COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	procedure DUPLICATE (D1 , D2 : STKINX D2TYP : OPNDTYPE )
C00005 ENDMK
C⊗;
procedure DUPLICATE (D1 , D2 : STKINX; D2TYP : OPNDTYPE );
(* Basic procedure used by UDUP and USWP to duplicate a DATUM from D2 to D1*)

    begin
    STK[D1].CODESTART := STK[D2].CODESTART; 
    if STK[D1].CODESTART <> nil then ASSERTFAIL ('CODST_NOTNIL');
    STK[D1].DTYPE := STK[D2].DTYPE ;
    if D2TYP = TYPB then 
	begin
        STK[D1].BREPRES := STK[D2].BREPRES;
        STK[D1].BTRUELIST := STK[D2].BTRUELIST;
	STK[D1].BFALSELIST := STK[D2].BFALSELIST;
	STK[D1].BFALLTHRUSKIPLOC := STK[D2].BFALLTHRUSKIPLOC;
	STK[D1].BJUMPON := STK[D2].BJUMPON;
	end 
    else if D2TYP =TYPS then
	begin
	STK[D1].SCNST := STK[D2].SCNST ;
	STK[D1].SETPARTS := STK[D2].SETPARTS;
	end
    else if D2TYP = TYPR then
	STK[D1].RCNST := STK[D2].RCNST;
    STK[D1].ADDRORVAL := STK[D2].ADDRORVAL;
    end (*DUPLICATE*);


UDUP :
    begin
    if TOP < BOT then ERROR(WDUP_ON_EMPTY_STACK);
    if TYP <> STK[TOP].DTYPE THEN ERROR (WINSTR_TYPE_NOT_DATUM_TYPE);
        if STK[TOP].BTRUELIST.FIRST <> nil then ASSERTFAIL ('TLIST_NOTNIL');
        if STK[TOP].BFALSELIST.FIRST <> nil then ASSERTFAIL ('FLIST_NOTNIL');
        if STK[TOP].BFALLTHRUSKIPLOC <> nil then ASSERTFAIL ('FALLT_NOTNIL');
    PUSHTOP;  ZERO_DATUM(TOP);
    DUPLICATE(TOP, TOP-1, TYP);
    end(*UDUP*);

USWP :
    begin
    if TOP <= BOT then ERROR(WSWP_NOT_2);
    if ((STK[TOP].DTYPE <> TYP) or (STK[TOP-1].DTYPE <> TYP2)) then
	ERROR(USWP_TYP_ERROR);
    DUPLICATE(TMPD1, TOP, TYP);
    DUPLICATE(TOP, TOP-1), TYPO2);
    DUPLICATE(TOP-1, TMPD1, TYP);
    end(*USWP*);

    WSWP_NOT_2,

	WSWP_NOT_2 :
	    begin
	    WRITELN(OUTPUT,'SWP with less than 2 DATUMs on STACK')
	    end;