The Wiert Corner - irregular stream of stuff: jpluimers

The question datetime – Delphi Now() function returns a wrong value – Stack Overflow is similar to my article Delphi – Michael Justin had strange floating point results when his 8087 FPU Control Word got hosed.

Good that stackoverflow user Anton Zhuchkov found out the cause himself: his answer indicates the Precision Control (and rounding) part of the FPU state got hosed by wrongly initializing the Direct3D device.

I edited his answer with some extra links to documentation.

Finally I’ve found the solution. I needed to specify the D3DCREATE_FPU_PRESERVE flag when creating a D3D device by D3D.CreateDevice.

Otherwise, without that flag, all floating point operations are performed with single precision. As the TDateTime is a simple Double, and Now() functions is consist of simple addition of date value to time value, it all get messed up by DirectX “smart” override.

Problem solved. It was a tricky one indeed. :)

–jeroen

via: datetime – Delphi Now() function returns a wrong value – Stack Overflow.