On Fri, 2010-04-30 at 12:07 -0700, Andrew Morton wrote:
> I had to fiddle with it:
> - use tolower(), saving 3 bytes!

tolower could be done after the 0-9 case as well

int hex_to_bin(char ch)
{
	if ((ch >= '0') && (ch <= '9'))
		return ch - '0';
	ch = tolower(ch);
	if ((ch >= 'a') && (ch <= 'f'))
		return ch - 'a' + 10;
	return -1;
}