/bitfield/trunk

BitField,

manage bit fields in vala without going insane.

(c) Gustav Hartvigsson 2020

Main Reposetory:

https://launchpad.net/bitfield

CONCEPT:

The basic concept of a bitfield is to provide some kind of siple storrage of

information, that should not take too much space.

The basic way of doing this is using something like uint8 or uint16,

which provides us with up to 8 and 16 fields respectivly, with the simplest

field being 1 bit, up to the one-field type having the full 8bit (256 value)

or 16bit (65535 values) to work with in one field.

When defining a bitfiled type you need to consider what fields you need, how

many values each feald sholud have and how they corrolate to your data.

lets take the examlpe of a simple game map, where you have information like

if a tile is travelsable or if only cetain types of units can move over them.

If we have land units and water units, we could represet that with as little as

2 bits:

 * 00 - Not traverable,

 * 01 - travelable by land units,

 * 10 - travelable by sea units.

 * 11 - traverable by both types of units.

That means that we have 14 bits left if we use a 16 bit value, or 6 bits left

if we use an 8 bit value.

For the sake of argument, we are going to be using an 8 bit value in the

example below.

  Tile [0][0][0][0][0][0][0][0]

        ^--^  ^--^  ^--------^

        trav  Tile     Tile

              Set      Texture

Legend:

 * Trav         - What sort of traversal is posible on the tile.

 * Tile Set     - You four tile sets, you cound switch between them here.

 * Tile Texture - The specific tile texture in the tile set you want to have

                  on this tile.

Since each tile on the map is only one 8 bit value, instead of multi byte

data structures, you will save on memory.

The nivé solution would be to use a struct or each tile and have the information

stored in seral bytes and store that in an array, but that would take up 3 times

as much space, or more if you use other types.

struct foo {

  uint8 traversable;

  uint8 tile_set;

  uint8 texture;

}

USAGE:

For basic usage see the example in main.vala.

C HowTo:

int main (int argc, char * argv[]) {

  // TODO

}