bit struct types

[Lokathor]

We need to somehow support structs where each bit controls a thing.

Example using the LCD Control:

0) BG & Window Enable / Priority
1) OBJ Enable
2) OBJ Large Size
3) BG Tilemap Higher
4) BG & Window Tiles Higher
5) Window Enabled
6) Window Tile Map Area Higher
7) LCD Enabled

Each bit controls one thing.

We need a syntax that lets the user make values of these types for loading into a register

a = // how to write the literal?
LCDC = a

and also a syntax that lets the user check or edit a value

a = LCDC
// how to check a particular bit?

Ideally users would be able to define their own types as well, but that's probably a longer term goal.

[Lokathor]

Current top idea:

// general form for accessing the `lcd_enabled` bit of the `LcdControl` type in the `a` register.
a.LcdControl.lcd_enabled

// assign `a` the value of `LcdControl` with `lcd_enabled` set (and no other bits set)
a = LcdControl { lcd_enabled }

// set or clear a specific bit
a.LcdControl.lcd_enabled = true
a.LcdControl.lcd_enabled = false

// branch on the bit being set
if a.LcdControl.lcd_enabled {
  foo()
}

// branch on the bit being clear
if not a.LcdControl.lcd_enabled {
  bar()
}