#!/usr/bin/ruby

# whitepsace-asm
# Copyright (C) 2003 by Wayne E. Conrad
# 
# This library is free software; you can redistribute it and/or
# modify it under the terms of the GNU Lesser General Public
# License as published by the Free Software Foundation; either
# version 2 of the License, or (at your option) any later version.
# 
# This library 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
# Lesser General Public License for more details.
# 
# You should have received a copy of the GNU Lesser General Public
# License along with this library; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307  USA

class Assembler

  Opcodes = [
    ["  ", :push, :signed],
    [" \n ", :dup],
    [" \n\t", :swap],
    [" \n\n", :discard],
    ["\t   ", :add], 
    ["\t  \t", :sub],
    ["\t  \n", :mul],
    ["\t \t ", :div],
    ["\t \t\t", :mod],
    ["\t\t ", :store],
    ["\t\t\t", :retrieve],
    ["\n  ", :label, :unsigned],
    ["\n \t", :call, :unsigned],
    ["\n \n", :jump, :unsigned],
    ["\n\t ", :jz, :unsigned],
    ["\n\t\t", :jn, :unsigned],
    ["\n\t\n", :ret],
    ["\n\n\n", :exit],
    ["\t\n  ", :outchar],
    ["\t\n \t", :outnum],
    ["\t\n\t ", :readchar],
    ["\t\n\t\t", :readnum],
  ]

  def assemble(sourceName)
    destName = sourceName.chomp(".wsa") + ".ws"
    File.open(destName, "w") do |dest|
      @dest = dest
      File.open(sourceName, "r") do |source|
        @source = source
        for line in source
          line = line.strip.gsub(/#.*$/, "")
          next if line.empty?
          if line =~ /^(\d+):$/
            translate("label #{$1}")
          else
            translate(line)
          end
        end
      end
    end
  end

  private

  def error(message)
    puts "#{@source.path}:#{@source.lineno}: #{message}"
    exit 1
  end

  def encodeSignedNumber(n)
    (n >= 0 ? " " : "\t") + encodeUnsignedNumber(n.abs)
  end

  def encodeUnsignedNumber(n)
    ("%b" % n).tr("01", " \t") + "\n"
  end

  def translate(line)
    for ws, opcode, arg in Opcodes
      r = "^#{opcode}"
      if arg
        r << '\s+('
        r << '(-|\+)?' if arg == :signed
        r << '\d+)'
      end
      r << '$'
      if line =~ Regexp.new(r)
        @dest.print ws
        case arg
        when :signed
          @dest.print encodeSignedNumber($1.to_i)
        when :unsigned
          @dest.print encodeUnsignedNumber($1.to_i)
        end
      end
    end
  end

end

for sourceName in ARGV
  Assembler.new.assemble(sourceName)
end