From: Ben Pfaff <blp@gnu.org>
Date: Tue, 3 Feb 2004 07:47:46 +0000 (+0000)
Subject: (rng_get_double) Fix always-returning-zero bug in my preferred way,
X-Git-Tag: v0.4.0~382
X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=957761c7598cdbd1140e08962cd6999c6ce9437f;p=pspp-builds.git

(rng_get_double) Fix always-returning-zero bug in my preferred way,
and at the same time make sure rounding doesn't bite us.
---

diff --git a/src/ChangeLog b/src/ChangeLog
index aa539583..61713e2a 100644
--- a/src/ChangeLog
+++ b/src/ChangeLog
@@ -1,3 +1,9 @@
+Mon Jan 19 14:08:09 2004  Ben Pfaff  <blp@gnu.org> 
+
+	* random.c (rng_get_double): Fix always-returning-zero bug in my
+	preferred way, and at the same time make sure rounding doesn't
+	bite us.
+
 Thu Jan  1 23:16:41 2004  Ben Pfaff  <blp@gnu.org>
 
 	* html.c: (change_attributes) Dead code, removed.
diff --git a/src/random.c b/src/random.c
index 163986cc..20a70fae 100644
--- a/src/random.c
+++ b/src/random.c
@@ -159,10 +159,16 @@ rng_get_unsigned (struct rng *rng)
 double
 rng_get_double (struct rng *rng) 
 {
-  unsigned long value;
-
-  rng_get_bytes (rng, &value, sizeof value);
-  return value / (double) ULONG_MAX;
+  for (;;) 
+    {
+      unsigned long ulng;
+      double dbl;
+  
+      rng_get_bytes (rng, &ulng, sizeof ulng);
+      dbl = ulng / (ULONG_MAX + 1.0);
+      if (dbl >= 0 && dbl < 1)
+        return dbl;
+    }
 }
 
 /* Returns a random number from the distribution with mean 0 and