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137 lines
6.5 KiB
137 lines
6.5 KiB
#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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#include <stdint.h>
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// FIXME: change the api to just one HASH_DECL to HASH_PROTO and HASH_DEFINE
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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 ((uint64_t)2654435769u)
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#define HASH_RATIO64 ((uint64_t)11400714819322457583u)
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// salt for string hashing
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#define HASH_SALT ((uint64_t)0xbabb0cac)
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/* Ready-made compares */
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static inline int hash_cmp_u32(uint32_t a, uint32_t b) { return a == b; }
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static inline int hash_cmp_u64(uint64_t a, uint64_t b) { return a == b; }
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static inline int hash_cmp_str(const char *a, const char *b) { return strcmp(a, b) == 0; }
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/* Ready-made hashes */
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static inline uint32_t hash_u64(uint64_t c)
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{
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return (uint64_t)((((uint64_t)c+HASH_SALT)*HASH_RATIO64)>>32);
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}
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static inline uint32_t hash_u32(uint32_t c)
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{
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return (uint32_t)((((uint64_t)c<<31)*HASH_RATIO64)>>32);
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}
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static inline uint32_t hash_str(const char *s)
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{
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uint32_t h = HASH_SALT;
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const uint8_t *v = (const uint8_t *)(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(htname, codetype, datatype, hashfn, cmpfn) \
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struct htname##_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 htname##_ref { \
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uint32_t items, size, exp; \
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struct htname##_entry bucket[]; \
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}; \
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\
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\
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struct htname##_ref * htname##_create(uint32_t size) \
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{ \
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if (!size || size > HASH_MAXSIZE) \
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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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uint32_t exp = 32-__builtin_clz(size-1); \
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size = 1<<(exp); \
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/* FIXME: check for intger overflow here */ \
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struct htname##_ref *ht = malloc(sizeof(struct htname##_ref)+sizeof(struct htname##_entry)*size); \
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if (ht) { \
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ht->items = 0; \
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ht->size = size; \
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ht->exp = exp; \
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memset(ht->bucket, 0, sizeof(struct htname##_entry)*size); \
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} \
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return ht; \
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} \
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\
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\
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void htname##_destroy(struct htname##_ref *ht) \
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{ \
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if (ht) free(ht); \
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} \
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\
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\
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static uint32_t htname##_lookup(struct htname##_ref *ht, uint32_t hash, uint32_t idx) \
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{ \
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if (!ht) return 0; \
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uint32_t mask = ht->size-1; \
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uint32_t step = (hash >> (32 - ht->exp)) | 1; \
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return (idx + step) & mask; \
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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 htname##_entry * htname##_search(struct htname##_ref *ht, codetype code)\
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{ \
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if (!ht) return NULL; \
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uint32_t h = hashfn(code); \
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for (uint32_t i=h, x=0; ; x++) { \
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i = htname##_lookup(ht, h, i); \
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if (x > (ht->size<<1) || \
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!ht->bucket[i].code || \
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cmpfn(ht->bucket[i].code, code) \
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) { \
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return &(ht->bucket[i]); \
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} \
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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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/* FIXME: this simply overrides the found item */ \
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struct htname##_entry * htname##_insert(struct htname##_ref *ht, struct htname##_entry *entry) \
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{ \
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struct htname##_entry *r = htname##_search(ht, entry->code); \
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if (r) { \
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if (!r->code) \
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ht->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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struct htname##_entry * htname##_remove(struct htname##_ref *ht, codetype code)\
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{ \
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if (!ht) return NULL; \
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struct htname##_entry *r = htname##_search(ht, code); \
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if (r) r->code = 0; \
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return r; \
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} \
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#endif
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