88  * need for the L_CODES extra codes used during heap construction. However
479 /* Index within the heap array of least frequent node in the Huffman tree */
483  * Remove the smallest element from the heap and recreate the heap with
484  * one less element. Updates heap and heap_len.
488     top = s->heap[SMALLEST]; \
489     s->heap[SMALLEST] = s->heap[s->heap_len--]; \
502  * Restore the heap property by moving down the tree starting at node k,
504  * when the heap property is re-established (each father smaller than its
508     int v = s->heap[k];  in pqdownheap()
513             smaller(tree, s->heap[j + 1], s->heap[j], s->depth)) {  in pqdownheap()
517         if (smaller(tree, v, s->heap[j], s->depth)) break;  in pqdownheap()
520         s->heap[k] = s->heap[j];  k = j;  in pqdownheap()
525     s->heap[k] = v;  in pqdownheap()
531  * IN assertion: the fields freq and dad are set, heap[heap_max] and
545     int h;              /* heap index */  in gen_bitlen()
557     tree[s->heap[s->heap_max]].Len = 0; /* root of the heap */  in gen_bitlen()
560         n = s->heap[h];  in gen_bitlen()
601             m = s->heap[--h];  in gen_bitlen()
629     int n, m;          /* iterate over heap elements */  in build_tree()
633     /* Construct the initial heap, with least frequent element in  in build_tree()
634      * heap[SMALLEST]. The sons of heap[n] are heap[2*n] and heap[2*n + 1].  in build_tree()
635      * heap[0] is not used.  in build_tree()
641             s->heap[++(s->heap_len)] = max_code = n;  in build_tree()
654         node = s->heap[++(s->heap_len)] = (max_code < 2 ? ++max_code : 0);  in build_tree()
662     /* The elements heap[heap_len/2 + 1 .. heap_len] are leaves of the tree,  in build_tree()
673         m = s->heap[SMALLEST]; /* m = node of next least frequency */  in build_tree()
675         s->heap[--(s->heap_max)] = n; /* keep the nodes sorted by frequency */  in build_tree()
676         s->heap[--(s->heap_max)] = m;  in build_tree()
689         /* and insert the new node in the heap */  in build_tree()
690         s->heap[SMALLEST] = node++;  in build_tree()
695     s->heap[--(s->heap_max)] = s->heap[SMALLEST];  in build_tree()