From: Richard M. Stallman <rms@gnu.org>
Date: Sat, 30 Jul 1994 21:17:41 +0000 (+0000)
Subject: (Frandom): Handle LIMIT >= 40000000.
X-Git-Tag: emacs-19.34~7465
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=d1ab4ede1f214fa520b8f64d17ab3c36f1daf858;p=emacs.git

(Frandom): Handle LIMIT >= 40000000.
---

diff --git a/src/fns.c b/src/fns.c
index c91710b7c10..b65f3f203f7 100644
--- a/src/fns.c
+++ b/src/fns.c
@@ -64,17 +64,23 @@ With argument t, set the random number seed from the current time and pid.")
     srandom (getpid () + time (0));
   if (XTYPE (limit) == Lisp_Int && XINT (limit) > 0)
     {
-      /* Try to take our random number from the higher bits of VAL,
-	 not the lower, since (says Gentzel) the low bits of `random'
-	 are less random than the higher ones.  We do this by using the
-	 quotient rather than the remainder.  At the high end of the RNG
-	 it's possible to get a quotient larger than limit; discarding
-	 these values eliminates the bias that would otherwise appear
-	 when using a large limit.  */
-      denominator = (unsigned long)0x40000000 / XFASTINT (limit);
-      do
-	val = (random () & 0x3fffffff) / denominator;
-      while (val >= limit);
+      if (XINT (limit) >= 0x40000000)
+	/* This case may occur on 64-bit machines.  */
+	val = random () % XINT (limit);
+      else
+	{
+	  /* Try to take our random number from the higher bits of VAL,
+	     not the lower, since (says Gentzel) the low bits of `random'
+	     are less random than the higher ones.  We do this by using the
+	     quotient rather than the remainder.  At the high end of the RNG
+	     it's possible to get a quotient larger than limit; discarding
+	     these values eliminates the bias that would otherwise appear
+	     when using a large limit.  */
+	  denominator = (unsigned long)0x40000000 / XFASTINT (limit);
+	  do
+	    val = (random () & 0x3fffffff) / denominator;
+	  while (val >= limit);
+	}
     }
   else
     val = random ();