Messages in this thread Patch in this message | | | Date | Tue, 09 Aug 2011 00:27:59 -0500 | From | Bob Pearson <> | Subject | [patch v3 6/7] crc32: add-slicing-by-8.diff |
| |
add slicing-by-8 algorithm to the existing slicing-by-4 algorithm. This consists of:
- extend largest BITS size from 32 to 64 - extend table from tab[4][256] to tab[8][256] - change algorithm to align on 8 byte boundary (it was noted that all that is really required is that the inner loop must comsume 8 bytes. As written it can start on even or odd 4 byte boundary.) - Add code for inner loop.
Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com>
--- lib/crc32.c | 58 ++++++++++++++++++++++++++++++++++++++++++--------- lib/crc32defs.h | 14 ++++++------ lib/gen_crc32table.c | 40 +++++++++++++++++++++-------------- 3 files changed, 79 insertions(+), 33 deletions(-)
Index: infiniband/lib/crc32.c =================================================================== --- infiniband.orig/lib/crc32.c +++ infiniband/lib/crc32.c @@ -45,6 +45,7 @@ MODULE_LICENSE("GPL");
#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
+/* implements slicing-by-4 or slicing-by-8 algorithm */ static inline u32 crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256]) { @@ -54,41 +55,78 @@ crc32_body(u32 crc, unsigned char const tab[2][(crc >> 8) & 255] ^ \ tab[1][(crc >> 16) & 255] ^ \ tab[0][(crc >> 24) & 255] +# define DO_CRC8a (tab[7][(q) & 255] ^ \ + tab[6][(q >> 8) & 255] ^ \ + tab[5][(q >> 16) & 255] ^ \ + tab[4][(q >> 24) & 255]) +# define DO_CRC8b (tab[3][(q) & 255] ^ \ + tab[2][(q >> 8) & 255] ^ \ + tab[1][(q >> 16) & 255] ^ \ + tab[0][(q >> 24) & 255]) # else # define DO_CRC(x) crc = tab[0][((crc >> 24) ^ (x)) & 255] ^ (crc << 8) # define DO_CRC4 crc = tab[0][(crc) & 255] ^ \ tab[1][(crc >> 8) & 255] ^ \ tab[2][(crc >> 16) & 255] ^ \ tab[3][(crc >> 24) & 255] +# define DO_CRC8a (tab[4][(q) & 255] ^ \ + tab[5][(q >> 8) & 255] ^ \ + tab[6][(q >> 16) & 255] ^ \ + tab[8][(q >> 24) & 255]) +# define DO_CRC8b (tab[0][(q) & 255] ^ \ + tab[1][(q >> 8) & 255] ^ \ + tab[2][(q >> 16) & 255] ^ \ + tab[3][(q >> 24) & 255]) # endif const u32 *b; - size_t rem_len; + size_t init_len; + size_t middle_len; + size_t rem_len; + + /* break buf into init_len bytes before and + * rem_len bytes after a middle section with + * middle_len properly aligned words */ +# if CRC_LE_BITS == 32 + init_len = min((-((uintptr_t)buf)) & 3, len); + middle_len = (len - init_len) >> 2; + rem_len = (len - init_len) & 3; +# else + init_len = min((-((uintptr_t)buf)) & 7, len); + middle_len = (len - init_len) >> 3; + rem_len = (len - init_len) & 7; +# endif
/* Align it */ - if (unlikely((long)buf & 3 && len)) { + if (unlikely(init_len)) { do { DO_CRC(*buf++); - } while ((--len) && ((long)buf)&3); + } while (--init_len); } - rem_len = len & 3; - /* load data 32 bits wide, xor data 32 bits wide. */ - len = len >> 2; b = (const u32 *)buf; - for (--b; len; --len) { + for (--b; middle_len; --middle_len) { +# if CRC_LE_BITS == 32 crc ^= *++b; /* use pre increment for speed */ DO_CRC4; +# else + u32 q; + q = crc ^ *++b; + crc = DO_CRC8a; + q = *++b; + crc ^= DO_CRC8b; +# endif } - len = rem_len; /* And the last few bytes */ - if (len) { + if (rem_len) { u8 *p = (u8 *)(b + 1) - 1; do { DO_CRC(*++p); /* use pre increment for speed */ - } while (--len); + } while (--rem_len); } return crc; #undef DO_CRC #undef DO_CRC4 +#undef DO_CRC8a +#undef DO_CRC8b } #endif
