Question

I am trying to compile libsoxr (it is derived from libsox library by Audacity team) library. I can compile osx 32, osx 64 and win32. They use inline asm and Windows x64 platform doesn’t support inline asm. Problematic code piece is this:

#if HAVE_FENV_H
  #include <fenv.h>
#elif defined _MSC_VER
  #define FE_INVALID    1
  #define FE_DIVBYZERO  4
  #define FE_OVERFLOW   8
  #define FE_UNDERFLOW  16
  #define FE_INEXACT    32
  #define FE_ALL_EXCEPT (FE_INEXACT|FE_DIVBYZERO|FE_UNDERFLOW|FE_OVERFLOW|FE_INVALID)
  static __inline int fetestexcept(int excepts)
  {
    short status_word;
    __asm fnstsw status_word
    return status_word & excepts & FE_ALL_EXCEPT;
  }

  static __inline int feclearexcept(int excepts)
  {
    int16_t status[14];
    __asm fnstenv status
    status[2] &= ~(excepts & FE_ALL_EXCEPT);
    __asm fldenv status
    return 0;
  }
#endif

I don’t know what fnstenv and fldenv do. May somebody guide me for making compatible with x64?

Answer 1

Assuming that you are compiling with the Microsoft compiler then you can use RTL functions instead of inline assembly.

To test for particular floating point status flags call _statusfp. To clear floating point status flags call _clearfp.

In order to use _statusfp you’ll need to translate from the raw 8087 flags, to the abstract flags used by _statusfp.

Update

The code in the question is an implementation of a small part of fenv.h which is part of C99. It’s needed for the MS compiler since it only implements C89. In my view you would be much better off using a real C99 compiler. That would come with an implementation of fenv.h.