size_t strlen2(const char *str) {
    const char *char_ptr;
    const unsigned long int *longword_ptr;
    unsigned long int longword, magic_bits, himagic, lomagic;

    for (char_ptr = str; ((unsigned long int) char_ptr & (sizeof(longword) - 1)) != 0; ++char_ptr)
        if (*char_ptr == '\0')
            return char_ptr - str;

    longword_ptr = (unsigned long int *) char_ptr;
    magic_bits = 0x7efefeffL;
    himagic = 0x80808080L;
    lomagic = 0x01010101L;
    if (sizeof(longword) > 4) {
        magic_bits = ((0x7efefefeL << 16) << 16) | 0xfefefeffL;
        himagic = ((himagic << 16) << 16) | himagic;
        lomagic = ((lomagic << 16) << 16) | lomagic;
    }
    if (sizeof(longword) > 8)
        abort();

    while (1) {
        longword = *longword_ptr++;
        if (((longword - lomagic) & himagic) != 0) {
            const char *cp = (const char *)(longword_ptr - 1);

            if (cp[0] == 0)
                return cp - str;
            if (cp[1] == 0)
                return cp - str + 1;
            if (cp[2] == 0)
                return cp - str + 2;
            if (cp[3] == 0)
                return cp - str + 3;
            if (sizeof (longword) > 4) {
                if (cp[4] == 0)
                    return cp - str + 4;
                if (cp[5] == 0)
                    return cp - str + 5;
                if (cp[6] == 0)
                    return cp - str + 6;
                if (cp[7] == 0)
                    return cp - str + 7;
            }
        }
    }
}