#include <string.h>
#include "ucore/heapsort.h"

static void
uc_sift(unsigned char *base, size_t start, size_t count, size_t width,
     uc_hs_cmp cmp)
{
    size_t root = start, child;

    while ((root * 2 + 1) < count) {
        child = root * 2 + 1;
        if (child < (count - 1)
            && cmp(&base[child * width], &base[(child + 1) * width]) < 0)
            child++;

        if (cmp(&base[root * width], &base[child * width]) < 0) {
            memcpy(base + root * width, base + child * width, width);
            root = child;
        } else
            return;
    }
}

void
uc_heapsort(void *base_, size_t count, size_t width,
     uc_hs_cmp cmp)
{
    int start = count / 2 - 1, end = count - 1;
    unsigned char *base = base_;

    while (start >= 0) {
        uc_sift(base, start, count, width, cmp);
        start--;
    }

    while (end > 0) {
        memcpy(base + end * width, base, width);
        uc_sift(base, 0, end, width, cmp);
        end--;
    }
}