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authorBob Pearson <rpearson@systemfabricworks.com>2012-03-24 02:02:24 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2012-03-24 03:58:37 +0400
commit324eb0f17d9dcead3c60c133aa244f6b3631fec9 (patch)
tree657c564269a0fc1921f4252dbf0184725f5c85fa /lib/crc32defs.h
parent9a1dbf6a29694c9d81b498019f103aee0f8b5b6c (diff)
downloadlinux-324eb0f17d9dcead3c60c133aa244f6b3631fec9.tar.xz
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/crc32defs.h')
-rw-r--r--lib/crc32defs.h29
1 files changed, 21 insertions, 8 deletions
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 @@
#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. */
-/* For less performance-sensitive, use 4 or 8 */
+/*
+ * 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 to save table size.
+ * For larger systems choose same as CPU architecture as default.
+ * This works well on X86_64, SPARC64 systems. This may require some
+ * elaboration after experiments with other architectures.
+ */
#ifndef CRC_LE_BITS
-# define CRC_LE_BITS 32
+# ifdef CONFIG_64BIT
+# define CRC_LE_BITS 64
+# else
+# define CRC_LE_BITS 32
+# endif
#endif
#ifndef CRC_BE_BITS
-# define CRC_BE_BITS 32
+# ifdef CONFIG_64BIT
+# define CRC_BE_BITS 64
+# else
+# define CRC_BE_BITS 32
+# endif
#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, 32, 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, 32, 64}"
#endif