nci/jni/DataQueue.cpp

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * 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.
 */

/*
 *  Store data bytes in a variable-size queue.
 */

#include "DataQueue.h"


/*******************************************************************************
**
** Function:        DataQueue
**
** Description:     Initialize member variables.
**
** Returns:         None.
**
*******************************************************************************/
DataQueue::DataQueue ()
{
}


/*******************************************************************************
**
** Function:        ~DataQueue
**
** Description:      Release all resources.
**
** Returns:         None.
**
*******************************************************************************/
DataQueue::~DataQueue ()
{
    mMutex.lock ();
    while (mQueue.empty() == false)
    {
        tHeader* header = mQueue.front ();
        mQueue.pop_front ();
        free (header);
    }
    mMutex.unlock ();
}


bool DataQueue::isEmpty()
{
    mMutex.lock ();
    bool retval = mQueue.empty();
    mMutex.unlock ();
    return retval;
}


/*******************************************************************************
**
** Function:        enqueue
**
** Description:     Append data to the queue.
**                  data: array of bytes
**                  dataLen: length of the data.
**
** Returns:         True if ok.
**
*******************************************************************************/
bool DataQueue::enqueue (UINT8* data, UINT16 dataLen)
{
    if ((data == NULL) || (dataLen==0))
        return false;

    mMutex.lock ();

    bool retval = false;
    tHeader* header = (tHeader*) malloc (sizeof(tHeader) + dataLen);

    if (header)
    {
        memset (header, 0, sizeof(tHeader));
        header->mDataLen = dataLen;
        memcpy (header+1, data, dataLen);

        mQueue.push_back (header);

        retval = true;
    }
    else
    {
        ALOGE ("DataQueue::enqueue: out of memory ?????");
    }
    mMutex.unlock ();
    return retval;
}


/*******************************************************************************
**
** Function:        dequeue
**
** Description:     Retrieve and remove data from the front of the queue.
**                  buffer: array to store the data.
**                  bufferMaxLen: maximum size of the buffer.
**                  actualLen: actual length of the data.
**
** Returns:         True if ok.
**
*******************************************************************************/
bool DataQueue::dequeue (UINT8* buffer, UINT16 bufferMaxLen, UINT16& actualLen)
{
    mMutex.lock ();

    tHeader* header = mQueue.front ();
    bool retval = false;

    if (header && buffer && (bufferMaxLen>0))
    {
        if (header->mDataLen <= bufferMaxLen)
        {
            //caller's buffer is big enough to store all data
            actualLen = header->mDataLen;
            char* src = (char*)(header) + sizeof(tHeader) + header->mOffset;
            memcpy (buffer, src, actualLen);

            mQueue.pop_front ();
            free (header);
        }
        else
        {
            //caller's buffer is too small
            actualLen = bufferMaxLen;
            char* src = (char*)(header) + sizeof(tHeader) + header->mOffset;
            memcpy (buffer, src, actualLen);
            //adjust offset so the next dequeue() will get the remainder
            header->mDataLen -= actualLen;
            header->mOffset += actualLen;
        }
        retval = true;
    }
    mMutex.unlock ();
    return retval;
}