56 lines
1.8 KiB
C
56 lines
1.8 KiB
C
/****************************************************************************
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* libs/libc/string/lib_popcount.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. 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, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/compiler.h>
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#include <strings.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: popcount
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****************************************************************************/
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unsigned int popcount(unsigned int j)
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{
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#ifdef CONFIG_HAVE_BUILTIN_POPCOUNT
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return __builtin_popcount(j);
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#else
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unsigned int count = 0;
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while (j > 0)
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{
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if ((j & 1) == 1)
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{
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count++;
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}
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j >>= 1;
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}
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return count;
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#endif
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}
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