Being able to synchronize the dive computer clock with the host system
is a very useful feature. Add the infrastructure to support this feature
through the public api.
On Windows, the hidapi library uses the standard Microsoft USB HID
driver, while libusb requires the installation of a different driver
(WinUSB or libusbK). But installing one of the libusb drivers breaks
compatibility with other applications using hidapi (Scubapro LogTRAK and
Suunto DM5) because only one driver can be active. Switching
libdivecomputer to hidapi avoids this problem.
On Linux, the hidapi library doesn't seem to offer any advantages over
libusb. Most distributions don't even have the hidapi library installed
by default. Because there are usually two variants of the hidapi library
available on Linux (hidapi-libusb and hidapi-hidraw), the autotools
build system won't be able to detect it out-of-the-box, and will
automatically fallback to the libusb implementation.
On Mac OS X, hidapi is already the default (and also the only option).
The Windows HID api always expects to receive a fixed size buffer
(corresponding to the largest report supported by the device). Therefore
the hidapi library internally pads the buffer with zeros to the expected
size, but apparently it also returns the size of the padded buffer! As a
workaround the number of bytes is limited to the actual size.
The hidapi read and write functions return a negative value if an error
occurs. Those negative values should not be returned to the caller as
the actual number of bytes (or used in the logging). The value is reset
to zero instead.
The zero report ID byte is required when using the hidapi library. We
just never noticed this problem before, because we use libusb by
default, and libusb doesn't need the extra zero byte.
The hidapi library requires that the first byte contains the report ID.
For devices which support only a single report, the report ID byte
should be zero. The remaining bytes contain the actual report data.
Now, when hidapi uses libusb internally, it strips the zero report ID
byte again before passing the data to libusb. Thus in order to remain
compatible with the hidapi based implementation, our libusb based
implementation should do the same.
The correct name for the OSTC 3+ is OSTC Plus nowadays. Allthough the
exact name doesn't really matter because all OSTC3 based models are
compatible, using the correct name should reduce confusing for
end-users.
I received a bug report from a device which failed to download new dives
after a reset (probably caused by an empty battery). This reset appears
to reset the internal dive counter back to zero, and also resets the
write pointer back to the begin of the logbook ringbuffer, but leaves
the existing logbook entries in place. The result is that the logic to
find the most recent dive based on the highest internal dive counter,
will be wrong because it finds those old entries.
The discovery of the logbook (and profile) write pointers eliminates the
need to search for the most recent logbook entry.
I dived the model enough to wrap the profile buffer and I was wrong
about where the end was. Also, the buffer starts 3 bytes after where it
could. We were treating profile pointers as 4 bytes when they are two
bytes. This worked most of the time when short tissues were clear
(tissue load follows the pointer).
The Cochran Commander TM appears to be a first generation Commander with
limited storage and function compared to later models.
The main differences are:
- The TM doesn't support high-speed transfer so use the 0x05 read
command and don't change to a higher baud rate. Still reset to 9600
to wait for the heartbeat.
- The TM has a different config command (one byte).
- The TM has only one config page.
For previously supported Cochran computers high-speed read of log and
profile data started at byte 0. Older models that lack the high-speed
transfer function use the standard speed read commands and so the log
and profile data are read at higher addresses.
Since moving to per-dive download of profile data (and now rbstream
download) the data->sample_data_offset and data->sample_size variables
aren't used so calculating them doesn't make sense.
The progress bar was taking 18 seconds between updates on a Commander II
when using a 128K pagesize. Since devices differ in their baud rates, it
makes sense to use smaller pages on slower devices. This change reduces
it to 32K on a Commander II and to 64K on EMC devices.
Newer cochran DCs record a gas change event at the begining of a
dive. The code creates a gas change before processing samples so
with newer DCs this resulted in duplicate events.
The method used to calculate the data used by dives (to determine when
we run out of ringbuffer) incorrectly didn't include surface sample
data. Ten to twenty minute of sample data is recorded at the surface in
case the diver re-descends, continuing the dive. The code then thought
that older dive profiles were not yet overwritten. The improper data was
returned to the user.
This function is much more useful if it works like a
ringbuffer_distance() function. It assumed the wrong values when
calculating profile size and it didn't have easy access to values it
needed to properly calculate profile sizes.
It makes sense to keep since it validates pointers.
Commander II pointers to profile ringbuffer data was wrong. After seeing
the Commander I encoding I realized the Commander II encoding of RB
pointers was in a flipped word big endian format. It only appeared to be
in normal big endian format because of an adjacent pointer that usually
shared the same first two bytes.
This adds support for older Cochran Commander dive computers,
specifically Commanders with serial numbers prior to 21000.
This also renames "Commander" model to "Commander II" and
adds "Commander I" to refer to pre-21000 models.
Since commit 344bfab229a17c7227b9bec02f616505a8d9e998 only a subset of
the id string is used to detect the model. But because the offset was
never updated, the model detection always fails now.
At the moment, the progress reporting will jump straight from about 0%
at the start of the download to 100% at the end of the download, without
any updates in between. This is improved by updating after every packet.
The error code returned by the dc_usbhid_read() function should be
returned as-is, instead of being replaced with some generic error, which
gets translated again to DC_STATUS_IO in the caller.
I did the packet logging for the received data side, but forgot to do
the same thing on the command transfer side, which makes the debug logs
a bit less useful.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When doing the G2 downloader, I dropped the initial handshake as I tried
to keep the code minimal, and the handshake didn't seem to make any
difference what-so-ever to me.
And it probably doesn't matter for anybody else either. But the code
isn't working for some people, and maybe it does actually matter.
More importantly, Scubapro's own LogTRAK application does send those two
initial commands, and it's probably a good idea to minimize the
differences between the different downloaders anyway, so add the
handshake sequence back in.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
