blob: 2456b86aca273f231634f24698946f99f1847a12 [file] [log] [blame]
The Android Open Source Projectedbf3b62009-03-03 19:31:44 -08001/*
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
19namespace android {
20
21int 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