The Scubapro LogTrak application doesn't send the handshake commands for
BLE communication. Also the Aladin Sport Matrix, which supports only
BLE, responds with a 0x01 byte instead of the expected 0x01 byte and
that causes the handshaking to fail. Thus simply omit the handshaking
for BLE communication.
Reported-by: Berthold Stöger <berthold.stoeger@tuwien.ac.at>
The Uwatec Smart, Meridian and G2 backends are almost identical, except
for the low-level packet sending and receiving code. With the new I/O
layer, those three backends can easily be unified in a single backend.
The Meridian and G2 are completely removed, only the family types are
kept for backwards compatibility.
The Aladin Tec (and Tec 2G) sample descriptor table supports up to two
event bytes, but there is only a single event descriptor. This missing
descriptor causes a fatal error during parsing. Add a dummy descriptor
to avoid the error.
Instead of reading data packets, the code is actually sending some
random data to the dive computer! A small typo with bad consequences!
This is a critical bug because it not only causes the download to fail,
but also appears to change random settings on the dive computer. I
suspect that the garbage data that gets send to the dive computer
happens to contain some valid write settings commands.
For most I/O stream implementations the serial communication specific
functions are meaningless. Implementing them as no-ops allows the dive
computer backends the call the I/O stream functions unconditionally.
However, implementing the no-op with a dummy function returning
DC_STATUS_SUCCESS, does not only add some (small) overhead at runtime,
but also requires many such functions. This is inconvenient and the same
result can easily be obtained by using a NULL pointer instead.
The consequence is that the logic is reversed now. To obtain the
previous behaviour of returning the DC_STATUS_UNSUPPORTED error code
again, you'll need to implement a dummy function. But that's fine
because it's the less common case.
I/O functions with output parameters, should always initialize those
output parameters, even when an error is returned. This prevents the
(accidental) use of uninitialized variables, whenever the caller forgets
to check the return code.
As a nice side effect, the use of a local variable guarantees that the
underlying I/O implementation will always receive a valid pointer.
When two or more identical (or very similar) dive computers are
connected, the USB VID/PID can be ambiguous. That's because the VID/PID
identifies the type of the USB device, and not the individual device.
But each USB HID device descriptor returned by the device discovery
represents a single connected device, and thus guarantees to open the
correct USB device.
To obtain the same behaviour as before, an application can simply open
the first discovered device.
Replace the global USB library context with a reference counted session
to manage the lifetime of the USB library context. For the libusb based
implementation, this is actually a much better match for the underlying
libusb api, and allows to eliminate the global state. For the hidapi
based implementation, the global state is unavoidable because the hidapi
doesn't support multiple sessions. Therefore we use a singleton session.
The main difference with the serial communication is that the BLE
communication transmits each SLIP encoded data packet as one or more BLE
data packets. The BLE packets have an extra two byte header with the
total number of packets and the current packet number.
The main difference with the serial communication is that the BLE
communication uses data packets (with a maximum size of 20 bytes)
instead of a continuous data stream.
The main difference with the USB HID communication is that the BLE data
packets have a variable size and are no longer padded to the full 32
(Tx) or 64 (Rx) bytes.
The main difference with the USB HID communication is that the BLE data
stream is encoded using HDLC framing with a 32 bit CRC checksum. Due to
this encoding, the data packets can no longer be processed one by one
(as is done for the USB HID packets). The entire HDLC encoded stream
needs to be received before it can be processed. This requires some
additional buffering.
Setting a default transport type avoids the need to explicitely set a
transport using the the new --transport command-line option. This also
preserves backwards compatibility with previous versions where the
option didn't exist yet.
The dctool example application is updated to the latest changes:
- The I/O stream is opened and closed by the application.
- A new (mandatory) option is added to select the desired transport
type. This is nessecary because several dive computers support
multiple transport types now.
Currently the dive computer backends are responsible for opening (and
closing) the underlying I/O stream internally. The consequence is that
each backend is hardwired to a specific transport type (e.g. serial,
irda or usbhid). In order to remove this dependency and support more
than one transport type in the same backend, the opening (and closing)
of the I/O stream is moved to the application.
The dc_device_open() function is modified to accept a pointer to the I/O
stream, instead of a string with the device node (which only makes sense
for serial communication). The dive computer backends only depend on the
common I/O interface.
With the support for multiple transports per device, the
dc_descriptor_get_transport() function became obsolete because it does
support only a single transport type. Applications should use the new
dc_descriptor_get_transports() function instead.
With the support for multiple transports per device and the possibility
to use custom I/O implementations, libdivecomputer no longer knows which
devices are actually supported. Hence libdivecomputer needs to always
report all the devices it knows about, and it's up to the application to
filter out entries for which there is no suitable transport available
(either built-in or custom).
Because the list of supported built-in transports depends on the
availability of external libraries (libusb, hidapi) and the operating
system, the application needs some mechanism to retrieve this
information at runtime. Therefore, a new dc_context_get_transports()
function is added, which returns a bitmask with all the available
built-in transports.
Several dive computers support multiple transports. For example the
Suunto Eon Steel supports both USB HID and BLE. All devices using
bluetooth classic communication support both the native bluetooth
transport and the legacy serial port emulation.
To support this feature, the values of the dc_transport_t type are
changed into bitmasks, and the dc_descriptor_t struct is extended with a
bitfield with all the supported transports.
Add a function to query the underlying transport type. This allows the
dive computer backends to implement transport specific behaviour where
necessary.
For the built-in I/O implementations, the transport type is obviously
always hardcoded, but for a custom I/O implementation the application
needs to provide the correct type. Hence the transport type can't be
hardcoded in the vtable and needs to be passed as a parameter.
Trying to purge the input buffer by reading and discarding data packets,
results in an annoying and confusing error message if no data packet is
received. To avoid this error, the functionality should be integrated in
the USB HID code, either automatically during initialization or by
implementing the purge function.
But since there seems to be no evidence that this is actually necessary,
let's remove this code.
Check the fingerprint before downloading the dive. If a match is found,
this avoids some unnecessary communication and thus makes the download a
little bit faster.
The file list isn't freed when an error occurs, and the strings returned
from the lookup_enum function are dynamically allocated and thus should
be freed as well.
The descriptor strings are dynamically allocated and owned by the
struct. The const qualifiers are a bit misleading here, and result in
warnings when trying to free the pointers again.
The multiplication is evaluated using 32bit arithmetic, and then stored
in a 64bit integer. The 32bit integer overflow can be avoided by casting
to a 64bit type first.
