[fpc-devel] MM_MaskInvalidOp in mxcsr

Markus Beth markus.beth at zkrd.de
Fri Sep 3 12:05:23 CEST 2010

Is there a reason why MM_MaskInvalidOp is not set in mxcsr in 

I have a 3rd party application that depends on InvalidOp to be masked 
out. I want to extend this application with a FPC library. But the 
initialization code of the library (SysInitFPU) unmasks the InvalidOp 

I now call "SetSSECSR(GetSSECSR or $0080);" in the initialization 
section of my main unit to mask out the InvalidOp exception again.
But I wonder if this could break something (in rtl or internal FPC 
functions). I fear it is unmasked on purpose in SysInitFPU because 
according to the Intel documentation (Intel Software Developers Manual 
2A) "The default MXCSR value at reset is 1F80H."

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