swap.c


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#include <stddef.h>
#include <stdint.h>

#include "common.h"
#include "counts.h"

void swap(char *a, char *b, size_t width)
{
	counts[CURRENT].swap++;

#ifdef __GNUC__
	typedef uint32_t __attribute__((__may_alias__)) u32;

	if ((uintptr_t)a % 4 == 0 && (uintptr_t)b % 4 == 0) {
		for (; width >= 4; width -= 4) {
			uint32_t tmp = *((u32*)a);
			*((u32*)a) = *((u32*)b);
			*((u32*)b) = tmp;
			a += 4;
			b += 4;
		}
	}
#endif

	while (width--) {
		char tmp = *a;
		*a++ = *b;
		*b++ = tmp;
	}
}