shithub: femtolisp

ref: 0619fc6c8de5628a3682b0888c53e11a09889f54
dir: /llt/htable.c/

/*
  functions common to all hash table instantiations
*/

#ifdef PLAN9
#include <u.h>
#include <libc.h>
#else
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <limits.h>
#endif

#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;
}