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- /*
- * Copyright [2021] JD.com, Inc.
- *
- * 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 "da_hashkit.h"
- #define mix(a,b,c) \
- { \
- a=a-b; a=a-c; a=a^(c>>13); \
- b=b-c; b=b-a; b=b^(a<<8); \
- c=c-a; c=c-b; c=c^(b>>13); \
- a=a-b; a=a-c; a=a^(c>>12); \
- b=b-c; b=b-a; b=b^(a<<16); \
- c=c-a; c=c-b; c=c^(b>>5); \
- a=a-b; a=a-c; a=a^(c>>3); \
- b=b-c; b=b-a; b=b^(a<<10); \
- c=c-a; c=c-b; c=c^(b>>15); \
- }
- typedef uint32_t u4;
- uint32_t hash_chash(const char *k, size_t length)
- {
- uint32_t a,b,c; /* the internal state */
- u4 len; /* how many key bytes still need mixing */
- /* Set up the internal state */
- len = length;
- a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
- // 'TMJR'
- c = 0x544D4A52; /* variable initialization of internal state */
- /*---------------------------------------- handle most of the key */
- while (len >= 12)
- {
- a=a+(k[0]+((u4)k[1]<<8)+((u4)k[2]<<16) +((u4)k[3]<<24));
- b=b+(k[4]+((u4)k[5]<<8)+((u4)k[6]<<16) +((u4)k[7]<<24));
- c=c+(k[8]+((u4)k[9]<<8)+((u4)k[10]<<16)+((u4)k[11]<<24));
- mix(a,b,c);
- k = k+12; len = len-12;
- }
- /*------------------------------------- handle the last 11 bytes */
- c = c+length;
- switch(len) /* all the case statements fall through */
- {
- case 11: c=c+((u4)k[10]<<24);
- case 10: c=c+((u4)k[9]<<16);
- case 9 : c=c+((u4)k[8]<<8);
- /* the first byte of c is reserved for the length */
- case 8 : b=b+((u4)k[7]<<24);
- case 7 : b=b+((u4)k[6]<<16);
- case 6 : b=b+((u4)k[5]<<8);
- case 5 : b=b+k[4];
- case 4 : a=a+((u4)k[3]<<24);
- case 3 : a=a+((u4)k[2]<<16);
- case 2 : a=a+((u4)k[1]<<8);
- case 1 : a=a+k[0];
- /* case 0: nothing left to add */
- }
- mix(a,b,c);
- /*-------------------------------------------- report the result */
- return c;
- }
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