1 files changed, 52 insertions, 0 deletions

diff --git a/src/stable/randomcmwc.cpp b/src/stable/randomcmwc.cpp
new file mode 100644
index 0000000..a4e807e
--- /dev/null
+++ b/src/stable/randomcmwc.cpp
@@ -0,0 +1,52 @@
+/*
+ * Copyright (C) 2007-2012 Xagasoft, All rights reserved.
+ *
+ * This file is part of the libbu++ library and is released under the
+ * terms of the license contained in the file LICENSE.
+ */
+
+#include "bu/randomcmwc.h"
+
+#define PHI 0x9e3779b9
+
+Bu::RandomCmwc::RandomCmwc() :
+        q( 0 ),
+        c( 362436 )
+{
+        q = new uint32_t[4096];
+}
+
+Bu::RandomCmwc::~RandomCmwc()
+{
+        delete[] q;
+}
+
+void Bu::RandomCmwc::seed( int32_t iSeed )
+{
+        int i;
+
+        q[0] = iSeed;
+        q[1] = iSeed + PHI;
+        q[2] = iSeed + PHI + PHI;
+
+        for (i = 3; i < 4096; i++)
+                q[i] = q[i - 3] ^ q[i - 2] ^ PHI ^ i;   
+}
+
+int32_t Bu::RandomCmwc::rand()
+{
+        uint64_t t, a = 18782LL;
+        static uint32_t i = 4095;
+        uint32_t x, r = 0xfffffffe;
+        i = (i + 1) & 4095;
+        t = a * q[i] + c;
+        c = (t >> 32);
+        x = t + c;
+        if( x < c )
+        {
+                x++;
+                c++;
+        }
+        return (q[i] = r - x);
+}
+