#include <string.h>
#include <stdint.h>

#define HIGHS(x) ((x) - ((x)*0-1) / 255 * 128)
#define LOWS(x) (((x)*0-1) / 255)
#define has_char(x, c) ((x) - LOWS(x) & ~(x) & HIGHS(x) ^ LOWS(x) * (c))

void *memccpy(void *restrict d, const void *restrict s, int c, size_t n)
{
	unsigned char *cd = (unsigned char *)d;
	const unsigned char *cs = (const unsigned char *)s;
	size_t *wd;
	const size_t *ws;

	c = (unsigned char)c;

	if ((uintptr_t)s % sizeof(size_t) != (uintptr_t)d % sizeof(size_t)
	    || n < sizeof(size_t))
		goto bytewise;

	for (; (uintptr_t)s % sizeof(size_t); *cd = *cs, cd++, cs++)
		if (*cs == c) return cd + 1;

	for (wd = (size_t *)d, ws = (const size_t *)s
	     ; !has_char(*ws, c) && n >= sizeof(size_t)
	     ; ws++, wd++, *wd = *ws);

	cd = (unsigned char *)wd;
	cs = (const unsigned char *)ws;

bytewise:
	for (; *cs != c; *cd = *cs, cs++, cd++, n--)
		if (!n) return NULL;

	return cd + 1;
}