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   comp.lang.asm.x86      Ahh, the lost art of x86 assembly      4,675 messages   

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   Message 3,374 of 4,675   
   wolfgang kern to Rod Pemberton   
   Re: Reciprocal MUL LUT   
   26 Apr 18 16:11:35   
   
   From: nowhere@never.at   
      
   Rod Pemberton asked:   
      
   >> I try to shorten my current 512 bit 1/primes LUT   
      
   > What is the largest prime currently in your LUT?  I.e., is this LUT   
   > very small, such as primes less than 100, or, is this LUT huge, such as   
   > having millions of primes?   
      
   work is still in progress ...   
   for now I test with only 16bit primes (largest: 0xfff1, count: 0x198e)   
      
   >> values for higher primes will really need 512 bits or more   
      
   > So, your LUT has 1/prime decimal fractions, converted to binary, which   
   > have periods that reach and exceed 512 bits?   
      
   Uint, Not decimal!  dec 1/P periods are quite different to bin 1/P.   
      
   my first idea was to just use equal scaled 64 byte entries, but this soon   
   may become a heavy bloated story. So I check yet if different scaled periods   
   can save a lot on size w/o loosing too much speed.   
      
   > What is the smallest prime in your LUT which has a period of 512 bits?   
      
   haven't checked it yet, I have to write a period detector first.   
   __   
   wolfgang   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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