System.pas floating point error with Delphi10.3.3 RIO

[jptf59 1]

Hello,

 

Code that worked fine with DELPHI 7 now generates a floating point error in System.Pas provided with the RadStudio 10.3.3 installer.  I use the Win32 platform.

My code is as following  and the problem lies with the round () instruction:

 

  if ( abs(extr.X-centre.X)  < 19) and (abs(extr.Y-centre.Y) < 19) then
     begin
       if (angl >= 45) and (angl < 135) then dl := abs(20/cos(DEC_RAD (90-angl)))
       else
       if  (angl >= 135) and (angl < 225) then dl := abs(20/cos(DEC_RAD (180-angl)))
       else
       if  (angl >= 225) and (angl < 315) then dl := abs(20/cos(DEC_RAD (270-angl)))
       else dl := abs(20/cos(DEC_RAD (-angl)));

       extr.X := org.X + round ( (long - dl) *cos (DEC_RAD(angl)));
       extr.Y := org.Y - round ( (long - dl) * sin (DEC_RAD (angl)));
     end;

The error occurs at the last line with the call to   round (( long - dl)  which calls in turn System._Round that is the intrinsec function compliant with dcc32 here :

{**************************************************}
{                                                  }
{           CodeGear Delphi Runtime Library        }
{                                                      			  }
{ Copyright(c) 1995-2019 Embarcadero Technologies, Inc. 	  }
{              All rights reserved                      			  }
{                                                       			  }
{   Copyright and license exceptions noted in source    		  }
{                                                       			  }
{**************************************************}

unit System; { Predefined constants, types, procedures, }
             { and functions (such as True, Integer, or }
             { Writeln) do not have actual declarations.}
             { Instead they are built into the compiler }
             { and are treated as if they were declared }
             { at the beginning of the System unit.     }
..............
 ----------------------------------------------------- }
{       functions & procedures that need compiler magic }
{ ----------------------------------------------------- }

{$IF defined(CPUX64) and defined(ASSEMBLER)}
function _Round(Val: Extended): Int64;
asm
        .NOFRAME
        CVTSD2SI        RAX, XMM0
end;
{$ELSEIF defined(X86ASMRTL)}
procedure _ROUND;
asm
        { ->    FST(0)  Extended argument       }
        { <-    EDX:EAX Result                  }

        SUB     ESP,12
{$IFDEF IOS} // iOS/Simulator
        CALL    FClearExcept
{$ENDIF IOS}
        FISTP   qword ptr [ESP+4]
        FWAIT
{$IFDEF IOS} // iOS/Simulator
        CALL    FCheckExcept
{$ENDIF IOS}

I get the $C0000090 'floating point invalid operation at 0x00407847' that points to the FWAIT instruction at the end of the _ROUND proc. 

 

What is strange is that the first call to round (long - dl)  does not generate any error  !   I read in the comment here above that the ROUND procedure needs compiler magic.  I do not know what it is and I cannot find it in the compiler options.  What is compiler magic ?

 

And all that works fine with Delphi 7. 

Thank you in advance for your help if you can.

Regards

JP

 

Edited January 17, 2021 by jptf59

[David Heffernan 2345]

This should be simple to resolve. Create a minimal program, including any input, so we can see what combination of rounding mode and input arguments lead to this exception. 

[jptf59 1]

Thank you for your help that was good sense.  I discovered that the issue lies in my input data that was empty at times and not in System.pas !  

Problem solved !

 

Thank you again

 

JP

[Guest]

for that is always recomended "initialize" your vars/objects to avoid randomic and strangers values for consequence!

[David Heffernan 2345]

2 hours ago, jptf59 said:

Thank you for your help that was good sense.  I discovered that the issue lies in my input data that was empty at times and not in System.pas !  

Problem solved !

 

Thank you again

 

JP

Floating point values cannot be empty

[Stano 143]

Um, the basic rule: always check the input arguments!
This is from a wise book