assem.sml

structure Assem = struct

  type reg = string
  type temp = Temp.temp
  type label = Temp.label

  datatype instr = OPER of {assem: string,
			                      dst: temp list,
			                      src: temp list,
			                      jump: label list option}
                 | LABEL of {assem: string, lab: Temp.label}
                 | MOVE of {assem: string,
			                      dst: temp,
			                      src: temp}

  fun format saytemp =
    let fun speak(assem,dst,src,jump) =
      let val saylab = Symbol.name
        fun f(#"`":: #"s":: i::rest) =
		        (explode(saytemp(List.nth(src,ord i - ord #"0"))) @ f rest)
		      | f( #"`":: #"d":: i:: rest) =
		        (explode(saytemp(List.nth(dst,ord i - ord #"0"))) @ f rest)
		      | f( #"`":: #"j":: i:: rest) =
		        (explode(saylab(List.nth(jump,ord i - ord #"0"))) @ f rest)
		      | f( #"`":: #"`":: rest) = #"`" :: f rest
		      | f( #"`":: _ :: rest) = ErrorMsg.impossible "bad Assem format"
		      | f(c :: rest) = (c :: f rest)
		      | f nil = nil
	    in implode(f(explode assem))
	    end
    in fn OPER{assem,dst,src,jump=NONE} => speak(assem,dst,src,nil)
        | OPER{assem,dst,src,jump=SOME j} => speak(assem,dst,src,j)
	      | LABEL{assem,...} => assem
	      | MOVE{assem,dst,src} => speak(assem,[dst],[src],nil)
    end
end