#!/usr/bin/perl -w

# By Jeff Winston  http://www.kwcpa.com/tools
# Rev. 1.0 3/30/09 Copyright (C) 2009
# 
# MODSPLIT splits verilog modules into files with a single module per file
# and the a filename that matches the module name
# 
# Type modsplit.pl (no arguments) for more information
# 
# ---------------------------------------------------------------------
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License
# as published by the Free Software Foundation; either version 2
# of the License, or (at your option) any later version.
# 
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
# 
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
# USA.  or check out http://www.gnu.org/copyleft/gpl.html
# ---------------------------------------------------------------------

$| = 1; # enable autoflush

# parse command line
if (($#ARGV != 1) && ($#ARGV != 2)) {
    print_help();
    exit(0);
}

$input_filename = shift @ARGV;
$output_folder = shift @ARGV;

#optional header file
@header =();
if ($#ARGV != -1) {
    $header_filename = shift @ARGV;
    if (!(-e $header_filename)) {
	print "Error: No such file $header_filename\n";
	exit(1);
    } 
    @header = `cat $header_filename`;
}

#inits
@inter_mod_lines=();
$write=0;
$open=0;

#open and parse input file
open(INFIL,  "< $input_filename")  or die "Could not open $input_filename";

while(defined($line = <INFIL>)) {
    chomp $line;

    $#words = -1;
    if (length($line)>5) {
	@words = split " ",$line;
    }
    # module keyword starts module
    if (($#words > -1) && ($words[0] eq "module")) {
	if ($write == 1) {
	    print "Error: Module definition found within module on line: $line\n";
	    exit(1);
	}
	$write = 1;
	@words = split " ",$line;
	$filename = $output_folder . "/" . $words[1] . ".v";
	if ($open == 1) {
	    close (OUTFIL);
	}
	open (OUTFIL, "> $filename") or die "Error: Could not open $filename...exiting";
	$open=1;
	print "Opening $filename...";

	# print intermod lines if any
	dump_inter_mod_lines();

	# copy header
	if ($#header > -1) {
	    foreach $line (@header) {
		print OUTFIL $line;
	    }
	}

        # print first line of module
	print OUTFIL "$line\n";
    }

    # endmodule keyword ends module
    elsif (($#words > -1) && ($words[0] eq "endmodule")) {
	if ($write == 0) {
	    print "Error: Extra endmodule found outside of module on line: $line\n";
	    exit(1);
	}
	$write = 0;
	print OUTFIL "$line\n";
	print "written\n";
    }

    # otherwise if in module just print line
    elsif ($write == 1) {
	print OUTFIL "$line\n";
    }
    #otherwise - collect intermodule lines
    else {
	if (length($line) > 0) {
	    push @inter_mod_lines, $line;

	    # dump at endif
	    if ($line =~ "\`endif") {
		if ($open == 1) {
		    dump_inter_mod_lines();
		}
	    }
	}
    }
}
# dump at end
if ($open == 1) {
    dump_inter_mod_lines();
    close (OUTFIL);
}
exit(0);

sub dump_inter_mod_lines {
    foreach $line (@inter_mod_lines) {
	print OUTFIL "$line\n";
    }
    @inter_mod_lines=();
}

sub print_help {
    print "\nUsage:  modsplit.pl <input filename> <output directory> [<header filename>] \n";
    print "Where the optional <header filename> is a header which can be attached to the top of every file.\n\n";
    print "Modsplit will take any verilog file and parse for module definitions.  It will write each module\n";
    print "into an output file having the same name as the module.  It tries to be smart about lines that are\n";
    print "outside module definitions.  Typically, it prepends them to the next module.  However, if it\n";
    print "encounters an `endif, the lines before the `endif will stay with the prior module.\n\n";
}