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authorBob Pearson <rpearson@systemfabricworks.com>2012-03-23 18:02:24 -0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-23 19:58:37 -0400
commit324eb0f17d9dcead3c60c133aa244f6b3631fec9 (patch)
tree657c564269a0fc1921f4252dbf0184725f5c85fa /lib
parent9a1dbf6a29694c9d81b498019f103aee0f8b5b6c (diff)
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>
Diffstat (limited to 'lib')
-rw-r--r--lib/crc32.c38
-rw-r--r--lib/crc32defs.h29
-rw-r--r--lib/gen_crc32table.c43
3 files changed, 75 insertions, 35 deletions
diff --git a/lib/crc32.c b/lib/crc32.c
index 5971f2ad46d5..826e16352e0e 100644
--- a/lib/crc32.c
+++ b/lib/crc32.c
@@ -47,25 +47,28 @@ MODULE_LICENSE("GPL");
47 47
48#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8 48#if CRC_LE_BITS > 8 || CRC_BE_BITS > 8
49 49
50/* implements slicing-by-4 or slicing-by-8 algorithm */
50static inline u32 51static inline u32
51crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256]) 52crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
52{ 53{
53# ifdef __LITTLE_ENDIAN 54# ifdef __LITTLE_ENDIAN
54# define DO_CRC(x) crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8) 55# define DO_CRC(x) crc = t0[(crc ^ (x)) & 255] ^ (crc >> 8)
55# define DO_CRC4 crc = t3[(crc) & 255] ^ \ 56# define DO_CRC4 (t3[(q) & 255] ^ t2[(q >> 8) & 255] ^ \
56 t2[(crc >> 8) & 255] ^ \ 57 t1[(q >> 16) & 255] ^ t0[(q >> 24) & 255])
57 t1[(crc >> 16) & 255] ^ \ 58# define DO_CRC8 (t7[(q) & 255] ^ t6[(q >> 8) & 255] ^ \
58 t0[(crc >> 24) & 255] 59 t5[(q >> 16) & 255] ^ t4[(q >> 24) & 255])
59# else 60# else
60# define DO_CRC(x) crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8) 61# define DO_CRC(x) crc = t0[((crc >> 24) ^ (x)) & 255] ^ (crc << 8)
61# define DO_CRC4 crc = t0[(crc) & 255] ^ \ 62# define DO_CRC4 (t0[(q) & 255] ^ t1[(q >> 8) & 255] ^ \
62 t1[(crc >> 8) & 255] ^ \ 63 t2[(q >> 16) & 255] ^ t3[(q >> 24) & 255])
63 t2[(crc >> 16) & 255] ^ \ 64# define DO_CRC8 (t4[(q) & 255] ^ t5[(q >> 8) & 255] ^ \
64 t3[(crc >> 24) & 255] 65 t6[(q >> 16) & 255] ^ t7[(q >> 24) & 255])
65# endif 66# endif
66 const u32 *b; 67 const u32 *b;
67 size_t rem_len; 68 size_t rem_len;
68 const u32 *t0=tab[0], *t1=tab[1], *t2=tab[2], *t3=tab[3]; 69 const u32 *t0=tab[0], *t1=tab[1], *t2=tab[2], *t3=tab[3];
70 const u32 *t4 = tab[4], *t5 = tab[5], *t6 = tab[6], *t7 = tab[7];
71 u32 q;
69 72
70 /* Align it */ 73 /* Align it */
71 if (unlikely((long)buf & 3 && len)) { 74 if (unlikely((long)buf & 3 && len)) {
@@ -73,13 +76,25 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
73 DO_CRC(*buf++); 76 DO_CRC(*buf++);
74 } while ((--len) && ((long)buf)&3); 77 } while ((--len) && ((long)buf)&3);
75 } 78 }
79
80# if CRC_LE_BITS == 32
76 rem_len = len & 3; 81 rem_len = len & 3;
77 /* load data 32 bits wide, xor data 32 bits wide. */
78 len = len >> 2; 82 len = len >> 2;
83# else
84 rem_len = len & 7;
85 len = len >> 3;
86# endif
87
79 b = (const u32 *)buf; 88 b = (const u32 *)buf;
80 for (--b; len; --len) { 89 for (--b; len; --len) {
81 crc ^= *++b; /* use pre increment for speed */ 90 q = crc ^ *++b; /* use pre increment for speed */
82 DO_CRC4; 91# if CRC_LE_BITS == 32
92 crc = DO_CRC4;
93# else
94 crc = DO_CRC8;
95 q = *++b;
96 crc ^= DO_CRC4;
97# endif
83 } 98 }
84 len = rem_len; 99 len = rem_len;
85 /* And the last few bytes */ 100 /* And the last few bytes */
@@ -92,6 +107,7 @@ crc32_body(u32 crc, unsigned char const *buf, size_t len, const u32 (*tab)[256])
92 return crc; 107 return crc;
93#undef DO_CRC 108#undef DO_CRC
94#undef DO_CRC4 109#undef DO_CRC4
110#undef DO_CRC8
95} 111}
96#endif 112#endif
97 113
diff --git a/lib/crc32defs.h b/lib/crc32defs.h
index daa3a5e85f60..818159288489 100644
--- a/lib/crc32defs.h
+++ b/lib/crc32defs.h
@@ -6,29 +6,42 @@
6#define CRCPOLY_LE 0xedb88320 6#define CRCPOLY_LE 0xedb88320
7#define CRCPOLY_BE 0x04c11db7 7#define CRCPOLY_BE 0x04c11db7
8 8
9/* How many bits at a time to use. Valid values are 1, 2, 4, 8, and 32. */ 9/*
10/* For less performance-sensitive, use 4 or 8 */ 10 * How many bits at a time to use. Valid values are 1, 2, 4, 8, 32 and 64.
