mbed-os/drivers/source/usb/LinkedListBase.cpp

86 lines
1.8 KiB
C++

/*
* Copyright (c) 2018-2019, Arm Limited and affiliates.
* SPDX-License-Identifier: Apache-2.0
*
* Licensed 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.
*/
#include "LinkedList.h"
#include "LinkEntry.h"
#include "mbed_assert.h"
LinkedListBase::LinkedListBase(): _head(0), _tail(0)
{
}
LinkedListBase::~LinkedListBase()
{
}
LinkEntry *LinkedListBase::head()
{
return _head;
}
void LinkedListBase::enqueue(LinkEntry *entry)
{
entry->_next = NULL;
if (_tail == NULL) {
_head = entry;
} else {
_tail->_next = entry;
}
_tail = entry;
}
LinkEntry *LinkedListBase::dequeue()
{
if (_head == NULL) {
return NULL;
}
if (_head->_next == NULL) {
_tail = NULL;
}
LinkEntry *entry = _head;
_head = _head->_next;
entry->_next = NULL;
return entry;
}
void LinkedListBase::remove(LinkEntry *entry)
{
LinkEntry *prev = NULL;
LinkEntry *cur = _head;
while (cur != entry) {
if (cur == NULL) {
// Element is not in the list
return;
}
prev = cur;
cur = cur->_next;
}
if (prev != NULL) {
prev->_next = entry->_next;
}
if (entry == _head) {
_head = entry->_next;
}
if (entry == _tail) {
_tail = prev;
}
entry->_next = NULL;
}