54 lines
1.4 KiB
C
54 lines
1.4 KiB
C
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#include <lladd/hash.h>
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#include <math.h>
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/*static int thomasWangs32BitMixFunction(int key);
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static unsigned long thomasWangs64BitMixFunction(unsigned long key);*/
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/** @todo replace powl in hash with something more efficient, if hash() becomes a bottleneck. */
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unsigned int hash(void * val, long val_length, unsigned char tableBits, unsigned long nextExtension) {
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unsigned long tableLength = powl(2, tableBits);
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unsigned long oldTableLength = powl(2, tableBits - 1);
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unsigned long unmixed = crc32(val, val_length, (unsigned long)-1L);
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unsigned long ret = unmixed & (oldTableLength - 1);
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if(*(int*)val == 4090) {
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printf("here too!");
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}
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/* What would the low hash value be? */
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/* printf("hash(%d, bits=%d, ext=%ld) first: %ld ", *(int*)val, tableBits, nextExtension, ret); */
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if(ret < nextExtension) { /* Might be too low. */
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ret = unmixed & (tableLength - 1);
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/* printf("second: %ld", ret); */
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}
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/* printf("\n"); */
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return (int) ret;
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}
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/*static unsigned long thomasWangs64BitMixFunction(unsigned long key)
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{
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key += ~(key << 32L);
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key ^= (key >> 22L);
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key += ~(key << 13L);
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key ^= (key >> 8L);
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key += (key << 3L);
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key ^= (key >> 15L);
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key += ~(key << 27L);
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key ^= (key >> 31L);
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return key;
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}
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static int thomasWangs32BitMixFunction(int key)
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{
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key += ~(key << 15);
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key ^= (key >> 10);
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key += (key << 3);
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key ^= (key >> 6);
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key += ~(key << 11);
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key ^= (key >> 16);
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return key;
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}
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*/
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