交换数组的两部分

reserve.c

#include <stddef.h>

#define TYPE_SWAP(a,b) do { TYPE t = (a); (a) = (b); (b) = t; } while (0)
static inline void _reverse(TYPE *base, size_t n)
{
	size_t i = 0;
	for (i = 0; i < n/2; i++)
		TYPE_SWAP(base[i], base[n - i - 1]);
}

void reverse(TYPE *base, size_t n, size_t i)
{
	_reverse(base, i);
	_reverse(base + i, n - i);
	_reverse(base, n);
}

static inline void swap_array(TYPE *a, TYPE *b, size_t n)
{
	size_t i = 0;
	for (i = 0; i < n; i++)
		TYPE_SWAP(a[i], b[i]);
}

void reverse2(TYPE *base, size_t n, size_t i)
{
	while (n && i && i < n) {
		size_t m = n - i > i ? i : n - i;
		swap_array(base, base + n - m, m);
		if (m < i)
			base += m, i -= m;
		n -= m;
	}
}