Re: Efficiently setting up large quantities of constant data

[Andre <avsaway@hotmail.com>]

Dr. Adrian Wrigley wrote:
> A similar question I have is how to link in regular files and access
> their contents in Ada.
> 
> For example, suppose I have a binary file "distances.dat" containing
> the (road) distances between 1000 different cities.  This could be a 2MB
> file computed by another application. How can I build a single executable
> file containing the data and access it from the Ada code?
> 
> I presume this needs to be done at the linker stage, but I don't
> see any options to link in non-object files.  The obvious alternative
> of distributing the data files separately and reading them in
> is slower and much less tidy than having a single self-contained binary.
> 
> (I tried Google, but probably didn't use the right search terms...)

If you are writting for the Windows platform you have two options:

1. Put it in a resource file and use a resource compiler to add it to 
your executable. With WIN32 the functions Find_Resource and 
Lock_Resource you can get a pointer to the data.

2. Use a memory mapped file. This way you also get a pointer to the data 
and Windows is taking care of loading it into the memory. Data reading 
using a memory mapped file is just as fast as putting it in the executable.

Andr