[GRASS-dev] GRASS 7: Rast__allocate_null_bits() and Rast__null_bitstream_size()?

GRASS GIS GRASS GIS developer
1

Hi,

in GRASS 7, I found that
  Rast__allocate_null_bits()
  Rast__null_bitstream_size()
are used in r.null and r.support.

Question: why Rast__xxx() and not Rast_xxx()?

Markus

2

Markus Neteler wrote:

in GRASS 7, I found that
  Rast__allocate_null_bits()
  Rast__null_bitstream_size()
are used in r.null and r.support.

Question: why Rast__xxx() and not Rast_xxx()?

That's the convention for functions which are meant for internal use
only.

The only code which needs to use those functions is code which reads
or writes the null bitmap file directly. The "public" interface to the
null bitmap (e.g. Rast_get_null_value_row()) expands the bitmap to one
byte per cell.

Arguably, lib/raster needs e.g. Rast_create_null_bitmap() so that
r.null and r.support don't need to access the file directory.

OTOH, 7.0 is a good opportunity to eliminate the null bitmap
altogether.

--
Glynn Clements <glynn@gclements.plus.com>