BITS - 1); i; i >>= 1) { + for (i = LE_TABLE_SIZE >> 1; i; i >>= 1) { crc = (crc >> 1) ^ ((crc & 1) ? CRCPOLY_LE : 0); for (j = 0; j < LE_TABLE_SIZE; j += 2 * i) crc32table_le[0][i + j] = crc ^ crc32table_le[0][j];
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