Review Board 2.0.15


BASE: Fix genrand to generate both 0s and 1s when max equals one.

Review Request #157 - Created Aug. 13, 2010 and submitted

Information
Ali Saidi
gem5
Reviewers
Default 
BASE: Fix genrand to generate both 0s and 1s when max equals one.
previously was only generating 0s.

   

  


 


 

  

  









  
 


  

 
















 



 

  


 


  



   

   
Steve Reinhardt

   
Posted  (Aug. 13, 2010, 8:57 a.m.)


  


  


  

   
Is this right?  Seems like genrand(1) and genrand(2) will now do the same thing.  Should we be calling ceilLog2(max+1) instead?




  

   

   
    
    

   
  1. 
    
    
     
    
      
     
    
     
    You're right Steve, it still fails on powers of two. I tested from 0 to 10 and it was correct with ceilLog2(max) + 1, so I'll go with that.
    
    
    
   
    2. 


   
  2. 
    
    
     
    
      
     
    
     
    I'm happy to review an updated diff if you like.
    
    
    
   
    3. 


   
  3. 
    
    
     
    
      
     
    
     
    It just turned into:
    if (max == 0)
        return 0;
    int log = ceilLog2(max) + 1;

I tested it for max = 0 to max = 10 and it produced the appropriate results each time. The previous change would fail on powers of two.
    
    
    
   
    4.