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157 lines
8.1 KiB
157 lines
8.1 KiB
2 years ago
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#ifndef _HASH_GENERIC
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#define _HASH_GENERIC
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#include <string.h>
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#include <stdlib.h>
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#define HASH_MAXSIZE 4096
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// for fibonacci hashing, 2^{32,64}/<golden ratio>
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#define HASH_RATIO32 (unsigned int)2654435769u
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#define HASH_RATIO64 (unsigned long long int)11400714819322457583u
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// salt for string hashing
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#define HASH_STRSALT 0xbabb0cac
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/* Ready-made compares */
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int hash_compare_u32(unsigned int a, unsigned int b) { return a == b; }
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int hash_compare_u64(unsigned long long int a, unsigned long long int b) { return a == b; }
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int hash_compare_str(const char *a, const char *b) { return strcmp(a, b) == 0; }
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/* Ready-made hashes */
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unsigned int hash_u64(unsigned long long int c)
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{
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return (unsigned long long int)((unsigned long long int)(c*HASH_RATIO64)>>32);
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}
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unsigned int hash_u32(unsigned int c)
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{
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return (unsigned int)((unsigned long long int)(c*HASH_RATIO32)>>32);
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}
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unsigned int hash_str(const char *s)
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{
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unsigned int h = HASH_STRSALT;
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const unsigned char *v = (const unsigned char *)(s);
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for (int x = *s; x; x--) {
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h += v[x-1];
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h += h << 10;
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h ^= h >> 6;
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}
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h += h << 3;
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h ^= h >> 11;
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h += h << 15;
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return h;
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}
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#define HASH_DECL(hashname, codetype, datatype) \
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struct hashname##_entry { \
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codetype code; \
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datatype data; \
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}; \
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\
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struct hashname##_ref { \
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unsigned int items, size; \
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/* Function pointer to hash function */ \
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unsigned int (*hash)(codetype); \
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/* Compare codetype function, return true if equal */ \
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int (*compare)(codetype, codetype); \
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struct hashname##_entry bucket[]; \
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}; \
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\
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\
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struct hashname##_ref * hashname##_create(unsigned int size, unsigned int (*hash)(codetype), int (*compare)(codetype, codetype)) \
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{ \
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if (!size || size > HASH_MAXSIZE) \
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return NULL; \
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if (!hash || !compare) \
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return NULL; \
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/* round to the greater power of two */ \
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/* FIXME: check for intger overflow here */ \
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size = 1<<__builtin_clz(size); \
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/* FIXME: check for intger overflow here */ \
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struct hashname##_ref *h = malloc(sizeof(struct hashname##_ref)+sizeof(struct hashname##_entry)*size); \
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if (h) { \
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h->items = 0; \
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h->size = size; \
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h->hash = hash; \
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h->compare = compare; \
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memset(h->bucket, 0, sizeof(struct hashname##_ref)*size); \
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} \
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return h; \
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} \
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\
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\
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void hashname##_destroy(struct hashname##_ref *hm) \
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{ \
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if (hm) \
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free(hm); \
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} \
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\
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\
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static struct hashname##_entry * hashname##lookup(struct hashname##_ref *hm, codetype code) \
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{ \
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if (!hm) \
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return NULL; \
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/* fast modulo operation for power-of-2 size */ \
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unsigned int mask = hm->size - 1; \
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unsigned int i = hm->hash(code); \
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for (unsigned int j = 1; ; i += j++) { \
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if (!hm->bucket[i&mask].code || hm->compare(hm->bucket[i].code, code)) \
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return &(hm->bucket[i&mask]); \
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} \
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return NULL; \
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} \
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\
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\
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/* Find and return the element by code */ \
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struct hashname##_entry * hashname##_search(struct hashname##_ref *hm, codetype code) \
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{ \
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if (!hm) \
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return NULL; \
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struct hashname##_entry *r = hashname##lookup(hm, code); \
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if (r && hm->compare(r->code, code)) \
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return r; \
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return NULL; \
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} \
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\
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\
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/* FIXME: this simply overrides the found item */ \
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struct hashname##_entry * hashname##_insert(struct hashname##_ref *hm, struct hashname##_entry *entry) \
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{ \
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struct hashname##_entry *r = hashname##lookup(hm, entry->code); \
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if (r) { \
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if (!r->code) \
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hm->items++; \
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*r = *entry; \
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} \
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return r; \
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} \
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\
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\
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/* returns the number of removed items */ \
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int hashname##_remove(struct hashname##_ref *hm, codetype code) \
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{ \
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if (!hm) \
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return -1; \
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unsigned int mask = hm->size - 1; \
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unsigned int s = hm->hash(code)&mask, inc = 0; \
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struct hashname##_entry *r; \
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/* Flag for removal */ \
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while (hm->items > 0 && (r = hashname##lookup(hm, code)) && r->code) { \
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/* FIXME: this cast may not work */ \
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r->code = (codetype)(-1); \
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hm->items--; \
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} \
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/* Remove */ \
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for (unsigned int i = s; i < hm->items; i++) { \
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if (hm->bucket[i].code == (codetype)(-1)) { \
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hm->bucket[i] = (struct hashname##_entry){0}; \
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inc++; \
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} \
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} \
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return inc; \
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} \
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#endif
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