(Frandom): Handle LIMIT >= 40000000.

1 files changed, 17 insertions, 11 deletions

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 ();