From: redelm@nospicedham.ev1.net.invalid   
      
   R.Wieser  wrote in part:   
   > Moderator, Frank : I'm not sure if questions about the x87   
   > FPU are permitted here.  If not than please just discard.   
   > If they are than please remove this line. :-)   
   >   
   > Hello all,   
   >   
   > I've just been writing some basic code to parse a simple   
   > float, and realized that I had no idea how to check if the   
   > x87 FPU was empty after I was done - as a simple measure   
   > to check if my code cleaned up correctly.   
      
   You will need FSAVE/FRSTOR (and varients) if you use   
   the x87.  Your first FLD will clobber the stack top,   
   which might be OK only if it is empty.   
      
   >   
   > I've been looking at using the ST bits in the FPU status word, but had to   
   > find that they (unexpectedly) didn't end at zero after I done my thing :   
   >   
   > minimal example:   
   >   
   > fld1    ;Load   
   > fld1   
   >   
   > fstp st(2)   ;Swap ST(0) and ST(1) <-- this is the culprit   
   >   
   > fstp st(0)    ;Discard   
   > fstp st(0)   
   >   
   > At this point all the ST bits are set, indicating a minus one, not zero.   
      
   As another poster has said, I don't think the x87 automagically   
   sets value flags (as x86 does( and needs FXAM.  FSTSW=FF sounds   
   like an empty x87.   
      
   >   
   > My questions at this point are:   
   >   
   > 1) Have I done anything wrong in the above ?  I don't think   
   > so, but "you never know" ....   
   >   
   > 2) How do I, for debugging purposes, check the FPU stack ?   
      
   Dump and examine in main memory.  Like the Hewlett-Packard   
   Reverse Polish Notation calculators it was modelled on,   
   the x87 is meant for crunching together, not picking apart.   
      
   -- Robert   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)