crc32: add slice-by-8 algorithm to existing code
Add slicing-by-8 algorithm to the existing slicing-by-4 algorithm. This consists of: - extend largest BITS size from 32 to 64 - extend tables from tab[4][256] to up to tab[8][256] - Add code for inner loop. [djwong@us.ibm.com: Minor changelog tweaks] Signed-off-by: Bob Pearson <rpearson@systemfabricworks.com> Signed-off-by: Darrick J. Wong <djwong@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Bob Pearson
Linus Torvalds
Родитель
9a1dbf6a29
Коммит
324eb0f17d
38
lib/crc32.c
38
lib/crc32.c
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@ -47,25 +47,28 @@ MODULE_LICENSE("GPL");
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#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
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/* implements slicing-by-4 or slicing-by-8 algorithm */
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static inline u32
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crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
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{
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# ifdef __LITTLE_ENDIAN
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# define DO_CRC(x) crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8)
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# define DO_CRC4 crc = t3[(crc) & 255] ^ \
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t2[(crc >> 8) & 255] ^ \
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t1[(crc >> 16) & 255] ^ \
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t0[(crc >> 24) & 255]
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# define DO_CRC4 (t3[(q) & 255] ^ t2[(q >> 8) & 255] ^ \
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t1[(q >> 16) & 255] ^ t0[(q >> 24) & 255])
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# define DO_CRC8 (t7[(q) & 255] ^ t6[(q >> 8) & 255] ^ \
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t5[(q >> 16) & 255] ^ t4[(q >> 24) & 255])
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# else
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# define DO_CRC(x) crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
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# define DO_CRC4 crc = t0[(crc) & 255] ^ \
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t1[(crc >> 8) & 255] ^ \
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t2[(crc >> 16) & 255] ^ \
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t3[(crc >> 24) & 255]
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# define DO_CRC4 (t0[(q) & 255] ^ t1[(q >> 8) & 255] ^ \
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t2[(q >> 16) & 255] ^ t3[(q >> 24) & 255])
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# define DO_CRC8 (t4[(q) & 255] ^ t5[(q >> 8) & 255] ^ \
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t6[(q >> 16) & 255] ^ t7[(q >> 24) & 255])
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# endif
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const u32 *b;
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size_t rem_len;
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const u32 *t0=tab[0], *t1=tab[1], *t2=tab[2], *t3=tab[3];
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const u32 *t4 = tab[4], *t5 = tab[5], *t6 = tab[6], *t7 = tab[7];
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u32 q;
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/* Align it */
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if (unlikely((long)buf & 3 && len)) {
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@ -73,13 +76,25 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
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DO_CRC(*buf++);
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} while ((--len) && ((long)buf)&3);
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}
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# if CRC_LE_BITS == 32
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rem_len = len & 3;
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/* load data 32 bits wide, xor data 32 bits wide. */
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len = len >> 2;
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# else
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rem_len = len & 7;
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len = len >> 3;
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# endif
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b = (const u32 *)buf;
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for (--b; len; --len) {
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crc ^= *++b; /* use pre increment for speed */
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DO_CRC4;
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q = crc ^ *++b; /* use pre increment for speed */
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# if CRC_LE_BITS == 32
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crc = DO_CRC4;
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# else
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crc = DO_CRC8;
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q = *++b;
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crc ^= DO_CRC4;
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# endif
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}
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len = rem_len;
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/* And the last few bytes */
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@ -92,6 +107,7 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
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return crc;
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#undef DO_CRC
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#undef DO_CRC4
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#undef DO_CRC8
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}
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#endif
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@ -6,29 +6,42 @@
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#define CRCPOLY_LE 0xedb88320
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#define CRCPOLY_BE 0x04c11db7
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/* How many bits at a time to use. Valid values are 1, 2, 4, 8, and 32. */
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/* For less performance-sensitive, use 4 or 8 */
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/*
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* How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64.
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* For less performance-sensitive, use 4 or 8 to save table size.
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* For larger systems choose same as CPU architecture as default.
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* This works well on X86_64, SPARC64 systems. This may require some
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* elaboration after experiments with other architectures.
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*/
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#ifndef CRC_LE_BITS
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# define CRC_LE_BITS 32
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# ifdef CONFIG_64BIT
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# define CRC_LE_BITS 64
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# else
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# define CRC_LE_BITS 32
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# endif
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#endif
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#ifndef CRC_BE_BITS
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# define CRC_BE_BITS 32
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# ifdef CONFIG_64BIT
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# define CRC_BE_BITS 64
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# else
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# define CRC_BE_BITS 32
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# endif
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#endif
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/*
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* Little-endian CRC computation. Used with serial bit streams sent
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* lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC.
