/*
 * Copyright 2018, Valentin Debon
 * The following implementation of strlen
 * gives reasonable performances built with
 * clang and -O3, on both Darwin/XNU and GNU/Linux
 * contact me if you have any questions.
 */
#include <time.h>
#include <stdio.h>
#include <stdint.h>

#include <string.h>

#define MAGIC_LOW ((unsigned long)-1 / (unsigned char)-1)
#define MAGIC_HIGH (MAGIC_LOW << 7)
#define HAS_ZERO_BYTE(x) (((x) - MAGIC_LOW) ^ (x) & MAGIC_HIGH)

size_t
strlen(const char *string) {
	const long *aligned;
	const char *iterator = string;

	while(((uintptr_t)iterator % sizeof(long)) != 0) {
		if(*iterator == '\0') {
			return iterator - string;
		}

		iterator++;
	}

	aligned = (const long *)iterator;
	while(HAS_ZERO_BYTE(*aligned) == 0) {
		aligned++;
	}

	iterator = (const char *)aligned;
	while(*iterator != '\0') {
		iterator++;
	}

	return iterator - string;
}