#!/usr/bin/perl

#
# Read a .ls or .lst file, and attempt to
# re-create the original source.
#

#
# Known bugs:
#

$of = $ARGV[0];
$of =~ s/.lst$/.pal/;
$of =~ s/.ls$/.pa/;
die "list file?: $of" if $of eq $ARGV[0];

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

$nl = 0; # No blank lines seen yet
while (<INPUT>) {
  s/\r//;	# Remove CR, if any
  chop;		# Remove LF
  s/\f//;	# Remove FF
# Page zero literals are output after the '$'
# which terminates the program.  This means
# they won't be output here.
#print "*$1;$2\n" if /(\d+)\s+(\d+)/;
  if ($_ eq "") {
#warn "blank\n";
    $nl++;
    next;
  }
  # This line is non-blank. Maybe it is a page header?
  if (/PAL8.*PAGE/) {
#warn "header\n";
    # Ignore previous blank lines, and set up to
    # ignore the blank line which follows.
    $nl = -1;
    next;
  }
  # Not a page header, so preserve the blank lines
  # preceding it (if any).
  while ($nl > 0) {
#warn "saved nl\n";
    print OUTPUT "\r\n";
    $nl--;
  }
  if (s/^\d+\s+\d+['\s]//) {
#warn "program data\n";
    # Output it without line number or octal content
# TODO: Save the octal elsewhere??
    s/^\s+//;	# Lose leading spaces
    # Two cases, it contains a comma, or it doesn't.
    if (m:^[^/]+,:) {
      s/,\s+/,\t/; # Convert to tab, preserves alignment
    } else {
      print OUTPUT "\t";
    }
    print OUTPUT $_, "\r\n";
    $nl = 0;
    next;
  }
  # Comments are just output as is.
  # Note: Spaces before the /, if any, are elided.
  if (s:\s+/:/:) {
#warn "comment\n";
    print OUTPUT $_, "\r\n";
    $nl = 0;
    next;
  }
  # Multi-word output in the listing is elided.
  next if /^\d+\s+\d+\s*$/;
  # The "$" indicates the end of the program.
  # Exit so that we don't try to process the
  # symbol table.
  if (s:\s+\$:\$:) {
#warn "end\n";
    print OUTPUT $_, "\r\n";
    exit 0;
  }
  # Some lines don't generate stored code,
  # but do get an octal number in front.
  if (s/\s+\d+\s\s//) {
#warn "nocode\n";
    s/\s+// unless /^\s\s\s/;
    print OUTPUT $_, "\r\n";
    $nl = 0;
    next;
  }
  # Some lines don't generate code, but should be
  # output anyway. (Comments, ifdef stuff, etc.)
  # We don't know how much leadint whitespace
  # to remove, so we remove it all.
  if (s:\s+::) {
#warn "comment\n";
    print OUTPUT $_, "\r\n";
    $nl = 0;
    next;
  }
}