1 files changed, 93 insertions, 0 deletions
diff --git a/dist/Math-BigInt/t/mbi_rand.t b/dist/Math-BigInt/t/mbi_rand.t
new file mode 100644
index 0000000000..e2bf6637de
--- /dev/null
+++ b/dist/Math-BigInt/t/mbi_rand.t
@@ -0,0 +1,93 @@
+#!/usr/bin/perl -w
+
+use Test::More;
+use strict;
+
+my $count;
+  
+BEGIN
+  {
+  $| = 1;
+  if ($^O eq 'os390') { print "1..0\n"; exit(0) } # test takes too long there
+  unshift @INC, '../lib'; # for running manually
+  my $location = $0; $location =~ s/mbi_rand.t//;
+  unshift @INC, $location; # to locate the testing files
+  chdir 't' if -d 't';
+  $count = 128;
+  plan tests => $count*4;
+  }
+
+use Math::BigInt;
+my $c = 'Math::BigInt';
+
+my $length = 128;
+
+# If you get a failure here, please re-run the test with the printed seed
+# value as input "perl t/mbi_rand.t seed" and send me the output
+
+my $seed = ($#ARGV == 0) ? $ARGV[0] : int(rand(1165537));
+print "# seed: $seed\n"; srand($seed);
+
+print "# lib: ", Math::BigInt->config()->{lib},"\n";
+if (Math::BigInt->config()->{lib} =~ /::Calc/)
+  {
+  print "# base len: ", scalar Math::BigInt::Calc->_base_len(),"\n";
+  }
+
+my ($A,$B,$As,$Bs,$ADB,$AMB,$la,$lb);
+my $two = Math::BigInt->new(2);
+for (my $i = 0; $i < $count; $i++)
+  {
+  # length of A and B
+  $la = int(rand($length)+1); $lb = int(rand($length)+1);
+  $As = ''; $Bs = '';
+
+  # we create the numbers from "patterns", e.g. get a random number and a
+  # random count and string them together. This means things like
+  # "100000999999999999911122222222" are much more likely. If we just strung
+  # together digits, we would end up with "1272398823211223" etc. It also means
+  # that we get more frequently equal numbers or other special cases.
+  while (length($As) < $la) { $As .= int(rand(100)) x int(rand(16)); }
+  while (length($Bs) < $lb) { $Bs .= int(rand(100)) x int(rand(16)); }
+
+  $As =~ s/^0+//; $Bs =~ s/^0+//; 
+  $As = $As || '0'; $Bs = $Bs || '0';
+#  print "# As $As\n# Bs $Bs\n";
+  $A = $c->new($As); $B = $c->new($Bs);
+  print "# A $A\n# B $B\n";
+  if ($A->is_zero() || $B->is_zero())
+    {
+    for (1..4) { is (1,1, 'skipped this test'); } next;
+    }
+
+  # check that int(A/B)*B + A % B == A holds for all inputs
+
+  # $X = ($A/$B)*$B + 2 * ($A % $B) - ($A % $B);
+
+  ($ADB,$AMB) = $A->copy()->bdiv($B);
+  print "# ($A / $B, $A % $B ) = $ADB $AMB\n";
+
+  print "# seed $seed, ". join(' ',Math::BigInt::Calc->_base_len()),"\n".
+        "# tried $ADB * $B + $two*$AMB - $AMB\n"
+   unless is ($ADB*$B+$two*$AMB-$AMB,$As, "ADB * B + 2 * AMB - AMB == A");
+  if (is ($ADB*$B/$B,$ADB, "ADB * B / B == ADB"))
+    {
+    print "# seed: $seed, \$ADB * \$B / \$B = ", $ADB * $B / $B, " != $ADB (\$B=$B)\n";
+    if (Math::BigInt->config()->{lib} =~ /::Calc/)
+      {
+      print "# ADB->[-1]: ", $ADB->{value}->[-1], " B->[-1]: ", $B->{value}->[-1],"\n";
+      }
+    }
+  # swap 'em and try this, too
+  # $X = ($B/$A)*$A + $B % $A;
+  ($ADB,$AMB) = $B->copy()->bdiv($A);
+  # print "check: $ADB $AMB";
+  print "# seed $seed, ". join(' ',Math::BigInt::Calc->_base_len()),"\n".
+        "# tried $ADB * $A + $two*$AMB - $AMB\n"
+   unless is ($ADB*$A+$two*$AMB-$AMB,$Bs, "ADB * A + 2 * AMB - AMB == B");
+  print "# +$two * $AMB = ",$ADB * $A + $two * $AMB,"\n";
+  print "# -$AMB = ",$ADB * $A + $two * $AMB - $AMB,"\n";
+  print "# seed $seed, \$ADB * \$A / \$A = ", $ADB * $A / $A, " != $ADB (\$A=$A)\n"
+   unless is ($ADB*$A/$A,$ADB, "ADB * A/A == ADB");
+  }
+