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???
09/12/07 09:03
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 		 #144437 - tell us what is the application
Responding to: ???'s previous message
Radouane Essellak said:
So it suffices to call xtea(&key) to use the cipher as prng.

Yes; however, it's upon you to seed (initialize) it properly.

Radouane Essellak said:
If I want a float range [0.0,1.0] numbers, what should I do ?
Should I divide by 2^64-1 ?


Formally, yes; although depending on the particular format "float" uses, truncation might occur, which might influence the uniformity. But how are you going to accomplish it? There is nothing like 64-bit arithmetics implemented in SDCC. And, it's most probably not necessary, either.

You might perhaps give us more details on your application, so that we can give you a few more hints. Meantime, you might want to read some of the FAQs present on this site, maybe starting with http://www.8052.com/faqs.phtml?FAQ=119919 .

JW

List of 25 messages in thread
TopicAuthorDate
HOWTO generate a uniformly-distributed random nu            01/01/70 00:00      
   how much code/data/idata/xdata space can you...            01/01/70 00:00      
      I can wait till evening            01/01/70 00:00      
      LFSR            01/01/70 00:00      
         OK but            01/01/70 00:00      
            there is no such thing            01/01/70 00:00      
               event triggered Timer reading            01/01/70 00:00      
                  no, well            01/01/70 00:00      
            LFSRs generally suffer from the "bad seed" problem            01/01/70 00:00      
               Maximal-Length LFSR?            01/01/70 00:00      
                  uniformity is not the only requirement on a pRNG..            01/01/70 00:00      
   most rng's            01/01/70 00:00      
      hummm            01/01/70 00:00      
         pseudorandom is NOT random            01/01/70 00:00      
            A Dilbert            01/01/70 00:00      
   Easy way to have it ???            01/01/70 00:00      
      block cipher, in chaining mode...            01/01/70 00:00      
      on uniformity of pseudo- or real-random            01/01/70 00:00      
         what's xtea prng RANGE ?            01/01/70 00:00      
            its not a dedicated pRNG algorithm....            01/01/70 00:00      
               random float ??            01/01/70 00:00      
                  tell us what is the application            01/01/70 00:00      
                     The application is...            01/01/70 00:00      
                        take any 32 bits...            01/01/70 00:00      
                           OK            01/01/70 00:00      

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