#!/usr/local/bin/perl

# NOTES:
$USAGE = '
SYNOPSIS: Nifty Programmable Scientific Calculator
AUTHOR: GPL(C) Mohsin Ahmed, http://www.cs.albany.edu/~mosh
USAGE:
 c:/> pc                                 ... interactive mode.
      1222/3; sin($pi/4); $x = $pi/$e; $x**100; p;
      exit;
 c:/> pc  "231+2**20" "0xffff-99"        ... batch mode
NOTES:
 - Math Functions: +,-,/,*,**,sqrt,log,sin,cos,tan,atan2;
   &,|,^,complex i;
 - Ouput: tobin, tohex, tooct,
   p (prints argument or last answer in all formats).
 - Perl Control (while,for,if,else);
   Variables (string,int,floats,arrays);
 Use $ans[N] or $ans to refer to previous or last answers.
 Use the arrow keys for editing history, which due to some quirk
     remains intact between sessions (95/NT).
'
 ;

$verbose=0;

# TODO: Extend to bigints and bigfloats, but no libs on mswin!
# # Libs not on windows.
# use Math::BigFloat;
# use Math::Complex;
# CONSTANTS
# $pi=new Math::BigFloat atan2(1,1)*4;
# $e=exp(1);

$pi  = 3.14159264;
$deg = $pi/180;

%const = (
    'pi'    => $pi,
    'deg'   => $pi/180,
);


# If command line args are given, process it and exit.

if( @ARGV ){
    foreach $expr (@ARGV) {
        print "$expr = ",&p( eval $expr ),"\n";
    }
    exit;
}

# Else go into interactive mode until EOF or exit.



print STDERR $USAGE, 'Input:';

while(<>){
    chop;
    $ans[++$line] = $ans = eval $_;
    print STDERR "\$ans[$line] = eval $_ = $ans;\n Input:";
}

# Convert binary to decimal, 32 bits, etc. -1 = ffff_ffff.
# NTperl5, some limits are 16 bit.
# hex(ff) = 255, tohex( 255 ) = 0xff (use for input).
# oct(77) = 63,  tooct( 63 ) = 077 (use for input).

sub tohex { sprintf( "0x%lx", @_ ); }
sub tooct { sprintf( "0%lo", @_ ); }

# Print arg [last ans] in many formats.

sub p {                                              # print function.
    @_ = int($ans) unless @_;  # Use last answer as default?
    my($c) = @_;
    sprintf( "\n"
         .  "\t= sci   %lg \n"
         .  "\t= dec   %ld \n"
         .  "\t= char '%c'%c'%c'%c'\n"
         .  "\t= ip   '%d.%d.%d.%d'\n"
         .  "\t= hex   0x%lx   \n"
         .  "\t= octal 0%lo    \n"
         .  "\t= bin   %s"
         , $c, $c,
            $c, $c>>8, $c>>16, $c>>24,
            $c & 0xff, $c>>8 & 0xff, $c>>16 & 0xff, $c>>24 & 0xff,
            $c,
            $c,
            tobin($c) );
}
# Convert an integer to a string of 0 and 1.

sub tobin {
    my( $in ) = @_;
    my( $bin, $rem, ) = "";
    $in = int($in);
    while( $in > 0 ){
        if( $rem = ($in & 1) ){
            $bin .= '1';
        }else{
            $bin .= '0';
        }
        $in = int($in>>1);
    }
    $bin =~ s/(....)/$1_/g;
    join( "", reverse( split(//,$bin) ));
}

# Works for arbitary size, but only 32 digit accuracy.
# input can be a huge float number.

sub floattobin {
    my( $in ) = @_;
    my( $bin ) = "";
    while( int($in) > 0 ){
        print "*(* bin=$bin, in=$in\n" if $verbose;
        $bin .=  ($in % 2);
        $in /= 2;
        print "*)* bin=$bin, in=$in\n" if $verbose;
    }
    $bin =~ s/(....)/$1_/g;
    join( "", reverse( split(//,$bin) ));
}

sub bintodec {
    unpack("N", pack("B32", substr("0" x 32 . shift, -32)));
}

# EOF