diff options
Diffstat (limited to 'stc/cmap.h')
| -rw-r--r-- | stc/cmap.h | 31 |
1 files changed, 31 insertions, 0 deletions
@@ -197,6 +197,10 @@ ctype##_##tag##_begin(ctype##_##tag* map); \ STC_API void \
ctype##_##tag##_next(ctype##_##tag##_iter_t* it); \
\
+STC_API uint32_t c_default_hash(const void *data, size_t len); \
+STC_API uint32_t c_fibonacci_hash32(const void* data, size_t len); \
+STC_API uint32_t c_fibonacci_hash64(const void* data, size_t len); \
+ \
implement_CHASH(tag, ctype, Key, Value, valueDestroy, keyEqualsRaw, keyHashRaw, \
keyDestroy, RawKey, keyToRaw, keyFromRaw) \
typedef Key ctype##_##tag##_key_t; \
@@ -375,6 +379,33 @@ ctype##_##tag##_next(ctype##_##tag##_iter_t* it) { \ while (++it->item != it->end && *++it->_hx == 0) ; \
}
+
+/* One-byte-at-a-time hash based on Murmur's mix */
+STC_API uint32_t c_default_hash(const void *data, size_t len) {
+ const volatile uint8_t *key = (const uint8_t *) data;
+ uint32_t x = UINT32_C(0xc613fc15);
+ while (len--) {
+ x ^= *key++;
+ x *= UINT32_C(0x5bd1e995);
+ x ^= x >> 15;
+ }
+ return x;
+}
+/* https://programmingpraxis.com/2018/06/19/fibonacci-hash */
+/* https://probablydance.com/2018/06/16/fibonacci-hashing-the-optimization-that-the-world-forgot-or-a-better-alternative-to-integer-modulo/ */
+STC_API uint32_t c_fibonacci_hash32(const void* data, size_t len) {
+ const volatile uint32_t *key = (const uint32_t *) data;
+ uint32_t x = *key++ * 2654435769u;
+ while (len -= 4) x ^= *key++ * 2654435769u;
+ return x;
+}
+STC_API uint32_t c_fibonacci_hash64(const void* data, size_t len) {
+ const volatile uint64_t *key = (const uint64_t *) data;
+ uint64_t x = *key++ * 11400714819323198485ull;
+ while (len -= 8) x ^= *key++ * 11400714819323198485ull;
+ return (uint32_t) x; // (x >> 13);
+}
+
#else
#define implement_CHASH(tag, ctype, Key, Value, valueDestroy, keyEqualsRaw, keyHashRaw, \
keyDestroy, RawKey, keyToRaw, keyFromRaw)
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