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

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   Message 3,800 of 4,675   
   Terje Mathisen to James Harris   
   Re: Fast conversion to a boolean of 0 or   
   07 Mar 19 07:35:50   
   
   From: terje.mathisen@nospicedham.tmsw.no   
      
   On Wednesday, March 6, 2019 at 2:47:41 PM UTC-5, James Harris wrote:   
   > A small programming challenge if you are interested, just for fun.   
      
   What happens if you do:   
      
      neg eax   
      mov eax,0   
      adc eax,eax   
      
   This does not use any extra regs, and the NEG and the MOV should still   
   run in the same cycle even if they both use EAX as the target. This is   
   because the MOV form is known to not depend on the previous value in   
   EAX, so it can be started even before the NEG.   
      
   Terje   
      
      
   --   
   -    
   "almost all programming can be viewed as an exercise in caching"   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)   

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