Uwatec Smart Z data download takes 1.5 hours for only 4 dives

[Jef Driesen]

On 23-12-13 22:37, Jef Driesen wrote:
> On 23-12-13 22:25, Dirk Hohndel wrote:
>> On Mon, 2013-12-23 at 22:21 +0100, Jef Driesen wrote:
>>> Unfortunately that's a limitation of how subsurface implements the "download
>>> only new dives" feature. Subsurface starts downloading dives, and aborts the
>>> download once a previously downloaded dive is recognized. But the Uwatec
>>> protocol forces you to always download ALL dives at once, unless you tell it not
>>> to do that. This works by sending a device timestamp to the device during
>>> handshaking, and then the device will only return those dives that are more
>>> recent than the timestamp (e.g. only the new dives). This is available in
>>> libdivecomputer through the fingerprint feature, but subsurface doesn't use it.
>>>
>>> @Dirk: This is one of those cases where a custom "download only new dives"
>>> implementation will always be less efficient than libdivecomputer's built-in
>>> fingerprint based implementation.
>>
>> Linus - I don't remember why we did not use the fingerprint based
>> implementation... can you remind me?
>
> The import change here is that you'll need to maintain a small "database" to
> store the most recent fingerprints, one for each unique device (based on the
> family type and serial number). The fingerprints can be stored in the xml, or
> somewhere separately as you wish.
>
> There is an example implementation in the universal app. With the "-c" option
> you can specify a directory where the fingerprint database (just one file per
> unique device) is stored. Everything else happens automatically. There is also
> the "-f" option to try a specific fingerprint. That last one is often handy for
> trying the feature manually.

See this post for some more detailed info:

http://lists.hohndel.org/pipermail/subsurface/2012-November/001685.html

Jef