[RC5] A whole bunch of things

gindrup at okway.okstate.edu gindrup at okway.okstate.edu
Thu Nov 20 19:36:04 EST 1997


     I posted a method for doing the all important rotates in FP.  The 
     modulo additions are trivial.  The only real trouble you'd have is on 
     architectures with only one "full size" FP register or some (popular) 
     idiotic architecture that uses a FPU *stack*.  Then you'd have to 
     continually be loading and reloading "A" and "B" into the FPU 
     register.
     
     On (popular) idiotic hardware, I'd expect this to be no better than 
     the rotateless clients.  However, this has the advantage of being 
     parallelizable with the normal client on the same hardware.  Some 
     other platforms also allow parallelized FP execution.
            -- Eric Gindrup ! gindrup at Okway.okstate.edu


______________________________ Reply Separator _________________________________
Subject: [RC5] A whole bunch of things 
Author:  <rc5 at llamas.net > at SMTP
Date:    1997/11/20 04:02


[snip]
1) Would it be possible to write a client that does the computation using 
floating point numbers and therefore run off the FPU. Off hand I can't 
think of any reason why you couldn't, I was just wondering what kind of 
performance you would get, especially on chips like the PPC 604e that are 
designed for extreme floating point operation. I'm thinking that it would 
still probably be slower, but (at 4 in the morning and now listening to the 
Beegees) I can't think of any kind of legitimate comparison between the CPU 
and FPU (running LibMoto) in real world work.
     [snip]


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