huff_code_t *
huff_code_build_str(char * const *values, int32 const *frequencies, int nvals)
{
huff_code_t *hc;
huff_node_t *root;
heap_t *q;
int i;
hc = (huff_code_t*)ckd_calloc(1, sizeof(*hc));
hc->refcount = 1;
hc->type = HUFF_CODE_STR;
/* Initialize the heap with nodes for each symbol. */
q = heap_new();
for (i = 0; i < nvals; ++i) {
heap_insert(q,
huff_node_new_str(values[i]),
frequencies[i]);
}
/* Now build the tree, which gives us codeword lengths. */
root = huff_code_build_tree(q);
heap_destroy(q);
if (root == 0 || root->nbits > 32) {
E_ERROR("Huffman trees currently limited to 32 bits\n");
huff_node_free_str(root, TRUE);
huff_code_free(hc);
return 0;
}
/* Build a canonical codebook. */
hc->maxbits = root->nbits;
huff_code_canonicalize(hc, root);
/* Tree no longer needed (note we retain pointers to its strings). */
huff_node_free_str(root, FALSE);
return hc;
}
huff_code_t *
huff_code_build_int(int32 const *values, int32 const *frequencies, int nvals)
{
huff_code_t *hc;
huff_node_t *root;
heap_t *q;
int i;
hc = ckd_calloc(1, sizeof(*hc));
hc->refcount = 1;
hc->type = HUFF_CODE_INT;
/* Initialize the heap with nodes for each symbol. */
q = heap_new();
for (i = 0; i < nvals; ++i) {
heap_insert(q,
huff_node_new_int(values[i]),
frequencies[i]);
}
/* Now build the tree, which gives us codeword lengths. */
root = huff_code_build_tree(q);
heap_destroy(q);
if (root == NULL || root->nbits > 64) {
E_ERROR("Huffman trees currently limited to 32 bits\n");
huff_node_free_int(root);
huff_code_free(hc);
return NULL;
}
/* Build a canonical codebook. */
hc->maxbits = root->nbits;
huff_code_canonicalize(hc, root);
/* Tree no longer needed. */
huff_node_free_int(root);
return hc;
}
