Class: Gruesome::Z::Processor

Inherits:
Object
  • Object
show all
Defined in:
lib/gruesome/z/processor.rb

Instance Method Summary collapse

Constructor Details

#initialize(memory) ⇒ Processor

Returns a new instance of Processor.



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# File 'lib/gruesome/z/processor.rb', line 14

def initialize(memory)
  @memory = memory
  @header = Header.new(@memory.contents)
  @abbreviation_table = AbbreviationTable.new(@memory)
  @object_table = ObjectTable.new(@memory)
  @dictionary = Dictionary.new(@memory)
end

Instance Method Details

#branch(branch_to, branch_on, result) ⇒ Object 



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# File 'lib/gruesome/z/processor.rb', line 70

def branch(branch_to, branch_on, result)
  if (result == branch_on)
    if branch_to == 0
      routine_return(0)
    elsif branch_to == 1
      routine_return(1)
    else
      @memory.program_counter = branch_to
#            @memory.program_counter -= 2
    end
  end
end

#execute(instruction) ⇒ Object 



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# File 'lib/gruesome/z/processor.rb', line 83

def execute(instruction)
  # Pull values from the variables if needed by the instruction
  # there are some exceptions for variable-by-reference instructions
  operands = instruction.operands.each_with_index.map do |operand, idx|
    if idx == 0 and Opcode.is_variable_by_reference?(instruction.opcode, @header.version)
      operand
    elsif instruction.types[idx] == OperandType::VARIABLE
      @memory.readv(operand)
    else
      operand
    end
  end

  case instruction.opcode
  when Opcode::ART_SHIFT
    places = unsigned_to_signed(operands[1])
    if places < 0
      @memory.writev(instruction.destination, unsigned_to_signed(operands[0]) >> places.abs)
    else
      @memory.writev(instruction.destination, operands[0] << places)
    end
  when Opcode::CALL, Opcode::CALL_1N
    routine_call(@memory.packed_address_to_byte_address(operands[0]), operands[1..-1], instruction.destination)
  when Opcode::CLEAR_ATTR
    @object_table.object_clear_attribute(operands[0], operands[1])
  when Opcode::DEC
    @memory.writev(operands[0], unsigned_to_signed(@memory.readv(operands[0])) - 1)
  when Opcode::INC
    @memory.writev(operands[0], unsigned_to_signed(@memory.readv(operands[0])) + 1)
  when Opcode::INC_CHK
    new_value = unsigned_to_signed(@memory.readv(operands[0])) + 1
    @memory.writev(operands[0], new_value)
    result = new_value > unsigned_to_signed(operands[1])
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::DEC_CHK
    new_value = unsigned_to_signed(@memory.readv(operands[0])) - 1
    @memory.writev(operands[0], new_value)
    result = new_value < unsigned_to_signed(operands[1])
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::INSERT_OBJ
    @object_table.object_insert_object(operands[1], operands[0])
  when Opcode::GET_CHILD
    child = @object_table.object_get_child(operands[0])
    @memory.writev(instruction.destination, child)
    result = child != 0
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::GET_NEXT_PROP
    next_prop = @object_table.object_get_next_property(operands[0], operands[1])
    @memory.writev(instruction.destination, next_prop)
  when Opcode::GET_PARENT
    parent = @object_table.object_get_parent(operands[0])
    @memory.writev(instruction.destination, parent)
  when Opcode::GET_PROP
    prop = @object_table.object_get_property_word(operands[0], operands[1])
    @memory.writev(instruction.destination, prop)
  when Opcode::GET_PROP_ADDR
    prop = @object_table.object_get_property_addr(operands[0], operands[1])
    @memory.writev(instruction.destination, prop)
  when Opcode::GET_PROP_LEN
    if operands[0] == 0
      result = 0
    else
      result = @object_table.object_get_property_data_size_from_address(operands[0])
    end
    @memory.writev(instruction.destination, result)
  when Opcode::GET_SIBLING
    sibling = @object_table.object_get_sibling(operands[0])
    @memory.writev(instruction.destination, sibling)
    result = sibling != 0
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::JUMP, Opcode::PIRACY
    @memory.program_counter += unsigned_to_signed(operands[0])
    @memory.program_counter -= 2
  when Opcode::JE
    result = operands[1..-1].inject(false) { |result, element|
      result | (operands[0] == element)
    }
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::JG
    result = operands[1..-1].inject(false) { |result, element|
      result | (unsigned_to_signed(operands[0]) > unsigned_to_signed(element))
    }
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::JIN
    result = @object_table.object_get_parent(operands[0]) == operands[1]
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::JL
    result = operands[1..-1].inject(false) { |result, element|
      result | (unsigned_to_signed(operands[0]) < unsigned_to_signed(element))
    }
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::JZ
    result = operands[0] == 0
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::LOAD
    if operands[0] != instruction.destination
      @memory.writev(instruction.destination, @memory.readv(operands[0]))

