Merge in an ugly pile of rand* functions from glibc. :(

1 files changed, 48 insertions, 0 deletions

diff --git a/libc/stdlib/rand_r.c b/libc/stdlib/rand_r.c
new file mode 100644
index 000000000..610044083
--- /dev/null
+++ b/libc/stdlib/rand_r.c
@@ -0,0 +1,48 @@
+/* Reentrant random function frm POSIX.1c.
+   Copyright (C) 1996, 1999 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@cygnus.com <mailto:drepper@cygnus.com>>, 1996.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
+   02111-1307 USA.  */
+
+#include <stdlib.h>
+
+
+/* This algorithm is mentioned in the ISO C standard, here extended
+   for 32 bits.  */
+int rand_r (unsigned int *seed)
+{
+    unsigned int next = *seed;
+    int result;
+
+    next *= 1103515245;
+    next += 12345;
+    result = (unsigned int) (next / 65536) % 2048;
+
+    next *= 1103515245;
+    next += 12345;
+    result <<= 10;
+    result ^= (unsigned int) (next / 65536) % 1024;
+
+    next *= 1103515245;
+    next += 12345;
+    result <<= 10;
+    result ^= (unsigned int) (next / 65536) % 1024;
+
+    *seed = next;
+
+    return result;
+}