[GRASS5] Raster lib and CELL files > 2GB

[Glynn Clements]

Markus Neteler wrote:

> for a remote sensing project we face the problem to arrive
> at file sizes > 2GB. I see two options:
> 
> a) change the CELL file compression from RLE to DEFLATE 
>   -> how to do that? I just want to change locally for me

That's far from simple. The existing low-level raster I/O
implementation is a total mess; learning how it works may well take
longer than re-writing it from scratch.

Compare read_data_fp_compressed() with read_data_compressed() in
get_row.c, and put_data() with put_fp_data() in put_row.c.

> b) enable large file support (http://www.suse.de/~aj/linux_lfs.html)
>   -> any functions which need a change?

Search for all occurrences of "long" in libgis, then figure out which
ones need to be changed to off_t. AFAICT, most of them are likely to
be in the following files:

	G.h (row_ptr field)
	closecell.c
	format.c
	get_row.c
	opencell.c
	put_row.c

> Variant a) sounds somewhat better to me and maybe already solves
> the problem.
> 
> Recommendations are welcome.

c) obtain a system where "long" is 64 bits.

-- 
Glynn Clements <glynn.clements at virgin.net>