音视频传输，音频优先传输之队列

typedef struct 
{
    unsigned char *Buff;
    unsigned int Head;
    unsigned int Tail;
    unsigned int Len;
    unsigned int VaildLen;
    unsigned int InvaildLen;
}QUEUE_S;

char USER_QueueInit(QUEUE_S *pq, unsigned long buff_size);//初始化队列  
void USER_QueueDestroy( QUEUE_S* pq ); //销毁队列
char USER_QueuePush( QUEUE_S* pq, const unsigned char* dat, unsigned int len );//入队  
unsigned int USER_QueueGetTop(QUEUE_S *pq, unsigned char *rtval, unsigned int len);//获取队头的值，但不删除,返回从队列中读取的字节数 
void USER_QueuePop(QUEUE_S *pq, unsigned int len);//出队  
unsigned int USER_QueueGetVaildLenght(QUEUE_S* pq);
char USER_QueueIsFull(QUEUE_S *pq);
char USER_QueueIsEmpty(QUEUE_S *pq);


char USER_QueueInit( QUEUE_S* pq, unsigned long buff_size ) //初始化队列
{
    pq->Buff = ( HI_U8* )malloc( sizeof( HI_U8 ) * buff_size );
    if ( NULL == pq->Buff )
    {
        printf( "%s: malloc failed!\n", __FUNCTION__ );
        return -1;
    }
    pq->Head = 0;
    pq->Tail = 0;
    pq->Len = buff_size;
    pq->VaildLen = 0;
    pq->InvaildLen = buff_size - 1;     //队列头前面一个字节不能存放数据，如果存了，头跟尾指向同一个地方
    
    return 0;
}

void USER_QueueDestroy( QUEUE_S* pq ) //销毁队列
{
    free(pq->Buff);
}


char USER_QueuePush( QUEUE_S* pq, const unsigned char* dat, unsigned int len ) //入队
{
    unsigned int i;

    if ( ( USER_QueueIsFull( pq ) ) || ( pq->InvaildLen < len ) )
    {
        return -1;
    }
    for( i = 0; i < len; i++ )
    {
        pq->Buff[pq->Tail] = dat[i];
        pq->Tail = ( pq->Tail + 1 ) % pq->Len;
    }

    pq->VaildLen += len;
    pq->InvaildLen = pq->InvaildLen - len;
    return 0;
}


unsigned int USER_QueueGetTop( QUEUE_S* pq, unsigned char *rtval, unsigned int len ) //获取队头的值，但不删除
{
    unsigned int temp, i;
    unsigned int temp_Head = pq->Head;

    if ( USER_QueueIsEmpty( pq ) )
    {
        return 0;
    }

    if( ( pq->Len - pq->InvaildLen - 1) < len )
    {
        temp = pq->Len - pq->InvaildLen -1;
    }
    else
    {
        temp = len;
    }

    for( i = 0; i < temp; i++ )
    {
        rtval[i] = pq->Buff[temp_Head];
        temp_Head = ( temp_Head + 1 ) % pq->Len;
    }

    return temp;
}


void USER_QueuePop( QUEUE_S* pq, unsigned int len ) //出队
{
    if ( USER_QueueIsEmpty( pq ) )
    {
        return;
    }

    if( pq->VaildLen <= len )
    {
        pq->Head = pq->Tail;
        pq->VaildLen = 0;
        //队列头前面一个字节不能存放数据，如果存了，头跟尾指向同一个地方
        pq->InvaildLen = pq->Len-1;
    }
    else
    {
        pq->Head = ( pq->Head + len ) % pq->Len;
        pq->VaildLen -= len;
        pq->InvaildLen += len;
    }
}


unsigned int USER_QueueGetVaildLenght(QUEUE_S* pq)
{
    return pq->VaildLen;
}
char USER_QueueIsFull( QUEUE_S* pq )
{
    return ( pq->Tail + 1 ) % pq->Len == pq->Head;
}
char USER_QueueIsEmpty( QUEUE_S* pq )
{
    return pq->Tail == pq->Head;;
}