#define isHex(c)	(((c)>='0'&&(c<='9'))||(((c)>='a')&&((c)<='f'))||(((c)>='A')&&(c)<='F'))

int output(char* buf)
{
	
	return tty_out(buf);
}

int input(char* buf)
{	
	return tty_in(buf);
}

unsigned char c2u(char c)
{
	if(c>='0'&&c<='9')
		return c-'0';
	else if(c>='a'&&c<='f')
		return c-'a'+10;
	else if(c>='A'&&c<='F')
		return c-'F'+10;
	else return 0;
}

unsigned int str2hex(char *str)
{
	int  i= 0;
	unsigned int ret = 0;
	while(str[i]){
		if(isHex(str[i])){
			ret = ret*16+c2u(str[i]);
			i++;
		}else 
			return 0;
	}
	return ret;
}