#!/usr/bin/perl
# 
# Copyright © 2015-2020 by Vincent Slyngstad
# 
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
# 
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
# 
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS LISTED ABOVE BE LIABLE
# FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
# CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
# 
# Except as contained in this notice, the names of the authors above
# shall not be used in advertising or otherwise to promote the sale, use
# or other dealings in this Software without prior written authorization
# from those authors.

#
# Convert a .bin file to readable stream.
#
#2345678901234567890123456789012345678901234567890123456789012345678901234567890

open(INPUT, "$ARGV[0]") || die "$ARGV[0] open: $!";
binmode(INPUT);

#
# Get a character as an integer byte value.
sub getch {
    local($c);

    return unpack("C", $c) if read(INPUT,$c,1);
#warn "$ARGV[0] read: $!";
    return undef;
}

#
# Ignore leader in the .bin file.
while (($c1 = getch(INPUT)) == 0200) { }
$checksum = 0;
$loc = undef;
$data = undef;
while (1) {
#warn "c1 $c1\n";
    # Is it the start of a comment?
    if ($c1 == 0377) {
        # Yes, look for the other end.
        print "<del>";
        while (($c1 = getch(INPUT)) != 0377) {
            print pack("C", $c1);
	}
        print "<del>\n";
        $c1 = getch(INPUT);
        next;
    }
    # Is it a field setting or trailer?
    if ($c1&0200) {
	# Neither a field settings or trailer should change $checksum.
        # Is it a field setting?
        if ($c1&0100) {
	    if (defined $data) {
		printf "%04o ", $data;
		$loc++;
	    }
            undef $data;
	    printf "\nFIELD %o\n", ($c1 & 070)>>3;
        } else {
            # Better be trailer!
            die "Invalid trailer code" unless $c1 == 0200;
	    # ($checksum & 07777) must equal last frame read.
            # $data has the checksum as read, which should not
	    # have been added in, but was.  Subtract it out.
	    $checksum -= ($data >> 6) + ($data&077);
            $checksum &= 07777;
            warn "Checksum error: $data <> $checksum\n" unless $data == $checksum;
	    print "\n";
	    last;
        }
    } else {
	# Location or Data -- get second byte of frame
	$c2 = getch(INPUT);
#warn "c2 $c2\n";
	die "$ARGV[0] low word has extra bits" if $c2 & 0300;
	# Update the checksum.
	$checksum = $checksum + $c1 + $c2;
	# Assemble the word.
	$c1 = ($c1 << 6) | $c2;
	# Location setting?
	if ($c1&010000) {
	    printf "%04o\n", $data if defined $data;
	    undef $data;
	    $loc = $c1 & 07777;
	    printf "%04o)", $loc;
	} else {
	    # Output of $data lags one behind, in case it's checksum, not data.
	    if (defined $data) {
		printf "%04o ", $data;
		$loc++;
		$loc &= 07777;
	    }
	    printf "\n%04o/", $loc if ($loc%010) == 0;
	    $data = $c1;
	}
    }
    # Start again with next byte.
    $c1 = getch(INPUT);
}
exit 0;