After the new firmware upgrade, up to three gas mixes are available
instead of only two. This causes the parsing to fail because there is
now an extra 6 byte gasmix block in the header.
Unfortunately, we can't rely on the firmware version to detect whether
this extra gasmix is present or not. In theory the dive computer can
contain dives in both the old and the new format. Because the firmware
version is a property of the device, and not stored inside each dive,
using the firmware version would either cause the old or the new dives
to fail parsing. This appears to be the approach DM4 is using.
According to some sources on the internet, the logbook gets erased
during the firmware update. However, according to the memory dumps I
received, that appears to be incorrect. The old dives are still
present, and it seems it's only DM4 that fails to download them.
So we need an alternative solution. After a detailed analysis of all
the Suunto dives at my disposal, I noticed something interesting. The
first 5 bytes of each dive are almost static. There are only 5
different variations:
0061906216
0061A06216
0062909118
0062C07118
0063C07118
The interpretation of these bytes is currently unknown, but the second
byte might be some kind of data format version. Each model always has
the same value here, and for the D6i it changes after the firmware
update:
0x61: D4, D6, D9, Cobra 2, Cobra3, Vyper 2, Vyper Air
0x62: D4i, D6i (old firmware), D9tx, HelO2
0x63: D6i (new firmware)
This can't be coincidence, so we use this byte to detect the presence
of the extra gasmix.
The HelO2, D4i, D6i and D9tx all use the same data format for the gas
mixes. The only difference is the number of gas mixes and the initial
byte offset. With this knowledge, we can easily use the same code for
all models. An additional advantage is that because the profile
configuration data is stored immediately after the gasmix section, we
can also replace the hardcoded offset with a simple calculation.
This macro was used to compensate for the fact that the 4 bytes at the
start of each dive, containing the previous and next dive pointers, are
stripped. With the SKIP macro the byte offset remained the same as in
the documentation. Nowadays, this compatibility isn't necessary anymore
and it only makes interpreting the raw binary data more difficult.
The second gas change event (type 0x06) contains both the oxygen and
helium percentages. These are now reported correctly with the new
GASCHANGE2 event.
The D9 family has begin and end of the deco event and we can therefore
convert this to the deco sample. For compatibility with existing software
we keep the events around.
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>
When the gas model setting is set to air, the individual gas mix
definitions retain their previous (non-air) values. This is convenient
to avoid having to adjust the gas mixes again on your next nitrox or
mixed gas dive. But the consequence is that for air dives, the gas model
should take precedence over the individual gas mix definitions, and a
single mix with air is returned instead.
I forgot to update the device and parser initialization functions to
store the context pointer into the objects. As a result, the internal
context pointers were always NULL.
The public api is changed to require a context object for all
operations. Because other library objects store the context pointer
internally, only the constructor functions need an explicit context
object as a parameter.
Adding the "dc_" namespace prefix (which is of course an abbreviation
for libdivecomputer) should avoid conflicts with other libraries. For
the time being, only the high-level device and parser layers are
changed.
The public header files are moved to a new subdirectory, to separate
the definition of the public interface from the actual implementation.
Using an identical directory layout as the final installation has the
advantage that the example code can be build outside the project tree
without any modifications to the #include statements.
The sample configuration data describes which sample data is available
and how it is stored. Using this data should be more reliable than using
a hardcoded configuration.
