#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, uc_hs_swp swap, void *cookie)
{
    size_t root = start, child;

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

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

void
uc_heapsort(void *base_, size_t count, size_t width,
     uc_hs_cmp cmp, uc_hs_swp swap, void *cookie)
{
    long start;
    long end;
    unsigned char *base = base_;

    if (count == 0 || width == 0) {
        return;
    }

    start = count / 2 - 1, 
    end = count - 1;

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

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