| /* |
| * 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. |
| */ |
| |
| /* |
| * Implementation of clz(), which returns the number of leading zero bits, |
| * starting at the most significant bit position. If the argument is zero, |
| * the result is undefined. |
| * |
| * On some platforms, gcc provides a __builtin_clz() function that uses |
| * an optimized implementation (e.g. the CLZ instruction on ARM). |
| * |
| * This gets a little tricky for ARM, because it's only available in ARMv5 |
| * and above, and even on ARMv5 it's not available for THUMB code. So we |
| * need to tailor this for every source file. |
| */ |
| #ifndef _DALVIK_CLZ |
| |
| #if defined(__arm__) && !defined(__thumb__) |
| # include <machine/cpu-features.h> |
| # if defined(__ARM_HAVE_CLZ) |
| # define CLZ(x) __builtin_clz(x) |
| # define HAVE_BUILTIN_CLZ |
| # endif |
| #endif |
| |
| #ifndef HAVE_BUILTIN_CLZ |
| # define CLZ(x) dvmClzImpl(x) |
| int dvmClzImpl(unsigned int x); |
| #endif |
| |
| #endif // _DALVIK_CLZ |
