{

                          Module 25


                      Program Parameters





 Pascal contains provision for the exchange of information  between
 a program and its run time environment by means of program parame-
 ters.  In  practice  most  implementations  (including  the  model
 implementation) provide only a skeleton frame work which is suffi-
 cient to map actual data files onto their respective program  file
 variables.   The  P-machine  contains a special P-code to enable a
 mapping  between  a  named  program  parameter  variable   and   a
 corresponding   external entity to be established.  No restriction
 on the parameter type is enforced but the P-code operates  on  the
 assumption that the entities involved are data files.

 The following procedures are invoked  to  generate  the  parameter
 mapping  code.  Each formal parameter is denoted by its associated
 variable  name  and  an  ordinal  position  number  which   allows
 actual/formal  correspondence  to  be  established.   No  means of
 returning information to the external environment is provided  and
 procedure ReturnProgParameter is consequently a dummy.


                                                                     }

program ProgramParams;

#include "globals.x"
#include "codeutils.pf"

procedure OpenProgParameterList;
visible;

  begin
    if CodeIsToBeGenerated then ProgPmCount := 0
  end { openprogparameterlist };

procedure AcceptProgParameter (ParamId : IdEntry);
visible;

  var Size: 0..AlfaSize;
      i: AlfaIndex;

  begin
    if CodeIsToBeGenerated
    then
      with ParamId^ do
        begin
          with VarAddress do
            AccessWord(BlockLevel, WordOffset, LoadRefOp);
          {Pcode3(MapProgParam);				}
          with Name do
            begin
              Size := 0;
              for i := 1 to AlfaSize do
                if Head[i] <> ' ' then Size := Size + 1;
              { check tail if necessary }
              {CodeByte(Size + 1);
              ProgPmCount := ProgPmCount + 1;
              CodeByte(ProgPmCount);
              for i := 1 to Size do CodeByte(ord(Head[i]));	}
              { emit tail if necessary }
            end
        end
  end { acceptprogparameter };

procedure ReturnProgParameter (ParamId : IdEntry);
visible;

  begin  end;

procedure CloseProgParameterList;
visible;

  begin  end;

begin
{ end of module }
end.