static char x2c(char *hex) {
        register char digit;
        digit = ((hex[0] >= 'A') ? ((hex[0] & 0xdf) - 'A')+10 : (hex[0] - '0'));
        digit *= 16;
        digit += (hex[1] >= 'A' ? ((hex[1] & 0xdf) - 'A')+10 : (hex[1] - '0'));
        return(digit);
}
The software reads data past the end, or before the beginning, of the intended buffer.