From: Lyndon Samson <lyndon.samson@...>
Date: 2005-10-24T13:29:37+09:00
Subject: Bit of fun II

More idle coding :-) A simple Compiler/Assembler/VM for a ( very basic
) RPN (dc) style language. I suspect its quite amenable to golfing,
but at a cost to readability.

def compile(pgm)
  outs = []

  lines = pgm.split("\n")
  lines.each { |line|
    tokens = line.strip.chomp.split(" ")
    pos = 0
    while true
      case tokens[pos]
        when '+'
          outs << "pop 1"
          outs << "pop 2"
          outs << "addr 1,2"
          outs << "push 1"
        when 'p'
          outs << "pop 1"
          outs << "print 1"
        when '',nil
        else
          outs << "loadr 1,#{tokens[pos]}"
          outs << "push 1"
      end

      pos = pos + 1
      break if pos > tokens.length
    end
  }

  return outs.join("\n")
end

def assemble(pgm)
  mem = []
  pc = 0

  lines = pgm.split("\n")
  lines.each { |line|
    tokens = line.strip.split(/ |,/)
    case tokens[0]
      when 'loadr'
        mem[pc]=1
        mem[pc+1]=tokens[1].to_i
        mem[pc+2]=tokens[2].to_i
        pc = pc+3
      when 'addr'
        mem[pc]=2
        mem[pc+1]=tokens[1].to_i
        mem[pc+2]=tokens[2].to_i
        pc = pc+3
      when 'print'
        mem[pc]=3
        mem[pc+1]=tokens[1].to_i
        pc = pc+2
      when 'push'
        mem[pc]=4
        mem[pc+1]=tokens[1].to_i
        pc = pc+2
      when 'pop'
        mem[pc]=5
        mem[pc+1]=tokens[1].to_i
        pc = pc+2
    end

  }

  mem.push(0)

  return mem
end

def execute(mem)
  pc = 0
  regs=[]
  stack=[]

  while true
    #puts "> PC:#{pc} CODE:#{mem[pc]} STACK:#{stack.join(',')}"

    case mem[pc]
      when 0
        break
      when 1
        regs[mem[pc+1]] = mem[pc+2]
        pc=pc+3
      when 2
        regs[mem[pc+1]] = regs[mem[pc+1]] + regs[mem[pc+2]]
        pc=pc+3
      when 3
        puts "#{regs[mem[pc+1]]}"
        pc=pc+2
      when 4  #push
        stack.push(regs[mem[pc+1]])
        pc=pc+2
      when 5  #pop
        regs[mem[pc+1]] = stack.pop()
        pc=pc+2
    end
  end

end

aapgm = compile("12 10 + 14 + p")
code = assemble(aapgm)

execute(code)


--
Into RFID? www.rfidnewsupdate.com Simple, fast, news.