On Thursday, 1 October 2015 at 11:40:28 UTC, Marco Leise wrote:
Note that the FP control word is per thread and any external code you call or even buggy interrupt handlers could change or reset it to defaults. Known cases include a faulty printer driver and Delphi's runtime, which enables FP exceptions to throw exceptions on division by 0. Just saying this so if it ever happens you have it in the back of your mind. Against interrupt handlers you probably cannot protect, but when calling other people's code it would be best not depend on what the FP control word is set to on return. `FloatingPointControl` is nice here, because you can temporarily set the rounding mode directly for a block of FP instructions where no external libraries are involved.
I have a RAII struct to save/restore the FP control word. It also handle the SSE control word which unfortunately exist. https://github.com/p0nce/dplug/blob/master/plugin/dplug/plugin/fpcontrol.d
