| The Android Open Source Project | edbf3b6 | 2009-03-03 19:31:44 -0800 | [diff] [blame] | 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 |