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*/
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#if CRC_LE_BITS > 32 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
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#if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
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CRC_LE_BITS & CRC_LE_BITS-1
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# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32}"
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# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32, 64}"
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#endif
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/*
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* Big-endian CRC computation. Used with serial bit streams sent
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* msbit-first. Be sure to use cpu_to_be32() to append the computed CRC.
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*/
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#if CRC_BE_BITS > 32 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
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#if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
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CRC_BE_BITS & CRC_BE_BITS-1
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# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32}"
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# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32, 64}"
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#endif
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@ -1,23 +1,28 @@
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#include <stdio.h>
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#include "../include/generated/autoconf.h"
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#include "crc32defs.h"
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#include <inttypes.h>
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#define ENTRIES_PER_LINE 4
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#if CRC_LE_BITS <= 8
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#define LE_TABLE_SIZE (1 << CRC_LE_BITS)
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#if CRC_LE_BITS > 8
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# define LE_TABLE_ROWS (CRC_LE_BITS/8)
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# define LE_TABLE_SIZE 256
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#else
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#define LE_TABLE_SIZE 256
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# define LE_TABLE_ROWS 1
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# define LE_TABLE_SIZE (1 << CRC_LE_BITS)
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#endif
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#if CRC_BE_BITS <= 8
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#define BE_TABLE_SIZE (1 << CRC_BE_BITS)
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#if CRC_BE_BITS > 8
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# define BE_TABLE_ROWS (CRC_BE_BITS/8)
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# define BE_TABLE_SIZE 256
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#else
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#define BE_TABLE_SIZE 256
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# define BE_TABLE_ROWS 1
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# define BE_TABLE_SIZE (1 << CRC_BE_BITS)
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#endif
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static uint32_t crc32table_le[4][256];
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static uint32_t crc32table_be[4][256];
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static uint32_t crc32table_le[LE_TABLE_ROWS][256];
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static uint32_t crc32table_be[BE_TABLE_ROWS][256];
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/**
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* crc32init_le() - allocate and initialize LE table data
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@ -40,7 +45,7 @@ static void crc32init_le(void)
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}
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for (i = 0; i < LE_TABLE_SIZE; i++) {
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crc = crc32table_le[0][i];
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for (j = 1; j < 4; j++) {
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for (j = 1; j < LE_TABLE_ROWS; j++) {
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crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8);
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crc32table_le[j][i] = crc;
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}
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@ -64,18 +69,18 @@ static void crc32init_be(void)
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}
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for (i = 0; i < BE_TABLE_SIZE; i++) {
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crc = crc32table_be[0][i];
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for (j = 1; j < 4; j++) {
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for (j = 1; j < BE_TABLE_ROWS; j++) {
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crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8);
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crc32table_be[j][i] = crc;
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}
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}
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}
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static void output_table(uint32_t (*table)[256], int len, char *trans)
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static void output_table(uint32_t (*table)[256], int rows, int len, char *trans)
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{
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int i, j;
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for (j = 0 ; j < 4; j++) {
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for (j = 0 ; j < rows; j++) {
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printf("{");
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for (i = 0; i < len - 1; i++) {
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if (i % ENTRIES_PER_LINE == 0)
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@ -92,15 +97,21 @@ int main(int argc, char** argv)
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if (CRC_LE_BITS > 1) {
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crc32init_le();
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printf("static const u32 crc32table_le[4][256] = {");
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output_table(crc32table_le, LE_TABLE_SIZE, "tole");
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printf("static const u32 __cacheline_aligned "
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"crc32table_le[%d][%d] = {",
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LE_TABLE_ROWS, LE_TABLE_SIZE);
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output_table(crc32table_le, LE_TABLE_ROWS,
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LE_TABLE_SIZE, "tole");
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printf("};\n");
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}
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if (CRC_BE_BITS > 1) {
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crc32init_be();
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printf("static const u32 crc32table_be[4][256] = {");
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output_table(crc32table_be, BE_TABLE_SIZE, "tobe");
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printf("static const u32 __cacheline_aligned "
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"crc32table_be[%d][%d] = {",
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BE_TABLE_ROWS, BE_TABLE_SIZE);
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output_table(crc32table_be, LE_TABLE_ROWS,
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BE_TABLE_SIZE, "tobe");
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printf("};\n");
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}
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