source: buchla-68k/orig/GP/PRBITS.C

/*
   =============================================================================
        prbits.c -- print groups of bits from a number
        Version 1 -- 1988-09-21 -- D.N. Lynx Crowe
   =============================================================================
*/

#include "stdio.h"
#include "stddefs.h"

/*
   =============================================================================
        prbits(n, l, r, gs) -- print selected groups of bits of 'n'

                'n'     number to print bits from
                'r'     rightmost bit to use            starting with the LSB
                'l'     leftmost bit to use             starting with the LSB
                'gs'    bits in each group              starting on the right
   =============================================================================
*/

prbits(n, l, r, gs)
register long n;
register int l, r, gs;
{
        register char *bp;
        register int i;
        char buf[66];

        if (( l < 0) OR ( l > 31) OR
            ( r < 0) OR ( r > 31) OR
            (gs < 1) OR (gs > 32) OR
            ( r > l))
                return;

        bp    = &buf[65];
        *bp-- = '\0';

        for (i = r; i < (l + 1); i++) {

                if ((i NE 0) AND (0 EQ (i % gs)))
                        *bp-- = ' ';

                if (n & (1L << i))
                        *bp-- = '1';
                else
                        *bp-- = '0';
        }

        ++bp;

        if (*bp EQ ' ')
                ++bp;

        while ('\0' NE (c = *bp++))
                putchar(c);
}