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authorLeith Bade <leith@mapbox.com>2014-12-05 23:16:49 +1100
committerLeith Bade <leith@mapbox.com>2014-12-05 23:16:49 +1100
commitde9eb00276684a10f49a1c490f55266b80238155 (patch)
treefc713b06541bb1af04e95c70f2e383bcb86a164a /src/mbgl/util/math.cpp
parentc348c141c5c5754c962d9b7e94af83f097e30487 (diff)
parentff640132de0fe855314a8fd86adae3a2fb33237b (diff)
downloadqtlocation-mapboxgl-de9eb00276684a10f49a1c490f55266b80238155.tar.gz
Merge branch 'master' of github.com:mapbox/mapbox-gl-native into android-mason
Conflicts: .gitignore gyp/mbgl-ios.gypi gyp/mbgl-linux.gypi gyp/mbgl-osx.gypi include/mbgl/map/map.hpp src/mbgl/map/map.cpp src/mbgl/storage/caching_http_file_source.cpp
Diffstat (limited to 'src/mbgl/util/math.cpp')
-rw-r--r--src/mbgl/util/math.cpp25
1 files changed, 25 insertions, 0 deletions
diff --git a/src/mbgl/util/math.cpp b/src/mbgl/util/math.cpp
new file mode 100644
index 0000000000..a7eab2d771
--- /dev/null
+++ b/src/mbgl/util/math.cpp
@@ -0,0 +1,25 @@
+#include <mbgl/util/math.hpp>
+
+namespace mbgl {
+namespace util {
+
+// From http://stackoverflow.com/questions/3272424/compute-fast-log-base-2-ceiling
+uint32_t ceil_log2(uint64_t x) {
+ static const uint64_t t[6] = {0xFFFFFFFF00000000, 0x00000000FFFF0000,
+ 0x000000000000FF00, 0x00000000000000F0,
+ 0x000000000000000C, 0x0000000000000002};
+ uint32_t y = (((x & (x - 1)) == 0) ? 0 : 1);
+ uint32_t j = 32;
+
+ for (int32_t i = 0; i < 6; i++) {
+ const uint32_t k = (((x & t[i]) == 0) ? 0 : j);
+ y += k;
+ x >>= k;
+ j >>= 1;
+ }
+
+ return y;
+}
+
+}
+} \ No newline at end of file