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