[GRASS5] Making GRASS cross-compiler friendly (was: Script to build babyGRASS for handhelds)

[Frank Warmerdam]

Carl Worth wrote:
> 2) The build process tries to compile, then execute nad2bin. I
>    understand that this is an attempt to create binary files with the
>    correct endian-ness, but it breaks cross-compilation.
> 
>    Workaround: I just compiled nad2bin natively, then continued the
>    build. I think I'm OK, (eg. lucky), here since x86 and arm are the
>    same endian-ness. However, now an unusable nad2bin is being
>    installed with GRASS. Is GRASS going to execute this program during
>    normal operation?
> 
>    Proposal: If GRASS does not execute nad2bin at runtime, then we
>    just need to come up with a mechanism for two different compilers
>    for native cs. cross-compilation. Then, nad2bin could be installed
>    using the native compiler, while all other compilation would use
>    the cross compiler.
> 
>    On the other hand, if GRASS does execute nad2bin during runtime,
>    could we perhaps postpone the compile-time nad2bin calls until
>    run-time? This might be awkward, but it would at least enable
>    cross-compilation.

Carl,

I don't think nad2bin is executed at runtime by GRASS, but it can be
important that the nad2bin that is executed be one that matches the
architecture that will be using the output binary files.  Note that this
isn't just an endian issue, the produced binary files will also be useless
if structure packing is different on the different architectures.

I personally think that PROJ.4 ought to work towards a new architecture
independent format for the grid shift files.  This really wouldn't be hard.
or significantly impair performance.

Best regards,

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