diff options
Diffstat (limited to 'contrib/libarchive/libarchive/archive_crc32.h')
| -rw-r--r-- | contrib/libarchive/libarchive/archive_crc32.h | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/contrib/libarchive/libarchive/archive_crc32.h b/contrib/libarchive/libarchive/archive_crc32.h index 771575476d98..0a947077056e 100644 --- a/contrib/libarchive/libarchive/archive_crc32.h +++ b/contrib/libarchive/libarchive/archive_crc32.h @@ -60,6 +60,18 @@ crc32(unsigned long crc, const void *_p, size_t len) } crc = crc ^ 0xffffffffUL; + /* A use of this loop is about 20% - 30% faster than + * no use version in any optimization option of gcc. */ + for (;len >= 8; len -= 8) { + crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); + crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); + crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); + crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); + crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); + crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); + crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); + crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); + } while (len--) crc = crc_tbl[(crc ^ *p++) & 0xff] ^ (crc >> 8); return (crc ^ 0xffffffffUL); |