68 lines
2.2 KiB
C
68 lines
2.2 KiB
C
/****************************************************************************
|
|
* libs/libc/string/lib_flsl.c
|
|
*
|
|
* SPDX-License-Identifier: Apache-2.0
|
|
*
|
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
|
* contributor license agreements. See the NOTICE file distributed with
|
|
* this work for additional information regarding copyright ownership. The
|
|
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
|
* "License"); you may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
* License for the specific language governing permissions and limitations
|
|
* under the License.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Pre-processor Definitions
|
|
****************************************************************************/
|
|
|
|
#define NBITS (8 * sizeof(unsigned long))
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: flsl
|
|
*
|
|
* Description:
|
|
* The flsl() function will find the last bit set in value and return
|
|
* the index of that bit. Bits are numbered starting at one (the least
|
|
* significant bit).
|
|
*
|
|
* Returned Value:
|
|
* The flsl() function will return the index of the last bit set. If j is
|
|
* 0, then flsl() will return 0.
|
|
*
|
|
****************************************************************************/
|
|
|
|
int flsl(long j)
|
|
{
|
|
int ret = 0;
|
|
|
|
if (j != 0)
|
|
{
|
|
unsigned long value = (unsigned long)j;
|
|
int bitno;
|
|
|
|
for (bitno = 1; bitno <= NBITS; bitno++, value >>= 1)
|
|
{
|
|
if (value == 1)
|
|
{
|
|
ret = bitno;
|
|
break;
|
|
}
|
|
}
|
|
}
|
|
|
|
return ret;
|
|
}
|