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[mkgmap-dev] [PATCH v1] Display of the IMG header

From WanMil wmgcnfg at web.de on Mon Feb 14 19:17:46 GMT 2011

>> On 12/02/11 15:32, WanMil wrote:
>>> I observed that the MapSource search menu is disabled if the MDR file is
>>> larger than 0x7FFFFFF (134217727) bytes.
>>> Maybe in this case a flag must be set?
>> My guess is in ImgHeader:
>> // This sectors, head, cylinders stuff appears to be used by mapsource
>> // and they have to be larger than the actual size of the map.  It
>> // doesn't appear to have any effect on a garmin device or other software.
>> int sectors = 0x20;   // 0x20 appears to be a max
>> header.putShort(OFF_SECTORS, (short) sectors);
>> int heads = 0x20;     // 0x20 appears to be max
>> header.putShort(OFF_HEADS, (short) heads);
>> int cylinders = 0x100;   // gives 128M will try more later
>> Try boosting cylinders to 0x200, or try to find if there is a maximum
>> useful value like it appears that there is for the others.
>> ..Steve
> My first simple tries were not successful. MapSource reject the maps
> with changed cylinder values.
> So I have started to implement the display for the IMG file header to be
> able to analyze it. There are many solutions possible:
> * Wrong E2 value? My large MDR-IMG files use E2=3. This seems to be too low.
> * There are still quite a number of unknown bytes. Some of them are set
> in my official Garmin maps.
> WanMil

Hopefully the patch helps to find the correct settings for larger IMG files.

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