[GRASS-dev] i.atcorr and static array: conditionalize for 64bit?

[Markus GRASS]

Markus Neteler wrote:
> (this was before on GRASS-user)
>
> On Sat, May 16, 2009 at 6:51 PM, Markus Neteler <neteler at osgeo.org> wrote:
> ...
>   
>>> main.cpp:181: error: size of array ‘tic’ is too large
>>>       
>> the problem is fixed: the recently increased cache did not fit
>> on 32bit CPUs but only on 64bit. Now it is reduced to
>> 4096 and it compiles again on 32bit, too.
>>
>> TODO: implement dynamically allocated arrays in the cache.
>>     
>
> Since this is unlikely to happen in the near future unless we
> find a volunteer - is there a possibility to simply add a condition:
>
> if 32bit CPU, then use 4096,
> if 64bit CPU, then use 2^16 *2 = 131072 (the largest value which
>    I found to not segfault i.atcorr)
>
> We speak about time reduction from several weeks to 40 minutes.
>   
That seems to apply to class TICache and class TIMap. Both the TIMap and
the TICache are (very often?) searched by simply going through the
arrays. These searches, if they are really performed very often during
execution of the module, would be much much faster using a balanced
binary search tree instead of an array, added bonus would be to get rid
of the limitation posed by MAX_TIs and MAX_TICs because TIMap and
TICache  would no longer be arrays but just pointers to the root of the
respective search tree. IMHO, a further time reduction from 40 minutes
to something like 4 minutes is not impossible. Any cpp guru out there
willing to test this idea?

Markus M