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-rw-r--r--include/mbgl/math/log2.hpp16
1 files changed, 16 insertions, 0 deletions
diff --git a/include/mbgl/math/log2.hpp b/include/mbgl/math/log2.hpp
index 6a1ba23ed9..3136ac22b4 100644
--- a/include/mbgl/math/log2.hpp
+++ b/include/mbgl/math/log2.hpp
@@ -2,6 +2,11 @@
#include <cmath>
#include <cstdint>
+#include <type_traits>
+
+#if defined(__ANDROID__)
+#include <android/api-level.h>
+#endif
namespace mbgl {
namespace util {
@@ -12,3 +17,14 @@ uint32_t ceil_log2(uint64_t x);
} // namespace util
} // namespace mbgl
+
+// log2 is not available on Android before API 18.
+#if defined(__ANDROID__) && defined(__GNUC__) && \
+ defined(__ANDROID_API__) && __ANDROID_API__ < 18
+
+template <typename T>
+typename std::enable_if_t<std::is_floating_point<T>::value, T> log2(T x) {
+ return ::log(x) / M_LN2;
+}
+
+#endif