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Diffstat (limited to 'lib/util/xxhash.c')
| -rw-r--r-- | lib/util/xxhash.c | 103 |
1 files changed, 103 insertions, 0 deletions
diff --git a/lib/util/xxhash.c b/lib/util/xxhash.c new file mode 100644 index 0000000..4e1e0e0 --- /dev/null +++ b/lib/util/xxhash.c @@ -0,0 +1,103 @@ +/* + * xxHash - Extremely Fast Hash algorithm + * Copyright (C) 2012-2016, Yann Collet. + * + * BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php) + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions are + * met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * * Redistributions in binary form must reproduce the above + * copyright notice, this list of conditions and the following disclaimer + * in the documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT + * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, + * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT + * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE + * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * ---------------------------------------------------------------------------- + * This code has been lifted from Linux (the OS kernel) and adapted for use in + * libsquashfs. For the original, unmodified and complete source, see below. + * + * You can contact the author at: + * - xxHash homepage: http://cyan4973.github.io/xxHash/ + * - xxHash source repository: https://github.com/Cyan4973/xxHash + */ +#include "config.h" +#include "util.h" + +#define xxh_rotl32(x, r) ((x << r) | (x >> (32 - r))) + +static const sqfs_u32 PRIME32_1 = 2654435761U; +static const sqfs_u32 PRIME32_2 = 2246822519U; +static const sqfs_u32 PRIME32_3 = 3266489917U; +static const sqfs_u32 PRIME32_4 = 668265263U; +static const sqfs_u32 PRIME32_5 = 374761393U; + +static sqfs_u32 xxh32_round(sqfs_u32 seed, sqfs_u32 input) +{ + seed += input * PRIME32_2; + seed = xxh_rotl32(seed, 13); + seed *= PRIME32_1; + return seed; +} + +sqfs_u32 xxh32(const void *input, const size_t len) +{ + const sqfs_u8 *p = (const sqfs_u8 *)input; + const sqfs_u8 *b_end = p + len; + sqfs_u32 h32; + + if (len >= 16) { + const sqfs_u8 *const limit = b_end - 16; + sqfs_u32 v1 = PRIME32_1 + PRIME32_2; + sqfs_u32 v2 = PRIME32_2; + sqfs_u32 v3 = 0; + sqfs_u32 v4 = PRIME32_1; + + do { + v1 = xxh32_round(v1, ((sqfs_u32 *)p)[0]); + v2 = xxh32_round(v2, ((sqfs_u32 *)p)[1]); + v3 = xxh32_round(v3, ((sqfs_u32 *)p)[2]); + v4 = xxh32_round(v4, ((sqfs_u32 *)p)[3]); + p += 16; + } while (p <= limit); + + h32 = xxh_rotl32(v1, 1) + xxh_rotl32(v2, 7) + + xxh_rotl32(v3, 12) + xxh_rotl32(v4, 18); + } else { + h32 = PRIME32_5; + } + + h32 += (sqfs_u32)len; + + while (p + 4 <= b_end) { + h32 += (*((sqfs_u32 *)p)) * PRIME32_3; + h32 = xxh_rotl32(h32, 17) * PRIME32_4; + p += 4; + } + + while (p < b_end) { + h32 += (*p) * PRIME32_5; + h32 = xxh_rotl32(h32, 11) * PRIME32_1; + p++; + } + + h32 ^= h32 >> 15; + h32 *= PRIME32_2; + h32 ^= h32 >> 13; + h32 *= PRIME32_3; + h32 ^= h32 >> 16; + return h32; +} |