      # make sure to re-push the value since LOAD does not
      # change the stack but uses the value directly
      if operands[0] == 0
        @memory.writev(0, @memory.readv(instruction.destination))
      end
    end
  when Opcode::LOADB
    @memory.writev(instruction.destination, @memory.readb(operands[0] + unsigned_to_signed(operands[1])))
  when Opcode::LOADW
    @memory.writev(instruction.destination, @memory.readw(operands[0] + unsigned_to_signed(operands[1])*2))
  when Opcode::LOG_SHIFT
    places = unsigned_to_signed(operands[1])
    if places < 0
      @memory.writev(instruction.destination, operands[0] >> places.abs)
    else
      @memory.writev(instruction.destination, operands[0] << places)
    end
  when Opcode::NOP
  when Opcode::NEW_LINE
    puts  
  when Opcode::POP
    # get rid of the first item on stack
    @memory.readv(0)
  when Opcode::PRINT
    print operands[0]
  when Opcode::PRINT_ADDR
    print ZSCII.translate(0, @header.version, @memory.force_readzstr(operands[0])[1], @abbreviation_table)
  when Opcode::PRINT_CHAR
    print ZSCII.translate_Zchar(operands[0])
  when Opcode::PRINT_NUM
    print unsigned_to_signed(operands[0]).to_s
  when Opcode::PRINT_OBJ
    print @object_table.object_short_text(operands[0])
  when Opcode::PRINT_PADDR
    str_addr = @memory.packed_address_to_byte_address(operands[0])
    print ZSCII.translate(0, @header.version, @memory.force_readzstr(str_addr)[1], @abbreviation_table)
  when Opcode::PRINT_RET
    puts operands[0]
    routine_return(1)
  when Opcode::PULL
    if @header.version == 6
      # TODO: Version 6 PULL instruction
      #
      # stack to pull from is given as operand[0]
      # instruction.destination is the destination resister
    else
      # pop value from stack
      @memory.writev(operands[0], @memory.readv(0))
    end
  when Opcode::PUSH
    # add value to stack
    @memory.writev(0, operands[0])
  when Opcode::PUT_PROP
    object_id = operands[0]
    prop_id = operands[1]
    prop_value = operands[2]

    @object_table.object_set_property_word(object_id, prop_id, prop_value)
  when Opcode::RANDOM
    value = unsigned_to_signed(operands[0])
    if value < 0
      # seed with value
      srand(value)
      result = 0
    elsif value == 0
      # seed with timestamp
      srand()
      result = 0
    else
      # pull random number from between 1 and value
      result = rand(value-1) + 1
    end
    @memory.writev(instruction.destination, result)
  when Opcode::REMOVE_OBJ
    @object_table.object_remove_object(operands[0])
  when Opcode::RESTORE
    if @header.version <= 4
      @memory.restore
      if @header.version >= 4
        @memory.writev(instruction.destination, 1)
      end
      branch(instruction.branch_to, instruction.branch_on, true)
    end
  when Opcode::RET
    routine_return(operands[0])
  when Opcode::RET_POPPED
    routine_return(@memory.readv(0))
  when Opcode::RTRUE
    routine_return(1)
  when Opcode::RFALSE
    routine_return(0)
  when Opcode::SAVE
    if @header.version <= 4
      @memory.save
      if @header.version >= 4
        @memory.writev(instruction.destination, 1)
      end
      branch(instruction.branch_to, instruction.branch_on, true)
    end
  when Opcode::SET_ATTR
    @object_table.object_set_attribute(operands[0], operands[1])
  when Opcode::SREAD
    # read the maximum number of bytes in the text-buffer
    max_bytes = @memory.force_readb(operands[0])

    # address of the next byte in the text-buffer
    addr = operands[0] + 1

    # read in a line of input from stdin
    line = $stdin.readline[0..-2]

    # truncate line to fit the max characters given by text-buffer
    if line.length > max_bytes
      line = line[0..max_bytes]
    end

