// Here's a little example to help explain the radix digit processing for asn 6
// I put it on the web page as "masking.c"
#include <stdio.h>
main() {
	int n, radix, digit, mask;
	// In base ten we would have to shift digits by dividing
	// and then extract a digit using the modulus operation.
	// For example to get the 4th radix 10 digit from a number n
	n = 123456789;
	radix = 10;
	digit = (n / (radix*radix*radix)) % radix;
	printf("n %d    the 4th base 10 digit is %d\n", n, digit);
	// To get the series of digits in order we can loop ...
	for( ; n; n /= radix)
		printf("digit is %d\n", n % radix);
	// The same logic works in other bases so for base 8 octal
	n = 01234567;
	radix = 8;
	printf("octal n is 0%o\n", n);
	for( ; n; n /= radix)
		printf("octal digit is %d\n", n % radix);
	// Or for base 16 hexadecimal
	n = 0x1234ABCD;
	radix = 16;
	printf("hex n is 0x%x\n", n);
	for( ; n; n /= radix)
		printf("hex digit is %d = 0x%x\n", n % radix, n % radix);
	// Or for base 2 binary
	n = 0x1234ABCD;
	printf("hex n is 0x%x\n", n);
	radix = 2;
	for( ; n; n /= radix)
		printf("binary digit is %d\n", n % radix);
	// However, division is very slow so we can do things much
	// more quickly by working with bases that are powers of 2
	// so we can do digit extraction by bit shifting and masking.
	// The previous example in base 2 is also ...
	n = 0x1234ABCD;
	printf("hex n is 0x%x\n", n);
	for( ; n; n >>= 1)
		printf("binary digit is %d\n", n & 1);
	// Redone in radix 16 to give hex digits by 4 bit shifts and 0xF mask
	n = 0x1234ABCD;
	printf("hex n is 0x%x\n", n);
	for( ; n; n >>= 4)	// shift by 4 bits and mask with 0xF which is 15
		printf("hex digit is %d = 0x%x\n", n & 0xF, n & 0xF);
	// Notice that for any power of 2 radix, like 16 above, the mask
	// is just radix-1 and the shift is the number of trailing 0's
	// in the binary representation.  That should let you understand
	// the defines that are in the asn6 template ...
#define BITS    8       /* specify the radix by number of bits it uses */
#define RADIX   (1<<BITS)
#define DIGITS  (32/BITS)
}