The new APOS4 firmware changed the data format and communication
protocol. The size of the samples changed from 54 to 64 bytes, and in
order to speedup the download, a single data packet contains 3 samples
at once. If the number of samples is not an exact multiple of three, the
last packet appears to contain garbage data.
For parsing, the firmware version is available in the dive header.
Unfortunately it can't be used for dives that are downloaded from a
device with the new firmware, but which have been recorded with an older
firmware. Such dives store the old firmware version in the dive header,
but they also use the new sample format. As a workaround, we inspect the
size of the dive.
The second variant of the open or create functions were introduced to
maintain backwards compatibility. But after being removed from the
public api, these functions serve no purpose anymore, and can be removed
completely.
The vendor_product_parser_create() and vendor_product_device_open()
functions should be called indirectly, through the generic
dc_device_open() and dc_parser_new() functions. And the
vendor_product_extract_dives() functions are internal functions that
should never have been part of the public api in the first place.
The low level serial and IrDA functions are modified to:
- Use the libdivecomputer namespace prefix.
- Return a more detailed status code instead of the zero on success and
negative on error return value. This will allow to return more
fine-grained error codes.
- The read and write functions have an additional output parameter to
return the actual number of bytes transferred. Since these functions
are not atomic, some data might still be transferred successfully if
an error occurs.
The dive computer backends are updated to use the new api.
Both the allocation and initialization of the object data structure is
now moved to a single function. The corresponding deallocation function
is intended to free objects that have been allocated, but are not fully
initialized yet. The public cleanup function shouldn't be used in such
case, because it may try to release resources that haven't been
initialized yet.
Instead of freeing the object data structure in the backend specific
cleanup function, the memory is now freed automatically in the base
class function. This reduces the amount of boilerplate code in the
backends. Backends that don't allocate any additional resources, do no
longer require a cleanup function at all.
When the close function returns, all resources should be freed,
regardless of whether an error has occured or not. The error code is
purely informative.
However, in order to return the first error code, which is usually the
most interesting one, the current implementation is unnecessary
complicated. If an error occurs, there is no need to exit immediately.
Simply store the error code unless there is already a previous one, and
then continue.
The protocol of the iX3M series is almost identical to the protocol of
the iDive series. The main difference is that the command bytes and the
size of the response packets have been changed. In order to be able to
communicate with the correct set of commands, the user needs to supply
the correct number now. To maintain backwards compatibility, a new
variant of the open function is added.
The size of the dive header is one byte smaller: 0x32 instead of 0x33
bytes. Because we were expecting a larger packet, this bug caused the
downloading of the dive headers to fail. I'm surprised no one noticed
this mistake before.