11 * For less performance-sensitive, use 4 or 8 to save table size.
12 * For larger systems choose same as CPU architecture as default.
13 * This works well on X86_64, SPARC64 systems. This may require some
14 * elaboration after experiments with other architectures.
15 */
11#ifndef CRC_LE_BITS 16#ifndef CRC_LE_BITS
12# define CRC_LE_BITS 32 17# ifdef CONFIG_64BIT
18# define CRC_LE_BITS 64
19# else
20# define CRC_LE_BITS 32
21# endif
13#endif 22#endif
14#ifndef CRC_BE_BITS 23#ifndef CRC_BE_BITS
15# define CRC_BE_BITS 32 24# ifdef CONFIG_64BIT
25# define CRC_BE_BITS 64
26# else
27# define CRC_BE_BITS 32
28# endif
16#endif 29#endif
17 30
18/* 31/*
19 * Little-endian CRC computation. Used with serial bit streams sent 32 * Little-endian CRC computation. Used with serial bit streams sent
20 * lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC. 33 * lsbit-first. Be sure to use cpu_to_le32() to append the computed CRC.
21 */ 34 */
22#if CRC_LE_BITS > 32 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \ 35#if CRC_LE_BITS > 64 || CRC_LE_BITS < 1 || CRC_LE_BITS == 16 || \
23 CRC_LE_BITS & CRC_LE_BITS-1 36 CRC_LE_BITS & CRC_LE_BITS-1
24# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32}" 37# error "CRC_LE_BITS must be one of {1, 2, 4, 8, 32, 64}"
25#endif 38#endif
26 39
27/* 40/*
28 * Big-endian CRC computation. Used with serial bit streams sent 41 * Big-endian CRC computation. Used with serial bit streams sent
29 * msbit-first. Be sure to use cpu_to_be32() to append the computed CRC. 42 * msbit-first. Be sure to use cpu_to_be32() to append the computed CRC.
