C++ CIRC_SPACE函数代码示例

/*
 * wait for space to appear in the transmit/ACK window
 * - caller holds the socket locked
 */
static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx,
				    struct rxrpc_call *call,
				    long *timeo)
{
	DECLARE_WAITQUEUE(myself, current);
	int ret;

	_enter(",{%d},%ld",
	       CIRC_SPACE(call->acks_head, call->acks_tail, call->acks_winsz),
	       *timeo);

	add_wait_queue(&call->tx_waitq, &myself);

	for (;;) {
		set_current_state(TASK_INTERRUPTIBLE);
		ret = 0;
		if (CIRC_SPACE(call->acks_head, call->acks_tail,
			       call->acks_winsz) > 0)
			break;
		if (signal_pending(current)) {
			ret = sock_intr_errno(*timeo);
			break;
		}

		release_sock(&rx->sk);
		*timeo = schedule_timeout(*timeo);
		lock_sock(&rx->sk);
	}

	remove_wait_queue(&call->tx_waitq, &myself);
	set_current_state(TASK_RUNNING);
	_leave(" = %d", ret);
	return ret;
}

static int rs_put_char(struct tty_struct *tty, unsigned char ch)
{
	struct serial_state *info;
	unsigned long flags;

	info = tty->driver_data;

	if (serial_paranoia_check(info, tty->name, "rs_put_char"))
		return 0;

	if (!info->xmit.buf)
		return 0;

	local_irq_save(flags);
	if (CIRC_SPACE(info->xmit.head,
		       info->xmit.tail,
		       SERIAL_XMIT_SIZE) == 0) {
		local_irq_restore(flags);
		return 0;
	}

	info->xmit.buf[info->xmit.head++] = ch;
	info->xmit.head &= SERIAL_XMIT_SIZE-1;
	local_irq_restore(flags);
	return 1;
}

static void ev3_uart_receive_buf(struct tty_struct *tty,
				 const unsigned char *cp, char *fp, int count)
{
	struct ev3_uart_port_data *port = tty->disc_data;
	struct circ_buf *cb = &port->circ_buf;
	int size;

	if (port->closing)
		return;

	if (count > CIRC_SPACE(cb->head, cb->tail, EV3_UART_BUFFER_SIZE))
		return;

	size = CIRC_SPACE_TO_END(cb->head, cb->tail, EV3_UART_BUFFER_SIZE);
	if (count > size) {
		memcpy(cb->buf + cb->head, cp, size);
		memcpy(cb->buf, cp + size, count - size);
		cb->head = count - size;
	} else {
		memcpy(cb->buf + cb->head, cp, count);
		cb->head += count;
	}

	schedule_work(&port->rx_data_work);
}

/********************************************************************************
 *  Description:
 *   Input Args:
 *  Output Args:
 * Return Value:
 ********************************************************************************/
int main (int argc, char **argv)
{
    int i, len;
    struct circ_buf        tx_ring; 
    char   data[LEN];
    char   buf[LEN];

    memset(&tx_ring, 0, sizeof(struct circ_buf)); 
    tx_ring.buf = malloc(CIRC_BUF_SIZE); 
    if( NULL == tx_ring.buf )
    {
        printf("Allocate Ring buffer failure.\n");
        return -1;
    }

    memset(data, 0, sizeof(data));
    /* Prepare for the data */
    for(i=0; i<sizeof(data); i++)
    {
        data[i] = 30+i;
    }

    printf("CIRC_SPACE: %d\n", CIRC_SPACE(tx_ring.head, tx_ring.tail, CIRC_BUF_SIZE));
    printf("CIRC_SPACE_TO_END: %d\n", CIRC_SPACE_TO_END(tx_ring.head, tx_ring.tail, CIRC_BUF_SIZE));
    printf("CIRC_CNT: %d\n", CIRC_CNT(tx_ring.head, tx_ring.tail, CIRC_BUF_SIZE));
    printf("CIRC_CNT_TO_END: %d\n", CIRC_CNT_TO_END(tx_ring.head, tx_ring.tail, CIRC_BUF_SIZE));
    while(1)
    {
       produce_item(&tx_ring, data, sizeof(data));
       len = consume_item(&tx_ring, buf, sizeof(buf) );
       sleep(1);
    }

    return 0;
} /* ----- End of main() ----- */

/* -1 --- error, can't enqueue -- no space available */
static int jr_enqueue(uint32_t *desc_addr,
	       void (*callback)(uint32_t desc, uint32_t status, void *arg),
	       void *arg)
{
	struct jr_regs *regs = (struct jr_regs *)CONFIG_SYS_FSL_JR0_ADDR;
	int head = jr.head;
	dma_addr_t desc_phys_addr = virt_to_phys(desc_addr);

