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

#define aliases __attribute__((__may_alias__))
#define byte_repeat(x) ((size_t)~0 / 0xff * (x))
#define word_has_zero(x) (((x) - byte_repeat(0x01)) & ~(x) & byte_repeat(0x80))
#define weak_alias(o, n) extern __typeof__(o) n __attribute__((weak, alias(#o)))

char *__strchrnul(const char *_s, int i)
{
	i = (unsigned char)i;
	const unsigned char *s = (const void *)_s;
	const size_t aliases *ws, wi = byte_repeat(i);

	if (!i) return (char *)s + strlen((char *)s);

	for (; (uintptr_t)s & sizeof(size_t) - 1 && *s && *s != i; s++);
	if ((uintptr_t)s & sizeof(size_t) - 1) return (char *)s;

	ws = (const void *)s;
	for (; !word_has_zero(*ws) && !word_has_zero(*ws ^ wi); ws++);
	s = (const void *)ws;

	for (; *s && *s != i; s++);

	return (char *)s;
}

weak_alias(__strchrnul, strchrnul);