static int bcsp_recv()

in hci_bcsp.c [580:686]

• 90 lines of code
• 15 McCabe index (conditional complexity)

static int bcsp_recv(struct hci_uart *hu, const void *data, int count)
{
	struct bcsp_struct *bcsp = hu->priv;
	const unsigned char *ptr;

	BT_DBG("hu %p count %d rx_state %d rx_count %ld",
	       hu, count, bcsp->rx_state, bcsp->rx_count);

	ptr = data;
	while (count) {
		if (bcsp->rx_count) {
			if (*ptr == 0xc0) {
				BT_ERR("Short BCSP packet");
				kfree_skb(bcsp->rx_skb);
				bcsp->rx_skb = NULL;
				bcsp->rx_state = BCSP_W4_PKT_START;
				bcsp->rx_count = 0;
			} else
				bcsp_unslip_one_byte(bcsp, *ptr);

			ptr++; count--;
			continue;
		}

		switch (bcsp->rx_state) {
		case BCSP_W4_BCSP_HDR:
			if ((0xff & (u8)~(bcsp->rx_skb->data[0] + bcsp->rx_skb->data[1] +
			    bcsp->rx_skb->data[2])) != bcsp->rx_skb->data[3]) {
				BT_ERR("Error in BCSP hdr checksum");
				kfree_skb(bcsp->rx_skb);
				bcsp->rx_skb = NULL;
				bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
				bcsp->rx_count = 0;
				continue;
			}
			bcsp->rx_state = BCSP_W4_DATA;
			bcsp->rx_count = (bcsp->rx_skb->data[1] >> 4) +
					(bcsp->rx_skb->data[2] << 4);	/* May be 0 */
			continue;

		case BCSP_W4_DATA:
			if (bcsp->rx_skb->data[0] & 0x40) {	/* pkt with crc */
				bcsp->rx_state = BCSP_W4_CRC;
				bcsp->rx_count = 2;
			} else
				bcsp_complete_rx_pkt(hu);
			continue;

		case BCSP_W4_CRC:
			if (bitrev16(bcsp->message_crc) != bscp_get_crc(bcsp)) {
				BT_ERR("Checksum failed: computed %04x received %04x",
				       bitrev16(bcsp->message_crc),
				       bscp_get_crc(bcsp));

				kfree_skb(bcsp->rx_skb);
				bcsp->rx_skb = NULL;
				bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
				bcsp->rx_count = 0;
				continue;
			}
			skb_trim(bcsp->rx_skb, bcsp->rx_skb->len - 2);
			bcsp_complete_rx_pkt(hu);
			continue;

		case BCSP_W4_PKT_DELIMITER:
			switch (*ptr) {
			case 0xc0:
				bcsp->rx_state = BCSP_W4_PKT_START;
				break;
			default:
				/*BT_ERR("Ignoring byte %02x", *ptr);*/
				break;
			}
			ptr++; count--;
			break;

		case BCSP_W4_PKT_START:
			switch (*ptr) {
			case 0xc0:
				ptr++; count--;
				break;

			default:
				bcsp->rx_state = BCSP_W4_BCSP_HDR;
				bcsp->rx_count = 4;
				bcsp->rx_esc_state = BCSP_ESCSTATE_NOESC;
				BCSP_CRC_INIT(bcsp->message_crc);

				/* Do not increment ptr or decrement count
				 * Allocate packet. Max len of a BCSP pkt=
				 * 0xFFF (payload) +4 (header) +2 (crc)
				 */

				bcsp->rx_skb = bt_skb_alloc(0x1005, GFP_ATOMIC);
				if (!bcsp->rx_skb) {
					BT_ERR("Can't allocate mem for new packet");
					bcsp->rx_state = BCSP_W4_PKT_DELIMITER;
					bcsp->rx_count = 0;
					return 0;
				}
				break;
			}
			break;
		}
	}
	return count;
}