hexval
code = (hexval(p[1]) << 12) | (hexval(p[2]) << 8) |
(hexval(p[3]) << 4) | hexval(p[4]);
*binnum++ = 16 * hexval(hexnum[2*i]) + hexval(hexnum[2*i+1]);
static char hexval( char );
return (16 * hexval(toupper(s[1])) + hexval(toupper(s[2])));
ch = hexval(*(ppos++));
ch2 = hexval(*(ppos++));
ch2 = hexval(ch);
ch3 = hexval(ch);
static int hexval(char c);