	if (sec_in32(&regs->irsa) == 0 ||
	    CIRC_SPACE(jr.head, jr.tail, jr.size) <= 0)
		return -1;

	jr.input_ring[head] = desc_phys_addr;
	jr.info[head].desc_phys_addr = desc_phys_addr;
	jr.info[head].desc_addr = (uint32_t)desc_addr;
	jr.info[head].callback = (void *)callback;
	jr.info[head].arg = arg;
	jr.info[head].op_done = 0;

	jr.head = (head + 1) & (jr.size - 1);

	sec_out32(&regs->irja, 1);

	return 0;
}

static int qtnf_tx_queue_ready(struct qtnf_pcie_bus_priv *priv)
{
	if (!CIRC_SPACE(priv->tx_bd_w_index, priv->tx_bd_r_index,
			priv->tx_bd_num)) {
		qtnf_pcie_data_tx_reclaim(priv);

		if (!CIRC_SPACE(priv->tx_bd_w_index, priv->tx_bd_r_index,
				priv->tx_bd_num)) {
			pr_warn_ratelimited("reclaim full Tx queue\n");
			priv->tx_full_count++;
			return 0;
		}
	}

	return 1;
}

static int qtnf_dbg_hdp_stats(struct seq_file *s, void *data)
{
	struct qtnf_bus *bus = dev_get_drvdata(s->private);
	struct qtnf_pcie_pearl_state *ps = get_bus_priv(bus);
	struct qtnf_pcie_bus_priv *priv = &ps->base;

	seq_printf(s, "tx_full_count(%u)\n", priv->tx_full_count);
	seq_printf(s, "tx_done_count(%u)\n", priv->tx_done_count);
	seq_printf(s, "tx_reclaim_done(%u)\n", priv->tx_reclaim_done);
	seq_printf(s, "tx_reclaim_req(%u)\n", priv->tx_reclaim_req);

	seq_printf(s, "tx_bd_r_index(%u)\n", priv->tx_bd_r_index);
	seq_printf(s, "tx_bd_p_index(%u)\n",
		   readl(PCIE_HDP_RX0DMA_CNT(ps->pcie_reg_base))
			& (priv->tx_bd_num - 1));
	seq_printf(s, "tx_bd_w_index(%u)\n", priv->tx_bd_w_index);
	seq_printf(s, "tx queue len(%u)\n",
		   CIRC_CNT(priv->tx_bd_w_index, priv->tx_bd_r_index,
			    priv->tx_bd_num));

	seq_printf(s, "rx_bd_r_index(%u)\n", priv->rx_bd_r_index);
	seq_printf(s, "rx_bd_p_index(%u)\n",
		   readl(PCIE_HDP_TX0DMA_CNT(ps->pcie_reg_base))
			& (priv->rx_bd_num - 1));
	seq_printf(s, "rx_bd_w_index(%u)\n", priv->rx_bd_w_index);
	seq_printf(s, "rx alloc queue len(%u)\n",
		   CIRC_SPACE(priv->rx_bd_w_index, priv->rx_bd_r_index,
			      priv->rx_bd_num));

	return 0;
}

static void hisi_femac_rx_refill(struct hisi_femac_priv *priv)
{
	struct hisi_femac_queue *rxq = &priv->rxq;
	struct sk_buff *skb;
	u32 pos;
	u32 len = MAX_FRAME_SIZE;
	dma_addr_t addr;

	pos = rxq->head;
	while (readl(priv->port_base + ADDRQ_STAT) & BIT_RX_READY) {
		if (!CIRC_SPACE(pos, rxq->tail, rxq->num))
			break;
		if (unlikely(rxq->skb[pos])) {
			netdev_err(priv->ndev, "err skb[%d]=%p\n",
				   pos, rxq->skb[pos]);
			break;
		}
		skb = netdev_alloc_skb_ip_align(priv->ndev, len);
		if (unlikely(!skb))
			break;

		addr = dma_map_single(priv->dev, skb->data, len,
				      DMA_FROM_DEVICE);
		if (dma_mapping_error(priv->dev, addr)) {
			dev_kfree_skb_any(skb);
			break;
		}
		rxq->dma_phys[pos] = addr;
		rxq->skb[pos] = skb;
		writel(addr, priv->port_base + IQ_ADDR);
		pos = (pos + 1) % rxq->num;
	}
	rxq->head = pos;
}

static int rs_write_room(struct tty_struct *tty)
{
	struct serial_state *info = tty->driver_data;

	if (serial_paranoia_check(info, tty->name, "rs_write_room"))
		return 0;
	return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
}

