Class: C64Asm::Block

Inherits:
Array
  • Object
show all
Defined in:
lib/c64asm/asm.rb

Overview

Block is a raw machine code block Implements the non-magic of linking, aka symbol resolution.

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ Block

Create new block



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# File 'lib/c64asm/asm.rb', line 441

def initialize
  @labels = {}
  @linked = false
  @chunks = {}
end

Instance Attribute Details

#labels ⇒ Object (readonly)

Returns the value of attribute labels.



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# File 'lib/c64asm/asm.rb', line 438

def labels
  @labels
end

#linked ⇒ Object (readonly)

Returns the value of attribute linked.



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# File 'lib/c64asm/asm.rb', line 438

def linked
  @linked
end

Instance Method Details

#binary_pass ⇒ Object

Internal method, treat as private



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# File 'lib/c64asm/asm.rb', line 548

def binary_pass
  binary = ''
  each do |e|
    case e
    when Align
      binary += ([0] * (e.addr - @chunks[e.addr])).pack('C*')
    when Label
      true
    when Data
      binary += e.to_binary
    when Operand
      binary += e.to_binary
    when Block
      binary += e.binary_pass
    end
  end

  binary
end

#dump ⇒ Object

Return verbose representation



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# File 'lib/c64asm/asm.rb', line 481

def dump
  link unless @linked
  lines = dump_pass
  lines.shift
  lines
end

#dump_pass ⇒ Object

Internal method, treat as private



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# File 'lib/c64asm/asm.rb', line 506

def dump_pass
  addr = @linked.first
  lines = []

  lines.push('$%0.4x   ' % addr +  "           \t.block")
  each do |e|
    line = ('$%0.4x   ' % addr).upcase
    block = false

    case e
    when Operand
      if e.mode == :r
        bytes = e.to_a.pack('Cc').unpack('C*')
      else
        bytes = e.to_a
      end
      line += bytes.to_a.collect{|e| '%0.2X' % e}.join(' ')
      line += ' ' * (9 - (3 * e.length))
      line += "   \t#{e.to_source}"
      addr += e.length
    when Align
      line += "           \t#{e.to_source}"
      addr = e.addr
    when Label
      line += "           #{e.to_source}"
    when Data
      line += ".. .. ..   \t#{e.to_source}"
      addr += e.length
    when Block
      addr, lines_passed = e.dump_pass
      lines += lines_passed
      block = true
    end

    lines.push(line) unless block
  end
  lines.push('$%0.4x   ' % addr +  "           \t.bend")

  [addr, lines]
end

#link(origin = 0x1000) ⇒ Object

Link resolves symbols and relative jumps given the origin

Raises:



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# File 'lib/c64asm/asm.rb', line 448

def link(origin = 0x1000)
  raise BlockError, 'Invalid origin' unless (origin >= 0 and origin <= 65535)

  # override origin if first non-Block element is an Align object
  felem = first
  while felem.class == Block
    felem = felem.first
  end
  if felem.instance_of? Align
    origin = felem.addr
  end

  endaddr = linker_pass(origin, :one)
  linker_pass(origin, :two)

  @linked
end

#linker_pass(addr, pass) ⇒ Object

Internal method, treat as private



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# File 'lib/c64asm/asm.rb', line 569

def linker_pass(addr, pass)
  @labels = {} if pass == :one
  origin = addr

  each do |e|
    case e
    when Align
      raise BlockError, "Invalid alignment from $#{addr.to_s(16)} to $#{e.addr.to_s(16)}" if e.addr < addr

      @chunks[e.addr] = addr if pass == :one
      addr = e.addr
    when Label
      if pass == :one
        if @labels.has_key? e.name
          C64Asm.log :warn, "Redefinition of label #{e.name} from $#{@labels[e.name].to_s(16)} to $#{addr.to_s(16)}"
        end

        @labels[e.name] = addr
      end
    when Data
      addr += e.length
    when Operand
      if pass == :two
        unless e.ready?
          if e.label == :*
            arg = addr
          elsif @labels.has_key? e.label
            arg = @labels[e.label]
          else
            C64Asm.log :error, "Can't resolve label for #{e.to_s}"
            raise BlockError
          end

          if e.mode == :r
            arg = arg - addr -2
          end

          e.resolve(arg)
        end
      end

      addr += e.length
    when Block
      addr = e.linker_pass(addr, pass)
    else
      C64Asm.log :error, "Invalid element #{e.to_s} in Block"
      raise BlockError
    end
  end

  @linked = [origin, addr] if pass == :one
  addr
end

#to_binary ⇒ Object

Turn block into byte string



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# File 'lib/c64asm/asm.rb', line 475

def to_binary
  link unless @linked
  [@linked[0].ls_byte, @linked[0].ms_byte].pack('CC') + binary_pass
end

#to_s ⇒ Object

Return pretty string representation



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# File 'lib/c64asm/asm.rb', line 472

def to_s; "<Block #{length}>"; end

#to_source ⇒ Object

Return source code representation



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# File 'lib/c64asm/asm.rb', line 467

def to_source
  (['.block'] + collect{|e| e.to_source} + ['.bend']).flatten
end

#write!(fname, mode = 'w', what = :prg) ⇒ Object

Write block to a given file in the given format This will probably overwrite the target file without warning.



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# File 'lib/c64asm/asm.rb', line 490

def write!(fname, mode = 'w', what = :prg)
  File.open(fname, mode) do |fd|
    case what
    when :prg
      fd.write(to_binary)
    when :src
      fd.write(to_source.join("\n"))
    when :dump
      fd.write(dump.join("\n"))
    else
      raise BlockError, 'Unknown generation mode'
    end
  end
end