freepascal.compiler/docs/heapex/setinfo.pp

Program heapex;

{ Program used to demonstrate the usage of heaptrc unit }

Uses heaptrc;

Var P1 : ^Longint;
    P2 : Pointer;
    I : longint;
    Marker : Longint; 
 
Procedure SetMarker (P : pointer);

Type PLongint = ^Longint;

begin
  PLongint(P)^:=Marker;
end; 
    
Procedure  Part1;
        
begin
  // Blocks allocated here are marked with $FFAAFFAA = -5570646
  Marker := $FFAAFFAA;
  New(P1);
  New(P1);
  Dispose(P1);
  For I:=1 to 10 do
    begin
    GetMem (P2,128);
    If (I mod 2) = 0 Then FreeMem(P2,128);
    end;  
  GetMem(P2,128);
end;

Procedure  Part2;
        
begin
  // Blocks allocated here are marked with $FAFAFAFA = -84215046
  Marker := $FAFAFAFA;
  New(P1);
  New(P1);
  Dispose(P1);
  For I:=1 to 10 do
    begin
    GetMem (P2,128);
    If (I mod 2) = 0 Then FreeMem(P2,128);
    end;  
  GetMem(P2,128);
end;

begin
 SetExtraInfo(SizeOf(Marker),@SetMarker);
 Writeln ('Part 1');
 part1;
 Writeln('Part 2');
 part2;
end.