Add support for Mares Sirius #65
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What are the changeset id(s) that you cherry-picked from https://github.com/libdivecomputer/libdivecomputer for this? |
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@mikeller To be exact it's not a cherry pick anymore (as if git cherry pick), I just took code from libdivecomputer to make it work, because first time I did it I couldn't build Subsurface on my M1 Mac. I made another attempt. I'm not familiar with C, so it was a bit of a struggle to fix merge issues, so I opted to pick manually what I needed. Relevant commits from libdivecomputer libdivecomputer/libdivecomputer@4516842...8fe598e |
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@rmultan: Unfortunately not having the original commits cleanly cherry-picked and the additional changes in a separate commit will create merge conflicts for all future merges from the libdivecomputer upstream. So merging this in its current form is not a good option. |
Devices supporting BLE 4.2 (or higher) can use data packets with a payload size of up to 244 bytes. None of the current Mares models support this at the moment, but increasing the size on the receiving side already prepares the code for future models and remains fully backwards compatible. Signed-off-by: rmultan <[email protected]>
The macros make the code a bit more compact, and adding support for new models becomes easier too. Signed-off-by: rmultan <[email protected]>
The Mares Genius (and compatible models) uses a new command to download different types of objects, instead of manually reading and parsing the flash memory. This command also supports reading device properties like the serial number. This change is necessary because newer models like the Sirius no longer support reading directly from the flash memory. Signed-off-by: rmultan <[email protected]>
The current implementation assumes a fixed order for the different record types to share some code with the older models. See commits [1] and [2] for more details. The main disadvantages of this approach are the extra complexity and the limited flexibility to adapt to future changes to the data format. To make the parsing code more future proof, split the code into separate functions for the Genius/Horizon and the older models. [1] Commit 8b06f2c (Horizon) [2] Commit feec939 (Genius) Signed-off-by: rmultan <[email protected]>
The Mares Sirius uses the same communication protocol as the Genius, except for the fact that it uses a newer BLE version which supports larger data packets. The actual MTU is likely negotiated because we see different sizes like 244 and 182 bytes. We don't have access to this MTU size because not all BLE implementations can expose this information. Unfortunately not only the BLE packet size is variable, but also the size of the higher level data frames (used for downloading the content of the objects) is no longer fixed. The frame size appears to adapt to the BLE MTU size. This is most likely done to reduce the overhead and maximize the throughput. Although each frame ends with an OxEA byte, we can't rely on this knowledge to detect the end of the frame. The END byte is not escaped in the payload, and thus can also appear anywhere in the frame. As a workaround, we rely on the fact that each frame appears to be send as a single BLE packet. The only exception is the ACK byte, which gets send as a separate BLE packet if the command requires parameter data. Compatible models: Quad Ci, Puck 4 and Puck Air 2 Signed-off-by: rmultan <[email protected]>
Signed-off-by: rmultan <[email protected]>
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@mikeller Updated with an actual cherry pick. If it works for you I'm happy to update the version in the main repository as well, if not I'll just wait for your merge of the upstream. |
Cherry pick changes from libdivecomputer to
allow support for Mares Sirius computer.