233 lines
6.9 KiB
C
233 lines
6.9 KiB
C
/** @file
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* @brief Bluetooth buffer management.
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*/
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/*
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* Copyright (c) 2015 Intel Corporation
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* 1) Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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*
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* 2) Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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*
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* 3) Neither the name of Intel Corporation nor the names of its contributors
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* may be used to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef __BT_BUF_H
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#define __BT_BUF_H
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#include <stddef.h>
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#include <stdint.h>
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/** @def BT_BUF_MAX_DATA
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* @brief Maximum amount of data that can fit in a buffer.
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*
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* The biggest foreseeable buffer size requirement right now comes from
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* the Bluetooth 4.2 SMP MTU which is 65. This then become 65 + 4 (L2CAP
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* header) + 4 (ACL header) + 1 (H4 header) = 74. This also covers the
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* biggest HCI commands and events which are a bit under the 70 byte
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* mark.
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*/
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#define BT_BUF_MAX_DATA 74
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/** Type of data contained in a buffer */
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enum bt_buf_type {
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BT_CMD, /** HCI command */
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BT_EVT, /** HCI event */
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BT_ACL_OUT, /** Outgoing ACL data */
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BT_ACL_IN, /** Incoming ACL data */
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BT_DUMMY = BT_CMD, /** Only used for waking up fibers */
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};
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/** HCI command specific information */
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struct bt_buf_hci_data {
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/** Used by bt_hci_cmd_send_sync. Initially contains the waiting
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* semaphore, as the semaphore is given back contains the bt_buf
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* for the return parameters.
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*/
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void *sync;
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/** The command OpCode that the buffer contains */
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uint16_t opcode;
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};
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/** ACL data buffer specific information */
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struct bt_buf_acl_data {
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uint16_t handle;
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};
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struct bt_buf {
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/** FIFO uses first 4 bytes itself, reserve space */
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int __unused;
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union {
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struct bt_buf_hci_data hci;
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struct bt_buf_acl_data acl;
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};
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/** Pointer to the start of data in the buffer. */
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uint8_t *data;
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/** Length of the data behind the data pointer. */
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uint8_t len;
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uint8_t ref:5, /** Reference count */
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type:3; /** Type of data contained in the buffer */
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/** The full available buffer. */
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uint8_t buf[BT_BUF_MAX_DATA];
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};
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/** @brief Get a new buffer from the pool.
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*
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* Get buffer from the available buffers pool with specified type and
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* reserved headroom.
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*
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* @param type Buffer type.
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* @param reserve_head How much headroom to reserve.
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*
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* @return New buffer or NULL if out of buffers.
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*
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* @warning If there are no available buffers and the function is
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* called from a task or fiber the call will block until a buffer
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* becomes available in the pool.
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*/
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struct bt_buf *bt_buf_get(enum bt_buf_type type, size_t reserve_head);
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/** @brief Decrements the reference count of a buffer.
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*
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* Decrements the reference count of a buffer and puts it back into the
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* pool if the count reaches zero.
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*
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* @param buf Buffer.
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*/
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void bt_buf_put(struct bt_buf *buf);
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/** Increment the reference count of a buffer.
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*
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* Increment the reference count of a buffer.
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*
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* @param buf Buffer.
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*/
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struct bt_buf *bt_buf_hold(struct bt_buf *buf);
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/** @brief Prepare data to be added at the end of the buffer
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*
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* Increments the data length of a buffer to account for more data
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* at the end.
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*
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* @param buf Buffer to update.
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* @param len Number of bytes to increment the length with.
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*
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* @return The original tail of the buffer.
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*/
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void *bt_buf_add(struct bt_buf *buf, size_t len);
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/** @brief Add 16-bit value at the end of the buffer
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*
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* Adds 16-bit value in little endian format at the end of buffer.
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* Increments the data length of a buffer to account for more data
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* at the end.
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*
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* @param buf Buffer to update.
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* @param value 16-bit value to be added.
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*
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* @return void
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*/
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void bt_buf_add_le16(struct bt_buf *buf, uint16_t value);
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/** @brief Push data to the beginning of the buffer.
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*
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* Modifies the data pointer and buffer length to account for more data
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* in the beginning of the buffer.
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*
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* @param buf Buffer to update.
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* @param len Number of bytes to add to the beginning.
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*
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* @return The new beginning of the buffer data.
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*/
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void *bt_buf_push(struct bt_buf *buf, size_t len);
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/** @brief Remove data from the beginning of the buffer.
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*
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* Removes data from the beginnig of the buffer by modifying the data
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* pointer and buffer length.
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*
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* @param buf Buffer to update.
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* @param len Number of bytes to remove.
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*
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* @return New beginning of the buffer data.
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*/
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void *bt_buf_pull(struct bt_buf *buf, size_t len);
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/** @brief Remove and convert 16 bits from the beginning of the buffer.
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*
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* Same idea as with bt_buf_pull(), but a helper for operating on
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* 16-bit little endian data.
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*
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* @param buf Buffer.
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*
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* @return 16-bit value converted from little endian to host endian.
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*/
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uint16_t bt_buf_pull_le16(struct bt_buf *buf);
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/** @brief Check buffer tailroom.
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*
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* Check how much free space there is at the end of the buffer.
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*
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* @return Number of bytes available at the end of the buffer.
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*/
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size_t bt_buf_tailroom(struct bt_buf *buf);
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/** @brief Check buffer headroom.
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*
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* Check how much free space there is in the beginning of the buffer.
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*
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* @return Number of bytes available in the beginning of the buffer.
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*/
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size_t bt_buf_headroom(struct bt_buf *buf);
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/** @def bt_buf_tail
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* @brief Get the tail pointer for a buffer.
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*
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* Get a pointer to the end of the data in a buffer.
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*
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* @param buf Buffer.
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*
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* @return Tail pointer for the buffer.
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*/
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#define bt_buf_tail(buf) ((buf)->data + (buf)->len)
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/** @brief Initialize buffer handling.
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*
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* Initialize the buffers with specified amount of incoming and outgoing
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* ACL buffers. The HCI command and event buffers will be allocated from
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* whatever is left over.
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*
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* @param acl_in Number of incoming ACL data buffers.
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* @param acl_out Number of outgoing ACL data buffers.
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*
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* @return Zero on success or (negative) error code on failure.
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*/
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int bt_buf_init(int acl_in, int acl_out);
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#endif /* __BT_BUF_H */
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