Pascal Example in Programmer's Guide Won't Compile

• Microsoft Mouse Driver for MS-DOS, versions 6.x, 7.x, 8.x, and 9.0

SUMMARY

The "Making Calls from Borland Turbo Pascal Programs" sample in Appendix E of the "Microsoft Mouse Programmer's Reference" does not compile with Turbo Pascal versions 5.0 and 6.0.

MORE INFORMATION

The CpuReg data structure needs to be defined as "Registers" variables. The semicolons need to be removed from the END lines that immediately precede ELSE. Finally, finding the segment and offset of the pointer of the address of the user array or subroutine (functions 9,12,20,22,23,and 24) needs to be done outside of this procedure. Passing the first element of the array or the start point of the subroutine into the procedure, then calling the "ofs" and "seg" functions in the procedure doesn't seem to work. This is due to how the variables get dereferenced when passed into a procedure.

The following example compiles in both Turbo Pascal version 6.0 and Quick Pascal version 1.00:

Procedure Mouse (Var m1, m2, m3, m4, m5 : integer );

Var

   CpuReg: Registers;

   if m1 >= 0 then
      begin
     CpuReg.AX := m1;        { Load Parameters       }
     CpuReg.BX := m2;        { into appropriate      }
     CpuReg.CX := m3;        { registers             }

     if (m1 = 9) or (m1 = 12) or (m1 = 20)
        or (m1 = 22) or (m1 = 23) or (m1 = 24) then
        begin
          CpuReg.DX  :=  m4;    {m4 = offset,         }
          CpuReg.ES  :=  m5;    { and m5 = segment    }
        end                       { of the user array }
                         { or subroutine     }

      else
      if  m1 = 16  then
       begin
         CpuReg.CX  := m2;           {Left  x coordinate }
         CpuReg.DX  := m3;           {Upper y coordinate }
         CpuReg.SI  := m4;           {Right x coordinate }
         CpuReg.DI  := m5;           {Lower y coordinate }
       end
     else
         CpuReg.DX  := m4;

     Intr($33, CpuReg);              {Call mouse driver  }
                            { at Interrupt 33H  }

     m1 := CpuReg.AX;                {Return values back }
     m2 := CpuReg.BX;                { to parameters     }
     m3 := CpuReg.CX;
     m4 := CpuReg.DX;

     if (m1 = 20) then               {special returns    }
        m2 := CpuReg.ES              { from subroutines  }
   end;

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