b87804c2ba
In the gcc-riscv compiler, __builtin_ffs will call ffs, and calling __builtin_ffs in ffs will cause recursion Change ffs to an inline function, and compile ffs implemented by nuttx by default. Only call the implementation of nuttx when the compiler cannot provide an ffs implementation. Signed-off-by: yinshengkai <yinshengkai@xiaomi.com>
66 lines
2.2 KiB
C
66 lines
2.2 KiB
C
/****************************************************************************
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* libs/libc/string/lib_flsl.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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* Pre-processor Definitions
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****************************************************************************/
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#define NBITS (8 * sizeof(unsigned long))
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: flsl
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*
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* Description:
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* The flsl() function will find the last bit set in value and return
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* the index of that bit. Bits are numbered starting at one (the least
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* significant bit).
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*
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* Returned Value:
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* The flsl() function will return the index of the last bit set. If j is
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* 0, then flsl() will return 0.
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*
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****************************************************************************/
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int flsl(long j)
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{
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int ret = 0;
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if (j != 0)
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{
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unsigned long value = (unsigned long)j;
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int bitno;
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for (bitno = 1; bitno <= NBITS; bitno++, value >>= 1)
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{
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if (value == 1)
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{
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ret = bitno;
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break;
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}
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}
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}
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return ret;
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}
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