From cfe1185621c42a08c9a9dcc050f0d784054c5722 Mon Sep 17 00:00:00 2001
From: Danny Robson <danny@nerdcruft.net>
Date: Fri, 22 Dec 2017 12:33:29 +1100
Subject: [PATCH] maths: move log2 into header for constexpr

---
 maths.cpp | 21 ---------------------
 maths.hpp | 11 +++++++++--
 2 files changed, 9 insertions(+), 23 deletions(-)

diff --git a/maths.cpp b/maths.cpp
index ec39ea19..cc3493e3 100644
--- a/maths.cpp
+++ b/maths.cpp
@@ -31,27 +31,6 @@ template uint32_t util::log2up (uint32_t);
 template uint64_t util::log2up (uint64_t);
 
 
-///////////////////////////////////////////////////////////////////////////////
-template <typename T>
-T
-util::log2 (T v)
-{
-    static_assert (std::is_integral<T>::value,
-                   "log2 is only implemented for integers");
-
-    T l = 0;
-    while (v >>= 1)
-        ++l;
-
-    return l;
-}
-
-template uint8_t  util::log2 (uint8_t);
-template uint16_t util::log2 (uint16_t);
-template uint32_t util::log2 (uint32_t);
-template uint64_t util::log2 (uint64_t);
-
-
 ///////////////////////////////////////////////////////////////////////////////
 template const float  util::PI<float>;
 template const double util::PI<double>;
diff --git a/maths.hpp b/maths.hpp
index d6aa3f19..24ad136b 100644
--- a/maths.hpp
+++ b/maths.hpp
@@ -242,8 +242,15 @@ namespace util {
     //-----------------------------------------------------------------------------
     // Logarithms
     template <typename T>
-    T
-    log2  (T val);
+    constexpr
+    std::enable_if_t<std::is_integral_v<T>, T>
+    log2 (T val)
+    {
+        T tally = 0;
+        while (val >>= 1)
+            ++tally;
+        return tally;
+    }
 
 
     //-------------------------------------------------------------------------