C++ float

[jj2007]

This is from an example how to use C code in assembler (\Masm32\MasmBasic\MB2C\CalcTest.asc):

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extern "C"
int _fltused=1; //get rid of a stupid error message

extern "C"
double _stdcall jjDiv(int x , int y)
{
  try
  {
  float ffx=x*1.001;
  float ffy=y*1.001;
return(ffx/ffy);
  }
  catch (int)
  {
return(0);  //not very useful ;-)
  }
}

Commandline:

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"%ProgramFiles%\Microsoft Visual Studio 10.0\VC\bin\cl.exe" /c /Oty2 /Zl /EHsc /Gs /GS- /FojjCalc.obj /Fa jjCalc.cpp

Question: What I had in mind was a simple return (x/y) - but Olly tells me C++ uses idiv. What is the correct way to force C++ to return a REAL8? My workaround doesn't look very elegant...

[clive]

Something like this should probably suffice:

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float ffx=(float)x*1.001;
float ffy=(float)y*1.001;
return((double)ffx/ffy);

As it traverses left-to-right

[jj2007]

Thanks, Clive - you set me on the right track:

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extern "C"
double _stdcall jjDiv(int x , int y)
{
  try
  {
return((float)x/y);
  }
  catch (int)
  {
return(3.14159);
  }
}


The catch hander is pretty useless, though, as fidiv does not trigger the exception. I would have to set the appropriate FPU mask bit :8)