incubator-nuttx/libs/libc/queue/sq_remlast.c

69 lines
2.1 KiB
C

/****************************************************************************
* libs/libc/queue/sq_remlast.c
*
* 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.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <queue.h>
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: sq_remlast
*
* Description:
* Removes the last entry in a singly-linked queue.
*
****************************************************************************/
FAR sq_entry_t *sq_remlast(sq_queue_t *queue)
{
FAR sq_entry_t *ret = queue->tail;
if (ret)
{
if (queue->head == queue->tail)
{
queue->head = NULL;
queue->tail = NULL;
}
else
{
FAR sq_entry_t *prev;
for (prev = queue->head;
prev && prev->flink != ret;
prev = prev->flink);
if (prev)
{
prev->flink = NULL;
queue->tail = prev;
}
}
ret->flink = NULL;
}
return ret;
}