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Code Issues 1 Releases Wiki Activity

Add an extra has mix round to string hashes.

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This should improve hashing quality of strings.
This commit is contained in:
Calvin Rose 2024-11-17 11:31:12 -06:00
parent bafa6bfff0
commit 5d1bd8a932
1 changed files with 7 additions and 6 deletions
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13
src/core/util.c
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@ -117,14 +117,20 @@ const char *const janet_status_names[16] = {
"alive" "alive"
}; };
uint32_t janet_hash_mix(uint32_t input, uint32_t more) {
uint32_t mix1 = (more + 0x9e3779b9 + (input << 6) + (input >> 2));
return input ^ (0x9e3779b9 + (mix1 << 6) + (mix1 >> 2));
}
#ifndef JANET_PRF #ifndef JANET_PRF
int32_t janet_string_calchash(const uint8_t *str, int32_t len) { int32_t janet_string_calchash(const uint8_t *str, int32_t len) {
if (NULL == str) return 5381; if (NULL == str || len == 0) return 5381;
const uint8_t *end = str + len; const uint8_t *end = str + len;
uint32_t hash = 5381; uint32_t hash = 5381;
while (str < end) while (str < end)
hash = (hash << 5) + hash + *str++; hash = (hash << 5) + hash + *str++;
hash = janet_hash_mix(hash, (uint32_t) len);
return (int32_t) hash; return (int32_t) hash;
} }
@ -240,11 +246,6 @@ int32_t janet_string_calchash(const uint8_t *str, int32_t len) {
#endif #endif
uint32_t janet_hash_mix(uint32_t input, uint32_t more) {
uint32_t mix1 = (more + 0x9e3779b9 + (input << 6) + (input >> 2));
return input ^ (0x9e3779b9 + (mix1 << 6) + (mix1 >> 2));
}
/* Computes hash of an array of values */ /* Computes hash of an array of values */
int32_t janet_array_calchash(const Janet *array, int32_t len) { int32_t janet_array_calchash(const Janet *array, int32_t len) {
const Janet *end = array + len; const Janet *end = array + len;