static int php_htoi(char *s)
{
	int value;
	int c;

	c = ((unsigned char *)s)[0];
	if (isupper(c))
		c = tolower(c);
	value = (c >= '0' && c <= '9' ? c - '0' : c - 'a' + 10) * 16;

	c = ((unsigned char *)s)[1];
	if (isupper(c))
		c = tolower(c);
	value += c >= '0' && c <= '9' ? c - '0' : c - 'a' + 10;

	return (value);
}
Unknown