Index: infiniband/lib/crc32defs.h =================================================================== --- infiniband.orig/lib/crc32defs.h +++ infiniband/lib/crc32defs.h @@ -6,29 +6,29 @@ #define CRCPOLY_LE 0xedb88320 #define CRCPOLY_BE 0x04c11db7
-/* How many bits at a time to use. Valid values are 1, 2, 4, 8, and 32. */ +/* 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 */ #ifndef CRC_LE_BITS -# define CRC_LE_BITS 32 +# define CRC_LE_BITS 64 #endif #ifndef CRC_BE_BITS -# define CRC_BE_BITS 32 +# define CRC_BE_BITS 64 #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 > 32 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \ +#if CRC_LE_BITS > 64 || 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}" +# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 64}" #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 > 32 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \ +#if CRC_BE_BITS > 64 || 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}" +# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 64}" #endif Index: infiniband/lib/gen_crc32table.c =================================================================== --- infiniband.orig/lib/gen_crc32table.c +++ infiniband/lib/gen_crc32table.c @@ -4,20 +4,24 @@
#define ENTRIES_PER_LINE 4
-#if CRC_LE_BITS <= 8 -#define LE_TABLE_SIZE (1 << CRC_LE_BITS) +#if CRC_LE_BITS > 8 +# define LE_TABLE_ROWS (CRC_LE_BITS/8) +# define LE_TABLE_SIZE 256 #else -#define LE_TABLE_SIZE 256 +# define LE_TABLE_ROWS 1 +# define LE_TABLE_SIZE (1 << CRC_LE_BITS) #endif
-#if CRC_BE_BITS <= 8 -#define BE_TABLE_SIZE (1 << CRC_BE_BITS) +#if CRC_BE_BITS > 8 +# define BE_TABLE_ROWS (CRC_BE_BITS/8) +# define BE_TABLE_SIZE 256 #else -#define BE_TABLE_SIZE 256 +# define BE_TABLE_ROWS 1 +# define BE_TABLE_SIZE (1 << CRC_BE_BITS) #endif
-static uint32_t crc32table_le[8][256]; -static uint32_t crc32table_be[8][256]; +static uint32_t crc32table_le[LE_TABLE_ROWS][256]; +static uint32_t crc32table_be[BE_TABLE_ROWS][256];
/** * crc32init_le() - allocate and initialize LE table data @@ -40,7 +44,7 @@ static void crc32init_le(void) } for (i = 0; i < LE_TABLE_SIZE; i++) { crc = crc32table_le[0][i]; - for (j = 1; j < 8; j++) { + for (j = 1; j < LE_TABLE_ROWS; j++) { crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8); crc32table_le[j][i] = crc; } @@ -64,18 +68,18 @@ static void crc32init_be(void) } for (i = 0; i < BE_TABLE_SIZE; i++) { crc = crc32table_be[0][i]; - for (j = 1; j < 8; j++) { + for (j = 1; j < BE_TABLE_ROWS; j++) { crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8); crc32table_be[j][i] = crc; } } }
-static void output_table(uint32_t table[8][256], int len, char *trans) +static void output_table(uint32_t (*table)[256], int rows, int len, char *trans) { int i, j;
- for (j = 0 ; j < 8; j++) { + for (j = 0 ; j < rows; j++) { printf("{"); for (i = 0; i < len - 1; i++) { if (i % ENTRIES_PER_LINE == 0) @@ -92,15 +96,19 @@ int main(int argc, char** argv)
if (CRC_LE_BITS > 1) { crc32init_le(); - printf("static const u32 crc32table_le[8][256] = {"); - output_table(crc32table_le, LE_TABLE_SIZE, "tole"); + printf("static const u32 crc32table_le[%d][%d] = {", + LE_TABLE_ROWS, LE_TABLE_SIZE); + output_table(crc32table_le, LE_TABLE_ROWS, + LE_TABLE_SIZE, "tole"); printf("};\n"); }
if (CRC_BE_BITS > 1) { crc32init_be(); - printf("static const u32 crc32table_be[8][256] = {"); - output_table(crc32table_be, BE_TABLE_SIZE, "tobe"); + printf("static const u32 crc32table_be[%d][%d] = {", + BE_TABLE_ROWS, BE_TABLE_SIZE); + output_table(crc32table_be, LE_TABLE_ROWS, + BE_TABLE_SIZE, "tobe"); printf("};\n"); }
| |