Initial Contribution

1 files changed, 37 insertions, 0 deletions

diff --git a/libs/surfaceflinger/clz.cpp b/libs/surfaceflinger/clz.cpp
new file mode 100644
index 000000000000..2456b86aca27
--- /dev/null
+++ b/libs/surfaceflinger/clz.cpp
@@ -0,0 +1,37 @@
+/*
+ * Copyright (C) 2007 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "clz.h"
+
+namespace android {
+
+int clz_impl(int32_t x)
+{
+#if defined(__arm__) && !defined(__thumb__)
+    return __builtin_clz(x);
+#else
+    if (!x) return 32;
+    int e = 31;
+    if (x&0xFFFF0000)   { e -=16; x >>=16; }
+    if (x&0x0000FF00)   { e -= 8; x >>= 8; }
+    if (x&0x000000F0)   { e -= 4; x >>= 4; }
+    if (x&0x0000000C)   { e -= 2; x >>= 2; }
+    if (x&0x00000002)   { e -= 1; }
+    return e;
+#endif
+}
+
+}; // namespace android