femtolisp/llt/htable.c

57 lines
1.3 KiB
C

/*
functions common to all hash table instantiations
*/
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <limits.h>
#include "dtypes.h"
#include "htable.h"
#include "hashing.h"
htable_t *htable_new(htable_t *h, size_t size)
{
if (size <= HT_N_INLINE/2) {
h->size = size = HT_N_INLINE;
h->table = &h->_space[0];
}
else {
size = nextipow2(size);
size *= 2; // 2 pointers per key/value pair
size *= 2; // aim for 50% occupancy
h->size = size;
h->table = (void**)LLT_ALLOC(size*sizeof(void*));
}
if (h->table == NULL) return NULL;
size_t i;
for(i=0; i < size; i++)
h->table[i] = HT_NOTFOUND;
return h;
}
void htable_free(htable_t *h)
{
if (h->table != &h->_space[0])
LLT_FREE(h->table);
}
// empty and reduce size
void htable_reset(htable_t *h, size_t sz)
{
sz = nextipow2(sz);
if (h->size > sz*4 && h->size > HT_N_INLINE) {
size_t newsz = sz*4;
void **newtab = (void**)LLT_REALLOC(h->table, newsz*sizeof(void*));
if (newtab == NULL)
return;
h->size = newsz;
h->table = newtab;
}
size_t i, hsz=h->size;
for(i=0; i < hsz; i++)
h->table[i] = HT_NOTFOUND;
}