# File voodoo/generators/i386_nasm_generator.rb, line 43
def initialize params = {}
  # Number of bytes in a word
  @WORDSIZE_BITS = 2
  @WORDSIZE = 1 << @WORDSIZE_BITS
  # Word name in NASM lingo
  @WORD_NAME = 'dword'
  # Default alignment for code
  @CODE_ALIGNMENT = 0
  # Default alignment for data
  @DATA_ALIGNMENT = @WORDSIZE
  # Default alignment for functions
  @FUNCTION_ALIGNMENT = 16
  # Stack alingment
  @STACK_ALIGNMENT_BITS = @WORDSIZE_BITS
  @STACK_ALIGNMENT = 1 << @STACK_ALIGNMENT_BITS
  # Register used for return values
  @RETURN_REG = :eax
  # Accumulator index
  @AX = :eax
  # Base index
  @BX = :ebx
  # Count index
  @CX = :ecx
  # Data index
  @DX = :edx
  # Base pointer
  @BP = :ebp
  # Stack pointer
  @SP = :esp
  # Registers used to store locals
  @LOCAL_REGISTERS = []
  @NLOCAL_REGISTERS = @LOCAL_REGISTERS.length
  @LOCAL_REGISTERS_SET = Set.new @LOCAL_REGISTERS
  @SAVE_FRAME_REGISTERS = [:ebx, :edi, :esi, :esp, :ebp]
  @SAVED_FRAME_LAYOUT = {}
  @SAVE_FRAME_REGISTERS.each_with_index { |r,i| @SAVED_FRAME_LAYOUT[r] = i }
  @TEMPORARIES = [:ebx]
  super params
  @saved_registers = []
  in_section(:data) { emit "extern _GLOBAL_OFFSET_TABLE_\n" }
  @features.merge!          :'bits-per-word' => '32',
    :'byte-order' => 'little-endian',
    :'bytes-per-word' => '4'
end

# File voodoo/generators/i386_nasm_generator.rb, line 90
def arg_offset n
  8 + (n * @WORDSIZE)
end

# File voodoo/generators/i386_nasm_generator.rb, line 95
def begin_function formals, nlocals
  environment = Environment.new @environment
  @environment = environment
  emit "push #{@BP}\nmov #{@BP}, #{@SP}\n"
  formals.each_with_index do |arg,i|
    environment.add_arg arg, arg_offset(i)
  end
  emit "sub #{@SP}, #{nlocals * @WORDSIZE}\n"      
end

# File voodoo/generators/i386_nasm_generator.rb, line 106
def call func, *args
  revargs = args.reverse
  revargs.each { |arg| push arg }
  use_value "call", func
  if args.length > 0
    emit "add esp, #{@WORDSIZE * args.length}\n"
  end
end

# File voodoo/generators/i386_nasm_generator.rb, line 116
def load_got_address reg
  lbl = gensym
  emit "call #{lbl}\n"
  emit "#{lbl}:\n"
  emit "pop #{reg}\n"
  emit "add #{reg}, _GLOBAL_OFFSET_TABLE_ + $$ - #{lbl} wrt ..gotpc\n"
  reg
end

# File voodoo/generators/i386_nasm_generator.rb, line 126
def load_symbol_from_got symbol, reg
  load_got_address reg
  emit "mov #{reg}, [#{reg} + #{symbol} wrt ..got]\n"
  reg
end

# File voodoo/generators/i386_nasm_generator.rb, line 134
def local_offset_or_register n
  (n + 1) * -@WORDSIZE
end

# File voodoo/generators/i386_nasm_generator.rb, line 139
def push value
  value_ref = load_value value, "ebx"
  emit "push dword #{value_ref}\n"
end

# File voodoo/generators/i386_nasm_generator.rb, line 145
def tail_call fun, *args
  if args.length > @environment.args
    # Not enough space to do proper tail call; do normal call instead
    emit "; not enough space for proper tail call; changed to regular call\n"
    ret :call, fun, *args
  else
    # If any arguments are going to be overwritten before they are
    # used, save them to new local variables and use those instead.
    (args.length - 1).downto(0) do |i|
      arg = args[i]
      next unless symbol?(arg)
      old_arg_offset = @environment[arg]
      next if old_arg_offset == nil || old_arg_offset < 0
      # arg is an argument that was passed on the stack.
      new_arg_offset = arg_offset i
      next unless old_arg_offset > new_arg_offset
      # arg will be overwritten before it is used.
      # Save it in a newly created temporary variable,
      # then use that instead.
      newsym = @environment.gensym
      let newsym, arg
      args[i] = newsym
    end

    # Same for the function we will be calling.
    if symbol?(fun)
      offset = @environment[fun]
      if offset != nil && offset > 0
        newsym = @environment.gensym
        let newsym, fun
        func = newsym
      end
    end

    # Set arguments
    if args.length > 0
      (args.length - 1).downto(0).each do |i|
        arg = args[i]
        
        value_ref = load_value arg, :eax
        newarg_ref = "[ebp + #{arg_offset i}]"
        # Elide code if source is same as destination
        unless value_ref == newarg_ref
          if memory_operand?(value_ref)
            emit "mov eax, #{value_ref}\n"
            value_ref = :eax
          end
          emit "mov #{@WORD_NAME} #{newarg_ref}, #{value_ref}\n"
        end
      end
    end

    # Tail call
    emit "mov esp, ebp\npop ebp\n"
    use_value "jmp", fun
  end
end

# File voodoo/generators/i386_nasm_generator.rb, line 203
def use_value operation, value
  value_ref = load_value value, :eax
  emit "#{operation} #{value_ref}\n"
end

# File voodoo/generators/i386_nasm_generator.rb, line 209
def word value
  emit "dd #{value}\n"
end