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ugui/text_rendering/generic_hash.h

157 lines
8.1 KiB

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