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    (*
    ===========================================================================
     BBS: Canada Remote Systems
    Date: 05-30-93 (08:25)             Number: 8026
    From: STEVE ROGERS                 Refer#: NONE
      To: PAUL HICKEY                   Recvd: NO
    Subj: HELP PLEASE                    Conf: (1617) L-PASCAL
    ---------------------------------------------------------------------------
    PH> EP> {$M $A,B,C}

    PH> I always set A and B to high and C to 0.  I want to allow the most memory I
    PH>can to program usage within the 640K limit.

      To get the most ram for your prog to use in the 640k set "B" to 0
      and "C" to 655360. Setting "C" to 0 prevents you from accessing any
      heap at all.

      "A" should be set to the amount of stack your program needs. I have a
      unit that I use to help determine this. It was initially released for
      TP4 but I've used with BP7 OK.

    {***********************************************************
      StackUse - A unit to report stack usage information

      by Richard S. Sadowsky
      version 1.0 7/18/88
      released to the public domain

      Inspired by a idea by Kim Kokkonen.

      This unit, when used in a Turbo Pascal 4.0 program, will
      automatically report information about stack usage.  This is very
      useful during program development.  The following information is
      reported about the stack:

      total stack space
      Unused stack space
      Stack spaced used by your program

      The unit's initialization code handles three things, it figures out
      the total stack space, it initializes the unused stack space to a
      known value, and it sets up an ExitProc to automatically report the
      stack usage at termination.  The total stack space is calculated by
      adding 4 to the current stack pointer on entry into the unit.  This
      works because on entry into a unit the only thing on the stack is the
      2 word (4 bytes) far return value.  This is obviously version and
      compiler specific.

      The ExitProc StackReport handles the math of calculating the used and
      unused amount of stack space, and displays this information.  Note
      that the original ExitProc (Sav_ExitProc) is restored immediately on
      entry to StackReport.  This is a good idea in ExitProc in case a
      runtime (or I/O) error occurs in your ExitProc!

      I hope you find this unit as useful as I have!

    ************************************************************)

    {$R-,S-} { we don't need no stinkin range or stack checking! }
    unit StackUse;

    interface

    var
      Sav_ExitProc     : Pointer; { to save the previous ExitProc }
      StartSPtr        : Word;    { holds the total stack size    }

    implementation

    {$F+} { this is an ExitProc so it must be compiled as far }
    procedure StackReport;

    { This procedure may take a second or two to execute, especially }
    { if you have a large stack. The time is spent examining the     }
    { stack looking for our init value ($AA). }

    var
      I                : Word;

    begin
      ExitProc := Sav_ExitProc; { restore original exitProc first }

      I := 0;
      { step through stack from bottom looking for $AA, stop when found }
      while I < SPtr do
        if Mem[SSeg:I] <> $AA then begin
          { found $AA so report the stack usage info }
          WriteLn('total stack space : ',StartSPtr);
          WriteLn('unused stack space: ', I);
          WriteLn('stack space used  : ',StartSPtr - I);
          I := SPtr; { end the loop }
        end
        else
          inc(I); { look in next byte }
    end;
    {$F-}

    begin
      StartSPtr := SPtr + 4; { on entry into a unit, only the FAR return }
                             { address has been pushed on the stack.     }
                             { therefore adding 4 to SP gives us the     }
                             { total stack size. }
      FillChar(Mem[SSeg:0], SPtr - 20, $AA); { init the stack   }
      Sav_ExitProc := ExitProc;              { save exitproc    }
      ExitProc     := @StackReport;          { set our exitproc }
    end.

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