1 /* 2 * Copyright (C) 2007 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 #include "clz.h" 18 19 namespace android { 20 21 int clz_impl(int32_t x) 22 { 23 #if defined(__arm__) && !defined(__thumb__) 24 return __builtin_clz(x); 25 #else 26 if (!x) return 32; 27 int e = 31; 28 if (x&0xFFFF0000) { e -=16; x >>=16; } 29 if (x&0x0000FF00) { e -= 8; x >>= 8; } 30 if (x&0x000000F0) { e -= 4; x >>= 4; } 31 if (x&0x0000000C) { e -= 2; x >>= 2; } 32 if (x&0x00000002) { e -= 1; } 33 return e; 34 #endif 35 } 36 37 }; // namespace android 38
