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Bluetooth: Assert alignof bt_addr types

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I got some feedback about confusion as to why the bt_addr types are not
packed. This commit adds a note about it.

This commit also adds a check for the alignof of the structs to verify
the statement 'their members are bytes or byte arrays' to thoroughly
prove that the struct is effectively as-if packed.

Signed-off-by: Aleksander Wasaznik <aleksander.wasaznik@nordicsemi.no>
This commit is contained in:
Aleksander Wasaznik 2024-04-10 21:37:51 +02:00 • committed by Carles Cufí
commit 2ec7a46d0f
1 changed files with 8 additions and 0 deletions
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8
subsys/bluetooth/common/dummy.c
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@ -9,6 +9,8 @@
* SPDX-License-Identifier: Apache-2.0 * SPDX-License-Identifier: Apache-2.0
*/ */
#include <stdalign.h>
#include <zephyr/kernel.h> #include <zephyr/kernel.h>
#include <zephyr/bluetooth/bluetooth.h> #include <zephyr/bluetooth/bluetooth.h>
@ -18,9 +20,15 @@
* their members are bytes or byte arrays, the size is. They must not be padded * their members are bytes or byte arrays, the size is. They must not be padded
* by the compiler, otherwise the on-wire packet will not map the packed * by the compiler, otherwise the on-wire packet will not map the packed
* structure correctly. * structure correctly.
*
* The bt_addr structs are not marked __packed because it's considered ugly by
* some. But here is a proof that the structs have all the properties of, and
* can be safely used as packed structs.
*/ */
BUILD_ASSERT(sizeof(bt_addr_t) == BT_ADDR_SIZE); BUILD_ASSERT(sizeof(bt_addr_t) == BT_ADDR_SIZE);
BUILD_ASSERT(alignof(bt_addr_t) == 1);
BUILD_ASSERT(sizeof(bt_addr_le_t) == BT_ADDR_LE_SIZE); BUILD_ASSERT(sizeof(bt_addr_le_t) == BT_ADDR_LE_SIZE);
BUILD_ASSERT(alignof(bt_addr_le_t) == 1);
#if defined(CONFIG_BT_HCI_HOST) #if defined(CONFIG_BT_HCI_HOST)
/* The Bluetooth subsystem requires that higher priority events shall be given /* The Bluetooth subsystem requires that higher priority events shall be given