| /* |
| * |
| * Copyright 2015 gRPC authors. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| * |
| */ |
| |
| #include "src/core/lib/support/murmur_hash.h" |
| |
| #include <string.h> |
| |
| #define ROTL32(x, r) ((x) << (r)) | ((x) >> (32 - (r))) |
| |
| #define FMIX32(h) \ |
| (h) ^= (h) >> 16; \ |
| (h) *= 0x85ebca6b; \ |
| (h) ^= (h) >> 13; \ |
| (h) *= 0xc2b2ae35; \ |
| (h) ^= (h) >> 16; |
| |
| uint32_t gpr_murmur_hash3(const void *key, size_t len, uint32_t seed) { |
| const uint8_t *data = (const uint8_t *)key; |
| const size_t nblocks = len / 4; |
| int i; |
| |
| uint32_t h1 = seed; |
| uint32_t k1; |
| |
| const uint32_t c1 = 0xcc9e2d51; |
| const uint32_t c2 = 0x1b873593; |
| |
| const uint32_t *blocks = ((const uint32_t *)key) + nblocks; |
| const uint8_t *tail = (const uint8_t *)(data + nblocks * 4); |
| |
| /* body */ |
| for (i = -(int)nblocks; i; i++) { |
| memcpy(&k1, blocks + i, sizeof(uint32_t)); |
| |
| k1 *= c1; |
| k1 = ROTL32(k1, 15); |
| k1 *= c2; |
| |
| h1 ^= k1; |
| h1 = ROTL32(h1, 13); |
| h1 = h1 * 5 + 0xe6546b64; |
| } |
| |
| k1 = 0; |
| |
| /* tail */ |
| switch (len & 3) { |
| case 3: |
| k1 ^= ((uint32_t)tail[2]) << 16; |
| /* fallthrough */ |
| case 2: |
| k1 ^= ((uint32_t)tail[1]) << 8; |
| /* fallthrough */ |
| case 1: |
| k1 ^= tail[0]; |
| k1 *= c1; |
| k1 = ROTL32(k1, 15); |
| k1 *= c2; |
| h1 ^= k1; |
| }; |
| |
| /* finalization */ |
| h1 ^= (uint32_t)len; |
| FMIX32(h1); |
| return h1; |
| } |