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[Followups have been trimmed to comp.os.msdos.programmer]

Fred Charles Merkel (merkel@dolphin.upenn.edu) wrote:
> I just received a huge chunk of data in "Microsoft Binary Format".  The
> data are in four byte words, but they don't seem to correspond to normal
> floats or ints.  
>
> Does anyone know what MBF is or can anyone give me some pointers to finding
> out more?

Microsoft's C compilers include runtime library functions to convert
between MBF and IEEE floating-point formats.  If you have four-byte
MBF numbers, the function you need is _fmsbintoieee().  For eight-byte
double-precision MBF numbers, you'd use _dmsbintoieee().

Borland's compilers don't include these functions in their runtime
library, but C source to implement these functions can be obtained
from:

ftp://ftp.borland.com/pub/techinfo/techdocs/language/c++/bcpp/msbin.zip

Note, however, that there's a slight bug in Borland's implementation
of _fmsbintoieee().

The lines:

   /* any msbin w/ exponent of zero = zero */
   if (msbin[3] == 0) return 0;

...should be changed to:

   /* any msbin w/ exponent of zero = zero, and any msbin 
      w/ exponent < 2 is too small to represent in IEEE format */
   if (msbin[3] < 2) return 0;
   
...otherwise very small numbers will produce erroneous results.

---
Glen Blankenship
obother@netcom.com