shithub: femtolisp

ref: 7bcf6ac7b612306d197d063aaf6d971ca5dd2e3f
dir: /htable.c/

/*
  functions common to all hash table instantiations
*/

#include "flisp.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 = MEM_ALLOC(size*sizeof(void*));
	}
	if(h->table == nil)
		return nil;
	size_t i;
	for(i = 0; i < size; i++)
		h->table[i] = HT_NOTFOUND;
	h->i = 0;
	return h;
}

void
htable_free(htable_t *h)
{
	if(h->table != &h->_space[0])
		MEM_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 = MEM_REALLOC(h->table, newsz*sizeof(void*));
		if(newtab == nil)
			return;
		h->size = newsz;
		h->table = newtab;
	}
	size_t i, hsz = h->size;
	for(i = 0; i < hsz; i++)
		h->table[i] = HT_NOTFOUND;
}