[RC5] Use of FPU on Intel 486 and P5 processors

gindrup at okway.okstate.edu gindrup at okway.okstate.edu
Wed Jan 14 09:45:37 EST 1998


     I replied indicating that every FPU instruction used in the snippets 
     of code you listed were non-pairable FPU instructions.  Try 
replacing 
     FSCALE with FMUL (by 2^-(rotate)) and FADD 1.0e0.  Both FMUL and 
FADD 
     are pairable on the P5.  They also have useful concurrent execution 
     properties on the '486.  Alternatively, it may be faster to just 
     directly manipulate the exponent to force the normalization hardware 
     to perform the rotate at the end of the next operation.
            -- Eric Gindrup ! gindrup at okway.okstate.edu


______________________________ Reply Separator 
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Subject: Re: [RC5] Use of FPU on Intel 486 and P5 processors 
Author:  <rc5 at llamas.net > at SMTP
Date:    1/14/98 3:38 PM


     [snip]
I provided code which didn't do it and noone has yet pointed out what 
was done incorrectly.
     
I am very interested in getting this working.
     
Bruce Ford
     
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