(* high-to-mid.sml
 *
 * COPYRIGHT (c) 2010 The Diderot Project (http://diderot.cs.uchicago.edu)
 * All rights reserved.
 *
 * Translation from HighIL to MidIL representations.
 *)

structure HighToMid : sig

    val translate : HighIL.program -> MidIL.program

  end = struct

    structure SrcIL = HighIL
    structure SrcOp = SrcIL.Op
    structure DstIL = MidIL
    structure DstOp = DstIL.Op
    structure VMap = SrcIL.Var.Map

  (* expand the field Inside operator into a image-space test *)
    fun expandInside (env, result, pos, fld) = let
	  val pos' = lookupVar (env, pos)
	  val fld = (case valueOf fld
		 of SrcIL.OP(SrcOp.Field fld, []) => fld
		  | _ => raise Fail "bogus field binding"
		(* end case *))
	  fun expand (FieldDef.CONV(_, img, _)) => let
		val imgPos = newVar ??
		in [
		  (imgPos, DstIL.OP(DstOp.Transform img, [pos'])),
		  (result, DstIL.OP(DstOp.Inside img, [imgPos]))
		] end
	    | expand (FieldDef.NEG fld) => expand fld
	    | expand (FieldDef.SUM(fld1, dlf2)) => raise Fail "expandInside: SUM"
	  in
	    expand fld
	  end

    fun expandProbe (env, result, fld, pos) = let
	  val pos' = lookupVar (env, pos)
	  val fld = (case valueOf fld
		 of SrcIL.OP(SrcOp.Field fld, []) => fld
		  | _ => raise Fail "bogus field binding"
		(* end case *))
	  fun expand (result, FieldDef.CONV(0, img, h)) => let
		val imgPos = newVar ??
		val xformStm = (imgPos, DstIL.OP(DstOp.Transform img, [pos']))
(* generate samples based on kernel support and dimensionality of image *)
		in
		  xformStm :: probeStms
		end
	    | expand (FieldDef.CONV(k, img, h)) => ??
	    | expand (FieldDef.NEG fld) => let
		val r = newVar ??
		val stms = expand (r, fld)
		in
		  (r, DstIL.OP(DstOp.Neg ty, [r])) :: stms
		end
	    | expand (FieldDef.SUM(fld1, dlf2)) => raise Fail "expandInside: SUM"
	  in
	    List.rev (expand (result, fld))
	  end

  end