    # tokenize
    lexed = @dictionary.tokenize(line)

    # parse
    parsed = @dictionary.parse(lexed)

    # encode the line into a ZChar stream
    str = ZSCII.encode_to_zchars(line, @header.version)

    # write the text to the text-buffer
    num_bytes = 1
    first_position = 1
    if @header.version >= 5
      num_bytes += 1
      @memory.force_writeb(addr, line.length)
      first_position = 2
      addr += 1
    end

    str.each do |zchr|
      num_bytes += 1
      if num_bytes > max_bytes
        break
      end
      @memory.force_writeb(addr, zchr)
      addr += 1
    end

    if @header.version < 5
      # terminator
      if num_bytes <= max_bytes
        @memory.force_writeb(addr, 0)
      end
    end

    # write the parse-buffer
    max_bytes = @memory.force_readb(operands[1])
    max_bytes = 2 + max_bytes * 4
    addr = operands[1] + 1
    num_bytes = 1

    if num_bytes <= max_bytes
      @memory.force_writeb(addr, lexed.length)
      addr += 1
    end

    parsed.each do |token, index|
      num_bytes += 4
      if num_bytes > max_bytes
        break
      end
      @memory.force_writew(addr, token[:address])
      addr += 2
      @memory.force_writeb(addr, token[:size])
      addr += 1
      @memory.force_writeb(addr, token[:position]+first_position)
      addr += 1
    end
  when Opcode::TEST
    result = (operands[0] & operands[1]) == operands[1]
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::TEST_ATTR
    result = @object_table.object_has_attribute?(operands[0], operands[1])
    branch(instruction.branch_to, instruction.branch_on, result)
  when Opcode::ADD
    @memory.writev(instruction.destination,
      unsigned_to_signed(operands[0]) + unsigned_to_signed(operands[1]))
  when Opcode::SUB
    @memory.writev(instruction.destination,
      unsigned_to_signed(operands[0]) - unsigned_to_signed(operands[1]))
  when Opcode::MUL
    @memory.writev(instruction.destination,
      unsigned_to_signed(operands[0]) * unsigned_to_signed(operands[1]))
  when Opcode::DIV
    result = unsigned_to_signed(operands[0]).to_f / unsigned_to_signed(operands[1]).to_f
    if result < 0
      result = -(result.abs.floor)
    else
      result = result.floor
    end
    @memory.writev(instruction.destination, result.to_i)
  when Opcode::MOD
    a = unsigned_to_signed(operands[0])
    b = unsigned_to_signed(operands[1])
    result = a.abs % b.abs
    if a < 0 
      result = -result
    end
    @memory.writev(instruction.destination, result.to_i)
  when Opcode::NOT
    @memory.writev(instruction.destination, ~(operands[0]))
  when Opcode::OR
    @memory.writev(instruction.destination, operands[0] | operands[1])
  when Opcode::AND
    @memory.writev(instruction.destination, operands[0] & operands[1])
  when Opcode::STORE
    if operands[0] == 0
      @memory.readv(operands[0])
    end
    @memory.writev(operands[0], operands[1])
  when Opcode::STOREB
    @memory.writeb(operands[0] + unsigned_to_signed(operands[1]), operands[2])
  when Opcode::STOREW
    @memory.writew(operands[0] + unsigned_to_signed(operands[1])*2, operands[2])
  else
    puts instruction.opcode
    raise "opcode " + Opcode.name(instruction.opcode, @header.version) + " not implemented"
  end
end

#routine_call(address, arguments, result_variable = nil) ⇒ Object 



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# File 'lib/gruesome/z/processor.rb', line 22

def routine_call(address, arguments, result_variable = nil)
  if address == 0
    # special case, do not call, simply return false
    if result_variable != nil
      @memory.writev(result_variable, 0)
    end
  else
    return_addr = @memory.program_counter
    @memory.program_counter = address

    # read routine
    num_locals = @memory.force_readb(@memory.program_counter)
    @memory.program_counter += 1

    # create environment
    @memory.push_routine(return_addr, num_locals, result_variable)

    if @header.version <= 4
      # read initial values when version 1-4
      (1..num_locals).each do |i|
        @memory.writev(i, @memory.force_readw(@memory.program_counter))
        @memory.program_counter += 2
      end
    else
      # reset local vars to 0
      (1..num_locals).each do |i|
        @memory.writev(i, 0)
      end
    end

    # copy arguments over into locals
    idx = 1
    arguments.each do |i|
      @memory.writev(idx, i)
      idx += 1
    end
  end
end

#routine_return(result) ⇒ Object 



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# File 'lib/gruesome/z/processor.rb', line 61

def routine_return(result)
  frame = @memory.pop_routine

  if frame[:destination] != nil
    @memory.writev(frame[:destination], result)
  end
  @memory.program_counter = frame[:return_address]
end