// SPDX-License-Identifier: GPL-2.0
//
//  Original LINUX kernel heap sort function
//  The original did not have any license marking
//  but it is assumed it the license is GPL
//
#include    <stdlib.h>

static void long_swap(void *a, void *b, int size)
{
	long t = *(long *)a;
	*(long *)a = *(long *)b;
	*(long *)b = t;
}

static void generic_swap(void *a, void *b, int size)
{
	char t;

	do {
		t = *(char *)a;
		*(char *)a++ = *(char *)b;
		*(char *)b++ = t;
	} while (--size > 0);
}

void sortlinux(void *base, size_t num, size_t size,
	  int (*cmp_func)(const void *, const void *),
	  void (*swap_func)(void *, void *, int size))
{
	/* pre-scale counters for performance */
	int i = (num/2 - 1) * size, n = num * size, c, r;

	if (!swap_func)
		swap_func = (size == sizeof(long) ? long_swap : generic_swap);

	/* heapify */
	for ( ; i >= 0; i -= size) {
		for (r = i; r * 2 + size < n; r = c) {
			c = r * 2 + size;
			if (c < n - size &&
					cmp_func(base + c, base + c + size) < 0)
				c += size;
			if (cmp_func(base + r, base + c) >= 0)
				break;
			swap_func(base + r, base + c, size);
		}
	}

	/* sort */
	for (i = n - size; i > 0; i -= size) {
		swap_func(base, base + i, size);
		for (r = 0; r * 2 + size < i; r = c) {
			c = r * 2 + size;
			if (c < i - size &&
					cmp_func(base + c, base + c + size) < 0)
				c += size;
			if (cmp_func(base + r, base + c) >= 0)
				break;
			swap_func(base + r, base + c, size);
		}
	}
}