Class: C64Asm::Basic

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

Overview

C64 Basic block

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(program, origin = 0x801, align = true) ⇒ Basic

Create a new C64 basic block

Raises:



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# File 'lib/c64asm/basic.rb', line 18

def initialize(program, origin = 0x801, align = true)
  raise BasicError, 'Program has to be a string' unless program.instance_of? String
  raise BasicError, 'Origin has to be a fixnum' unless origin.instance_of? Fixnum
  raise BasicError, 'Origin out of range' unless (origin >= 0 and origin <= 65535)

  @basic = program
  @code = Block.new

  @code.push(Align.new(origin)) if align
  @code.push(Data.new(parse(origin)))
end

Instance Attribute Details

#basic ⇒ Object (readonly)

Returns the value of attribute basic.



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# File 'lib/c64asm/basic.rb', line 15

def basic
  @basic
end

#code ⇒ Object (readonly)

Returns the value of attribute code.



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# File 'lib/c64asm/basic.rb', line 15

def code
  @code
end

Instance Method Details

#parse(addr) ⇒ Object (private)

Parse basic code string given the origin address



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# File 'lib/c64asm/basic.rb', line 35

def parse(addr)
  state = :nextline
  bytes = []
  line = []
  token = ''

  @basic.upcase.each_char do |c|
    if c == "\n"
      state = :nextline
      next
    end

    if state == :nextline
      unless token.empty?
        token.codepoints.each{|p| bytes += [PETSCII[p]]}
        token = ''
      end

      unless bytes.empty?
        bytes += [0]
        addr += 1
      end

      addr += 2
      bytes += [addr.ls_byte, addr.ms_byte]
      state = :linenum
    end

    if state == :linenum
      if c.match(/\d/)
        token += c
        addr += 1
      else
        raise BasicError, 'Each line has to start with a line number' if token.empty?

        lineno = token.to_i
        raise BasicError, 'Line number out of range' unless (lineno >= 0 and lineno <= 65535)

        bytes += [lineno.ls_byte, lineno.ms_byte]
        addr += 2
        state = :out
        token = ''

        next if c == ' '
      end
    end

    if state == :out
      if c == '"'
        bytes += [PETSCII['"'.ord]]
        addr += 1
        state = :in

        next
      elsif c == ' '
        unless token.empty?
          token.codepoints.each{|p| bytes += [PETSCII[p]]}
          token = ''
        end

        bytes += [PETSCII[' '.ord]]
        addr += 1
      elsif BASIC.has_key? c
        token.codepoints.each{|p| bytes += [PETSCII[p]]} unless token.empty?
        bytes += [BASIC[c]]
        addr += 1
        token = ''
      else
        raise BasicError, 'Unknown character' unless PETSCII.has_key? c.codepoints.to_a.first

        token += c
        addr += 1

        if BASIC.has_key? token
          bytes += [BASIC[token]]
          token = ''
        end
      end
    end

    if state == :in
      raise BasicError, 'Unknown character' unless PETSCII.has_key? c.codepoints.to_a.first

      token += c
      addr += 1
      state = :out if c == '"'
    end
  end

  unless token.empty?
    token.codepoints.each{|p| bytes += [PETSCII[p]]}
    bytes += [0]
  end

  bytes += [0, 0]
end

#to_s ⇒ Object

Return a pretty string representation



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# File 'lib/c64asm/basic.rb', line 31

def to_s; "<Basic: #{@basic.lines.to_a.length}>"; end