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This adds ability for read and write operations to work with messages aligned to configured number of bytes. This has few different use cases. The alignment is specified as unsigned integer and can be changed with ioctl command CANIOC_SET_MSGALIGN. The current value can be queried by CANIOC_GET_MSGALIGN command. The default value for the message alignment is 1. This will provide behavior consistent with current one. Thus messages are placed to the buffer right after data of the previous one. The same applies for writes. The special alignment value 0 disables read and write of multiple frames. Thus read will always return at most one message and write will always write only one message even if larger buffer size is provided. Another use case is if message alignment is set to exactly message representation size (`sizeof(struct can_msg_s)`). This allows writing and reading arrays of messages. Other values provide even more advanced and specialized use cases, such as optimizations if architecture has to emulate some non-aligned accesses, there alignment of for example 4 bytes could provide performance boost. The original motivation behind this is was compatibility with socket CAN. It is easier to port applications to NuttX's CAN driver if only one frame is provided at the time. This solution was suggested by Pavel Pisa <pisa@fel.cvut.cz> as a more versatile variant of plain boolean disabling the multiple frame retrieval. Signed-off-by: Karel Kočí <kkoci@elektroline.cz>
Apache NuttX is a real-time operating system (RTOS) with an emphasis on standards compliance and small footprint. Scalable from 8-bit to 64-bit microcontroller environments, the primary governing standards in NuttX are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs (such as VxWorks) are adopted for functionality not available under these standards, or for functionality that is not appropriate for deeply-embedded environments (such as fork()).
For brevity, many parts of the documentation will refer to Apache NuttX as simply NuttX.
Getting Started
First time on NuttX? Read the Getting Started guide! If you don't have a board available, NuttX has its own simulator that you can run on terminal.
Documentation
You can find the current NuttX documentation on the Documentation Page.
Alternatively, you can build the documentation yourself by following the Documentation Build Instructions.
The old NuttX documentation is still available in the Apache wiki.
Supported Boards
NuttX supports a wide variety of platforms. See the full list on the Supported Platforms page.
Contributing
If you wish to contribute to the NuttX project, read the Contributing guidelines for information on Git usage, coding standard, workflow and the NuttX principles.
License
The code in this repository is under either the Apache 2 license, or a license compatible with the Apache 2 license. See the License Page for more information.