#include <stddef.h>
#include <stdlib.h>
#include <string.h>

int heapsort(void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *)) {
	ptrdiff_t i=1, j;
	void *tmp=malloc(size);
	base-=size;
	while(!(++i>nmemb)) {
		memcpy(tmp, base+(j=i)*size, size);
		while(j>1 && 0<compar(tmp, memcpy(base+j*size, base+(j>>1)*size, size)))
			j>>=1;
		memcpy(base+j*size, tmp, size);
	}
	while(--i>1) {
		memcpy(tmp, base+i*size, size);
		memcpy(base+i*size, base+(j=1)*size, size);
		do
			if(((j<<=1)+1)<i)
				j+=0>compar(base+j*size, base+(j+1)*size);
		while(j<i && 0>compar(tmp, memcpy(base+(j>>1)*size, base+j*size, size)));
		memcpy(base+(j>>1)*size, tmp, size);
	}
	free(tmp);
	return(0);
}