tools/test/devrandom/stat.8bit

   1 #!/usr/bin/perl
   2
   3 #
   4 # Perform primitive binning into 8-bit bins (take 8 bits of randomness
   5 # at a time) and see if the distribution is flat. The output should be
   6 # checked by eye - are all the numbers roughly the same?
   7 #
   8 # Redirect the output from this to a file - and make a cup of coffee while
   9 # it runs. This program is a CPU Hog!
  10 #
  11 # $FreeBSD: src/tools/test/devrandom/stat.8bit,v 1.4 1999/08/28 00:54:24 peter Exp $
  12 # $DragonFly: src/tools/test/devrandom/stat.8bit,v 1.2 2003/06/17 04:29:11 dillon Exp $
  13 #
  14
  15 for ($i = 0; $i < (1024*32); $i++) {
  16         open(BIN, "/dev/urandom") || die "Cannot open /dev/urandom - $!\n";
  17         $len = sysread(BIN, $a, 256);
  18         close(BIN);
  19         if ($len > 0) {
  20                 for ($j = 0; $j < $len; $j++) {
  21                         $k = unpack("C", substr($a, $j, 1));
  22                         $bin[$k]++;
  23                 }
  24         }
  25 }
  26
  27 for ($i = 0; $i < 256; $i++) {
  28         printf("%.2X ", $bin[$i]);
  29 }
  30 printf "\n";