[Click] random bit errors element

[Eddie Kohler]

OK, cool; do look at the code in CVS and see whether it agrees.  It is wise to 
right-shift the result of random() because in many implementations its 
low-order bits are less random than its higher-order bits.

E


Alastair McKinley wrote:
> On Feb 27 2006, Eddie Kohler wrote:
> 
>> Hi Alastair,
>>
>> Thanks for the patch! You missed one important fix, around line 168, 
>> which would need changes to produce a random number with 28 bits of 
>> randomness. There are a few other places too. I've checked in a fixed 
>> (I hope) version that seems to work. Thanks again!
>>
>> Eddie
>>
>>
> Hi Eddie,
> 
> Thanks for the email.  I think I just sorted it out myself, at least it
> was working pretty much as I expected (I was working on a proper test
> this afternoon!). I was also wondering about something, why do you bit
> shift the values from random() eg.
> 
> int v = (random() >> 3) & 0xFFFFFFF;
> 
> and
> 
> unsigned char errors = bit_flip_array[ ((random() >> 5) % n) + idx ];
> 
> I didnt quite figure that out, but anyway!
> 
> Thanks again,
> 
> Alastair