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Date: Tue, 09 Aug 2011 00:25:49 -0500 From: Bob Pearson <rpearson@...temfabricworks.com> To: linux-kernel@...r.kernel.org, linux@...izon.com, joakim.tjernlund@...nsmode.se, fzago@...temfabricworks.com, rpearson@...temfabricworks.com, akpm@...ux-foundation.org Subject: [patch v3 5/7] crc32: add-real-8-bit.diff 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@...temfabricworks.com> --- lib/crc32.c | 17 ++++++++++++++--- lib/crc32defs.h | 18 ++++++++++-------- lib/gen_crc32table.c | 27 ++++++++++++++++++--------- 3 files changed, 42 insertions(+), 20 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]) @@ -123,6 +123,12 @@ 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); @@ -166,6 +172,11 @@ 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[8][256]; +static uint32_t crc32table_be[8][256]; /** * crc32init_le() - allocate and initialize LE table data @@ -24,14 +33,14 @@ 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]; } for (i = 0; i < LE_TABLE_SIZE; i++) { crc = crc32table_le[0][i]; - for (j = 1; j < 4; j++) { + for (j = 1; j < 8; j++) { crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8); crc32table_le[j][i] = crc; } @@ -55,18 +64,18 @@ static void crc32init_be(void) } for (i = 0; i < BE_TABLE_SIZE; i++) { crc = crc32table_be[0][i]; - for (j = 1; j < 4; j++) { + for (j = 1; j < 8; j++) { crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8); crc32table_be[j][i] = crc; } } } -static void output_table(uint32_t table[4][256], int len, char *trans) +static void output_table(uint32_t table[8][256], int len, char *trans) { int i, j; - for (j = 0 ; j < 4; j++) { + for (j = 0 ; j < 8; j++) { printf("{"); for (i = 0; i < len - 1; i++) { if (i % ENTRIES_PER_LINE == 0) @@ -83,14 +92,14 @@ int main(int argc, char** argv) if (CRC_LE_BITS > 1) { crc32init_le(); - printf("static const u32 crc32table_le[4][256] = {"); + printf("static const u32 crc32table_le[8][256] = {"); output_table(crc32table_le, LE_TABLE_SIZE, "tole"); printf("};\n"); } if (CRC_BE_BITS > 1) { crc32init_be(); - printf("static const u32 crc32table_be[4][256] = {"); + printf("static const u32 crc32table_be[8][256] = {"); output_table(crc32table_be, BE_TABLE_SIZE, "tobe"); printf("};\n"); } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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