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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 15:20:36 -0700 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /lib/crc32defs.h | |
download | lwn-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.gz lwn-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'lib/crc32defs.h')
-rw-r--r-- | lib/crc32defs.h | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/lib/crc32defs.h b/lib/crc32defs.h new file mode 100644 index 000000000000..9b6773d73749 --- /dev/null +++ b/lib/crc32defs.h @@ -0,0 +1,32 @@ +/* + * There are multiple 16-bit CRC polynomials in common use, but this is + * *the* standard CRC-32 polynomial, first popularized by Ethernet. + * x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x^1+x^0 + */ +#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 */ +#ifndef CRC_LE_BITS +# define CRC_LE_BITS 8 +#endif +#ifndef CRC_BE_BITS +# define CRC_BE_BITS 8 +#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 +#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 +#endif |