From 11c7e561fc29b56ade8ae6ec549b21c533540e8a Mon Sep 17 00:00:00 2001
From: Martin Braun <martin.braun@ettus.com>
Date: Tue, 15 Jan 2019 14:42:05 -0800
Subject: math: Remove uhd::math::log2, replace with std::log2

Now that we're C++11, we can assume the existence of said symbol and
need no more portability hacks.
---
 host/cmake/Modules/UHDGlobalDefs.cmake  | 3 ---
 host/include/uhd/utils/math.hpp         | 9 ---------
 host/lib/usrp/common/ad936x_manager.cpp | 3 ++-
 host/tests/math_test.cpp                | 9 +++------
 4 files changed, 5 insertions(+), 19 deletions(-)

(limited to 'host')

diff --git a/host/cmake/Modules/UHDGlobalDefs.cmake b/host/cmake/Modules/UHDGlobalDefs.cmake
index 47bb83511..385679258 100644
--- a/host/cmake/Modules/UHDGlobalDefs.cmake
+++ b/host/cmake/Modules/UHDGlobalDefs.cmake
@@ -9,9 +9,6 @@
 
 include(CheckCXXSymbolExistsCopy)
 
-## Check for std::log2
-CHECK_CXX_SYMBOL_EXISTS(log2 cmath HAVE_LOG2)
-
 ## Macros for the version number
 if(UHD_VERSION_DEVEL)
     math(EXPR UHD_VERSION_ADDED "1000000 * ${UHD_VERSION_MAJOR} + 10000 * ${UHD_VERSION_API} + 100 * ${UHD_VERSION_ABI} + 99")
diff --git a/host/include/uhd/utils/math.hpp b/host/include/uhd/utils/math.hpp
index e9f8efb57..8606923fa 100644
--- a/host/include/uhd/utils/math.hpp
+++ b/host/include/uhd/utils/math.hpp
@@ -223,15 +223,6 @@ UHD_INLINE bool frequencies_are_equal(double lhs, double rhs)
             == fp_compare::fp_compare_delta<double>(rhs, FREQ_COMPARISON_DELTA_HZ));
 }
 
-//! Portable log2()
-template <typename float_t> UHD_INLINE float_t log2(float_t x)
-{
-    // C++11 defines std::log2(), when that's universally supported
-    // we can switch over.
-    return std::log(x) / std::log(float_t(2));
-}
-
-
 } // namespace math
 } // namespace uhd
 
diff --git a/host/lib/usrp/common/ad936x_manager.cpp b/host/lib/usrp/common/ad936x_manager.cpp
index 87521e834..5c4cb51ae 100644
--- a/host/lib/usrp/common/ad936x_manager.cpp
+++ b/host/lib/usrp/common/ad936x_manager.cpp
@@ -10,6 +10,7 @@
 #include <boost/functional/hash.hpp>
 #include <boost/make_shared.hpp>
 #include <chrono>
+#include <cmath>
 #include <thread>
 
 using namespace uhd;
@@ -167,7 +168,7 @@ public:
         // We use shifts here instead of 2^x because exp2() is not available in all
         // compilers, also this guarantees no rounding issues. The type cast to int32_t
         // serves as floor():
-        int32_t multiplier = (1 << int32_t(uhd::math::log2(max_tick_rate / lcm_rate)));
+        int32_t multiplier = (1 << int32_t(std::log2(max_tick_rate / lcm_rate)));
         if (multiplier == 2 and lcm_rate >= min_tick_rate) {
             // Don't bother (see above)
             multiplier = 1;
diff --git a/host/tests/math_test.cpp b/host/tests/math_test.cpp
index ffdcbb086..575cfe071 100644
--- a/host/tests/math_test.cpp
+++ b/host/tests/math_test.cpp
@@ -9,11 +9,8 @@
 #include <stdint.h>
 #include <boost/test/unit_test.hpp>
 
-// NOTE: This is not the only math test case, see e.g. special tests
-// for fp comparison.
-
-BOOST_AUTO_TEST_CASE(test_log2)
+// We need an empty test
+BOOST_AUTO_TEST_CASE(test_)
 {
-    double y = uhd::math::log2(16.0);
-    BOOST_CHECK_EQUAL(y, 4.0);
+    BOOST_CHECK_EQUAL(true, true);
 }
-- 
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