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[mkgmap-dev] Improved street search in index branch

From Steve Ratcliffe steve at parabola.me.uk on Wed Jan 19 15:18:45 GMT 2011


> I had some looks at the code, especially on MDRSection7, which is
> important for street search. And, yes, there are some more fields
> decoded. But most of the comments are in polish, so it's very hard (at
> least for me) to unterstand what those fields are used for and where to
> get the required data.

There are other possible fields but they are not necessarily essential
as mapsource adds some of these fields when it downloads to a device,
so they do not need to be present in the index to begin with.

As far as I understand it, one of these fields is a flag to say that
there is more than one word in the name of the street (or perhaps a

Another field is used for an alternative kind of index where every
word in the street name is indexed separately.  So if you had a name:

	Yellow Grass Lane

it would be sorted under 'Y' as normal, but also under 'G'.  The entry
that was under 'G' would have this field set to the position of the
character 'G' in the name - so 8 in this case (or 7 if it starts at 0
- whatever).

While this would be useful, we need to get the basic index working first.

It would be good to know exactly what is required to get things
working on the device, since the index has very many possible
sections and we don't have enough people working on it to implement

My next guess would be mdr 20, 21, 22 as these are referred to in the
reverse index which is used by mapsource to determine what is
downloaded to the device.  They are lists of pointers into the street
names ordered in particular ways (city, region etc) and so very
relevant to the problem areas.


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