//-----------------------------------------------------------------------------
/// Return current load of TX.
//-----------------------------------------------------------------------------
unsigned int EMAC_TxLoad(void)
{
    unsigned short head = txTd.head;
    unsigned short tail = txTd.tail;
  #if 1
    return CIRC_CNT(head, tail, TX_BUFFERS);
  #else
    return (TX_BUFFERS - CIRC_SPACE(head, tail, TX_BUFFERS));
  #endif
}

//////////////////////////////////////////////////////////////////////////////
// ASYNCHRONOUS
//////////////////////////////////////////////////////////////////////////////
static  void kick_start_rx( void )
{
	 if ( usb_ref_count ) {
		  int total_space  = CIRC_SPACE( rx_ring.in, rx_ring.out, RBUF_SIZE );
		  if ( total_space >= RX_PACKET_SIZE ) {
			   pxa_usb_recv( packet_buffer,
								RX_PACKET_SIZE,
								rx_done_callback_packet_buffer
						      );
		  }
	 }
}

/*
 * Return the amount of space in the output buffer
 *
 * This is actually a contract between the driver and the tty layer outlining
 * how much write room the driver can guarantee will be sent OR BUFFERED.  This
 * driver MUST honor the return value.
 */
static int ehv_bc_tty_write_room(struct tty_struct *ttys)
{
	struct ehv_bc_data *bc = ttys->driver_data;
	unsigned long flags;
	int count;

	spin_lock_irqsave(&bc->lock, flags);
	count = CIRC_SPACE(bc->head, bc->tail, BUF_SIZE);
	spin_unlock_irqrestore(&bc->lock, flags);

	return count;
}

static void user_notify_callback(void *event)
{
	down(&event_mutex);
	if (CIRC_SPACE(pmic_events.head, pmic_events.tail, CIRC_BUF_MAX)) {
		pmic_events.buf[pmic_events.head] = (int)event;
		pmic_events.head = (pmic_events.head + 1) & (CIRC_BUF_MAX - 1);
	} else {
		pr_info("Failed to notify event to the user\n");
	}
	up(&event_mutex);

	kill_fasync(&pmic_dev_queue, SIGIO, POLL_IN);
}

void put_to_in(forth_context_type *fc, char c)
{
	set_current_state(TASK_INTERRUPTIBLE);
	while (CIRC_SPACE(fc->in.head,fc->in.tail,TIB_SIZE)==0)
	{
		schedule_timeout(1);
		set_current_state(TASK_INTERRUPTIBLE);
		if(fc->stop) return;
	}
	set_current_state(TASK_RUNNING);
	fc->in.buf[fc->in.head]=c;
	fc->in.head=(fc->in.head+1) & (TIB_SIZE-1);
}

static netdev_tx_t hisi_femac_net_xmit(struct sk_buff *skb,
				       struct net_device *dev)
{
	struct hisi_femac_priv *priv = netdev_priv(dev);
	struct hisi_femac_queue *txq = &priv->txq;
	dma_addr_t addr;
	u32 val;

	val = readl(priv->port_base + ADDRQ_STAT);
	val &= BIT_TX_READY;
	if (!val) {
		hisi_femac_irq_enable(priv, IRQ_INT_TX_PER_PACKET);
		dev->stats.tx_dropped++;
		dev->stats.tx_fifo_errors++;
		netif_stop_queue(dev);
		return NETDEV_TX_BUSY;
	}

	if (unlikely(!CIRC_SPACE(txq->head, txq->tail,
				 txq->num))) {
		hisi_femac_irq_enable(priv, IRQ_INT_TX_PER_PACKET);
		dev->stats.tx_dropped++;
		dev->stats.tx_fifo_errors++;
		netif_stop_queue(dev);
		return NETDEV_TX_BUSY;
	}

	addr = dma_map_single(priv->dev, skb->data,
			      skb->len, DMA_TO_DEVICE);
	if (unlikely(dma_mapping_error(priv->dev, addr))) {
		dev_kfree_skb_any(skb);
		dev->stats.tx_dropped++;
		return NETDEV_TX_OK;
	}
	txq->dma_phys[txq->head] = addr;

	txq->skb[txq->head] = skb;
	txq->head = (txq->head + 1) % txq->num;

	writel(addr, priv->port_base + EQ_ADDR);
	writel(skb->len + ETH_FCS_LEN, priv->port_base + EQFRM_LEN);

	priv->tx_fifo_used_cnt++;

	dev->stats.tx_packets++;
	dev->stats.tx_bytes += skb->len;
	netdev_sent_queue(dev, skb->len);

	return NETDEV_TX_OK;
}