From 2bf3e3c4318e4d883329a67a654914a900211c20 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Fri, 1 Jul 2016 16:26:25 +1000
Subject: [PATCH] rand/xorshift: add min/max/discard operations

---
 rand/xorshift.cpp | 27 +++++++++++++++++++++++++++
 rand/xorshift.hpp |  9 ++++++++-
 2 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/rand/xorshift.cpp b/rand/xorshift.cpp
index c7170932..df1f1c42 100644
--- a/rand/xorshift.cpp
+++ b/rand/xorshift.cpp
@@ -74,6 +74,33 @@ xorshift<T>::operator() (void)
 };
 
 
+///////////////////////////////////////////////////////////////////////////////
+template <typename T>
+typename xorshift<T>::result_type
+xorshift<T>::min (void)
+{
+    return 1u;
+}
+
+//-----------------------------------------------------------------------------
+template <typename T>
+typename xorshift<T>::result_type
+xorshift<T>::max (void)
+{
+    return std::numeric_limits<T>::max ();
+}
+
+
+///////////////////////////////////////////////////////////////////////////////
+template <typename T>
+void
+xorshift<T>::discard (unsigned count)
+{
+    while (count--)
+        (*this)();
+}
+
+
 ///////////////////////////////////////////////////////////////////////////////
 template struct util::rand::xorshift<uint32_t>;
 template struct util::rand::xorshift<uint64_t>;
diff --git a/rand/xorshift.hpp b/rand/xorshift.hpp
index 7837c922..ccef2e81 100644
--- a/rand/xorshift.hpp
+++ b/rand/xorshift.hpp
@@ -26,9 +26,16 @@ namespace util { namespace rand {
     template <typename T>
     struct xorshift {
     public:
+        using result_type = T;
+
         xorshift (T seed);
 
-        T operator() (void);
+        result_type operator() (void);
+
+        static result_type min (void);
+        static result_type max (void);
+
+        void discard (unsigned);
 
     private:
         T m_state;