From: kusano <kusano@users.noreply.github.com>
Date: Thu, 17 Dec 2015 10:26:38 +0000 (+0900)
Subject: Fix #71152: mt_rand() returns the different values from original mt19937ar.c
X-Git-Tag: php-7.0.5RC1~111
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=6f6bd8ce531636134efd5f669a4e8373fb2e9e51;p=php

Fix #71152: mt_rand() returns the different values from original mt19937ar.c
---

diff --git a/ext/standard/rand.c b/ext/standard/rand.c
index 2dd05e70bb..bc32f24e0b 100644
--- a/ext/standard/rand.c
+++ b/ext/standard/rand.c
@@ -146,7 +146,7 @@ PHPAPI zend_long php_rand(void)
 #define loBits(u)     ((u) & 0x7FFFFFFFU)  /* mask     the highest   bit of u */
 #define mixBits(u, v) (hiBit(u)|loBits(v)) /* move hi bit of u to hi bit of v */
 
-#define twist(m,u,v)  (m ^ (mixBits(u,v)>>1) ^ ((php_uint32)(-(php_int32)(loBit(u))) & 0x9908b0dfU))
+#define twist(m,u,v)  (m ^ (mixBits(u,v)>>1) ^ ((php_uint32)(-(php_int32)(loBit(v))) & 0x9908b0dfU))
 
 /* {{{ php_mt_initialize
  */
diff --git a/ext/standard/tests/math/mt_rand_value.phpt b/ext/standard/tests/math/mt_rand_value.phpt
new file mode 100644
index 0000000000..eeb009e4b4
--- /dev/null
+++ b/ext/standard/tests/math/mt_rand_value.phpt
@@ -0,0 +1,53 @@
+--TEST--
+Test mt_rand() - returns the exact same values as mt19937ar.c
+--FILE--
+<?php
+
+mt_srand(12345678);
+
+for ($i=0; $i<16; $i++) {
+    echo mt_rand().PHP_EOL;
+}
+echo PHP_EOL;
+
+$x = 0;
+for ($i=0; $i<1024; $i++) {
+    $x ^= mt_rand();
+}
+echo $x.PHP_EOL;
+
+/*
+excpect values are obtained from original mt19937ar.c as follows:
+
+int i, x;
+init_genrand(12345678);
+for (i=0; i<16; i++) {
+    printf("%d\n", genrand_int31());
+}
+printf("\n");
+x = 0;
+for (i=0; i<1024; i++) {
+    x ^= genrand_int31();
+}
+printf("%d\n", x);
+*/
+?>
+--EXPECTF--
+527860569
+1711027313
+1280820687
+688176834
+770499160
+412773096
+813703253
+898651287
+52508912
+757323740
+511765911
+274407457
+833082629
+1923803667
+1461450755
+1301698200
+
+1612214270