From: janis_papanagnou+ng@hotmail.com   
      
   On 2025-12-22 19:45, Michael S wrote:   
   > [...] LFSR is a reasonably good PRNG for a single bit, but   
   > not when you want to generate a group of 31 pseudo-random bits. In   
   > order to get 31 new bits, without predictable repetitions from the   
   > previous value, you would have to do 31 steps. That's slow! The process   
   > can be accelerate by generation of several bits at time via look up   
   > tables, but in order to get decent speed the table has to be rater big   
   > and using big tables in standard library is bad sportsmanship.   
      
   Yes. But mind that the speed is also depending on what quality you   
   need. For example; I used the PN-generator to create bit-sequences   
   (as you also suggest). For another application both, PN-LFSR and   
   LCG (that you mention below), were inacceptable; we used a cipher   
   to create the random data. (If you compare the speed of creating   
   the cipher to a bit-shift-register the latter looks really fast.)   
      
   >   
   > It seems that overwhelming majority C RTLs use Linear Congruential   
   > Generators, probably because for Stanadard library compactness of both   
   > code and data is considered more important than very high speed (not   
   > that on modern HW LCGs are slow) or superior random properties of   
   > Mersenne Twisters.   
      
   For "standard applications" I always used the simple LCGs; simple   
   and fast. Or whatever the tools or library provided; which were   
   mostly anyway LCGs.   
      
   Janis   
      
   > [...]   
      
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