30 */ 43 */
31#if CRC_BE_BITS > 32 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \ 44#if CRC_BE_BITS > 64 || CRC_BE_BITS < 1 || CRC_BE_BITS == 16 || \
32 CRC_BE_BITS & CRC_BE_BITS-1 45 CRC_BE_BITS & CRC_BE_BITS-1
33# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32}" 46# error "CRC_BE_BITS must be one of {1, 2, 4, 8, 32, 64}"
34#endif 47#endif
diff --git a/lib/gen_crc32table.c b/lib/gen_crc32table.c
index 99ac744848fb..0d9edd17ee13 100644
--- a/lib/gen_crc32table.c
+++ b/lib/gen_crc32table.c
@@ -1,23 +1,28 @@
1#include <stdio.h> 1#include <stdio.h>
2#include "../include/generated/autoconf.h"
2#include "crc32defs.h" 3#include "crc32defs.h"
3#include <inttypes.h> 4#include <inttypes.h>
4 5
5#define ENTRIES_PER_LINE 4 6#define ENTRIES_PER_LINE 4
6 7
7#if CRC_LE_BITS <= 8 8#if CRC_LE_BITS > 8
8#define LE_TABLE_SIZE (1 << CRC_LE_BITS) 9# define LE_TABLE_ROWS (CRC_LE_BITS/8)
10# define LE_TABLE_SIZE 256
9#else 11#else
10#define LE_TABLE_SIZE 256 12# define LE_TABLE_ROWS 1
13# define LE_TABLE_SIZE (1 << CRC_LE_BITS)
11#endif 14#endif
12 15
13#if CRC_BE_BITS <= 8 16#if CRC_BE_BITS > 8
14#define BE_TABLE_SIZE (1 << CRC_BE_BITS) 17# define BE_TABLE_ROWS (CRC_BE_BITS/8)
18# define BE_TABLE_SIZE 256
15#else 19#else
16#define BE_TABLE_SIZE 256 20# define BE_TABLE_ROWS 1
21# define BE_TABLE_SIZE (1 << CRC_BE_BITS)
17#endif 22#endif
18 23
19static uint32_t crc32table_le[4][256]; 24static uint32_t crc32table_le[LE_TABLE_ROWS][256];
20static uint32_t crc32table_be[4][256]; 25static uint32_t crc32table_be[BE_TABLE_ROWS][256];
21 26
22/** 27/**
23 * crc32init_le() - allocate and initialize LE table data 28 * crc32init_le() - allocate and initialize LE table data
@@ -40,7 +45,7 @@ static void crc32init_le(void)
40 } 45 }
41 for (i = 0; i < LE_TABLE_SIZE; i++) { 46 for (i = 0; i < LE_TABLE_SIZE; i++) {
42 crc = crc32table_le[0][i]; 47 crc = crc32table_le[0][i];
43 for (j = 1; j < 4; j++) { 48 for (j = 1; j < LE_TABLE_ROWS; j++) {
44 crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8); 49 crc = crc32table_le[0][crc & 0xff] ^ (crc >> 8);
45 crc32table_le[j][i] = crc; 50 crc32table_le[j][i] = crc;
46 } 51 }
@@ -64,18 +69,18 @@ static void crc32init_be(void)
64 } 69 }
65 for (i = 0; i < BE_TABLE_SIZE; i++) { 70 for (i = 0; i < BE_TABLE_SIZE; i++) {
66 crc = crc32table_be[0][i]; 71 crc = crc32table_be[0][i];
67 for (j = 1; j < 4; j++) { 72 for (j = 1; j < BE_TABLE_ROWS; j++) {
68 crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8); 73 crc = crc32table_be[0][(crc >> 24) & 0xff] ^ (crc << 8);
69 crc32table_be[j][i] = crc; 74 crc32table_be[j][i] = crc;
70 } 75 }
71 } 76 }
72} 77}
73 78
74static void output_table(uint32_t (*table)[256], int len, char *trans) 79static void output_table(uint32_t (*table)[256], int rows, int len, char *trans)
75{ 80{
76 int i, j; 81 int i, j;
77 82
78 for (j = 0 ; j < 4; j++) { 83 for (j = 0 ; j < rows; j++) {
79 printf("{"); 84 printf("{");
80 for (i = 0; i < len - 1; i++) { 85 for (i = 0; i < len - 1; i++) {
81 if (i % ENTRIES_PER_LINE == 0) 86 if (i % ENTRIES_PER_LINE == 0)
@@ -92,15 +97,21 @@ int main(int argc, char** argv)
92 97
93 if (CRC_LE_BITS > 1) { 98 if (CRC_LE_BITS > 1) {
94 crc32init_le(); 99 crc32init_le();
95 printf("static const u32 crc32table_le[4][256] = {"); 100 printf("static const u32 __cacheline_aligned "
96 output_table(crc32table_le, LE_TABLE_SIZE, "tole"); 101 "crc32table_le[%d][%d] = {",
102 LE_TABLE_ROWS, LE_TABLE_SIZE);
103 output_table(crc32table_le, LE_TABLE_ROWS,
104 LE_TABLE_SIZE, "tole");
97 printf("};\n"); 105 printf("};\n");
98 } 106 }
99 107
100 if (CRC_BE_BITS > 1) { 108 if (CRC_BE_BITS > 1) {
101 crc32init_be(); 109 crc32init_be();
102 printf("static const u32 crc32table_be[4][256] = {"); 110 printf("static const u32 __cacheline_aligned "
103 output_table(crc32table_be, BE_TABLE_SIZE, "tobe"); 111 "crc32table_be[%d][%d] = {",
112 BE_TABLE_ROWS, BE_TABLE_SIZE);
113 output_table(crc32table_be, LE_TABLE_ROWS,
114 BE_TABLE_SIZE, "tobe");
104 printf("};\n"); 115 printf("};\n");
105 } 116 }
106 117