script to convert numbers/expressions to hex/oct/dec/binary

bits

#! /usr/bin/perl

sub Usage {
  $0 =~ s#.*/##g;
  die <<EOM;
Usage: $0 [-hodsbn] expr [...]

    expr may contain decimal/hex/octal numbers and operators, unless expr
    is suffixed with b, in which case it is interpreted as a binary number
    and operators are not allowed.

    Converts to hex, octal, signed decimal, unsigned decimal, and binary,
    and also indicates which bits are set. Flags may be used to turn off
    specific conversions:
        h = hex, o = oct, d = dec, s = signed dec, b = binary, n = set bits

EOM
}

use Getopt::Std;

Usage() unless (getopts("hodsbn"));
Usage() if ($#ARGV == -1);

foreach $arg (@ARGV) {
  if ($arg =~ /^[01]*b$/) {
    # convert from binary.
    $num = 0;
    $idx = 0;
    chop $arg;
    while ($arg ne "")
    {
      $bit = chop $arg;
      last if (($bit ne "0") && ($bit ne "1"));
      $num |= (1 << $idx) if ($bit eq "1");
      ++$idx;
    }
  } else {
    # TODO this can produce perl error messages on the tty; it might be
    # nice to be a little cleaner about it.
    $num = eval "$arg";
  }

  printf "0x%08x ", $num  unless $opt_h;
  printf "%012o ", $num   unless $opt_o;
  printf "%10u ", $num    unless $opt_d;
  printf "%11d ", $num    unless $opt_s;

  # convert to binary
  undef $bits;
  for ($i = 31; $i >= 0; --$i) {
    if ($num & (1 << $i)) {
      $bits .= " $i";
      print "1" unless $opt_b;
    } else {
      print "0" unless $opt_b;
    }
  }

  print "\n";
  print "set:$bits\n\n" unless $opt_n;
}

TODO: I wrote this a long time ago and it assumes 32 bits, which affects 2 things (see the example for -100 above):

• binary conversion (and bits set:) only looks at the lowest 32 bits
• the other conversions do use 64 bits on a 64 bit machine, but it throws off the column widths which were chosen to be wide enough for 32 bit numbers.