Crate rubidium

GBA Memory-mapped IO (MMIO) stuff.

The GBA is controlled via MMIO. An MMIO location is called a “register”, similar to the CPU having registers. The different registers are all globally accessible, so user code must have its own convention for who is supposed to touch what values when.

This crate defines newtypes that describe the data layout of each register, and if you enable the unsafe_addresses feature it also defines the addresses of each register. The type of address used for each register lets you know about the safety (or not) of accessing a given register. The safety assessment relies on the code being run only on a GBA, so if you use this crate on your desktop or something that’s your fault.

This is only “work in progress” status, but please file an issue if things are unclear. While you’re waiting you can also check GBATEK, which is the standard resource for GBA info (and it’s most of where this crate’s docs come from).

Naming Conventions

By default, the name used for an address is the same as the GBATEK name.

In some cases I’ve combined what GBATEK considers multiple adjacent registers into a single larger register. For example, WININ and WINOUT have been combined to simply be exposed as WIN_CONTROL. The MMIO is flexible like this, as long as the alignment of the combined address is correct for the combined data type it’s all fine. Let me know what you think (tracker), because we could make adjustments in this area.

For each setting within a register data newtype there will be three methods per setting contained within the newtype:

• A const “getter” named the same as the setting (eg: foo).
• A const “with-er” which takes self and returns a new value (eg: with_foo).
• A “setter” which takes &mut self and updates the value in place (eg: set_foo). This will hopefully also be const in a future version of Rust.

Structs

• AlphaBlendValue
  Coefficients for the alpha blending special effect.
• BackgroundControlValue
  Lets you adjust how each background layer is displayed.
• BlendControlValue
  This lets you configure hardware color blending.
• Color
  On the GBA, colors have 5 bits per channel.
• ColorSpecialEffect
  The color special effects available via hardware on the GBA.
• DangerWriteVolAddr
  Represents an MMIO address that can be safely read, but writes are dangerous.
• DisplayControlValue
  Top level control for the LCD display.
• DisplayStatusValue
  Relates to the status of the display.
• HighActiveKeys
  The GBA’s key data, where a high value in a bit means the key is pressed.
• LowActiveKeys
  The GBA’s key data, where a low value in a bit means the key is pressed.
• Mode3
  A ZST for namespacing VideoMode3 stuff into one place.
• Mode4
  A ZST for namespacing VideoMode4 stuff into one place.
• Mode5
  A ZST for namespacing VideoMode4 stuff into one place.
• Mode3Col
  A particular column within the Mode 3 bitmap.
• Mode3Row
  A particular row within the Mode 3 bitmap.
• Mode4Col
  A column within one of the two Mode 4 indexmaps.
• Mode4Frame
  One of the two indexmap frames available in Mode 4.
• Mode4Row
  A row within one of the two Mode 4 indexmaps.
• Mode5Col
  A column of one of the two Mode 5 bitmaps.
• Mode5Frame
  One of the two bitmap frames available in Mode 5.
• Mode5Row
  A row within one of the Mode 5 frames.
• MosaicControlValue
  Controls the intensity of the “mosaic” special effect.
• PALRAM
  A ZST for namespacing palette ram related functionality.
• ReadOnlyVolAddr
  Represents an MMIO address that can be safely read, but not written.
• SimpleVolAddr
  Represents a simple MMIO address that can be safely read or written.
• VideoMode
  The video modes available on the GBA.
• WinHorizontal
  Defines the horizontal bounds of Window 0 and 1.
• WinVertical
  Defines the vertical bounds of Window 0 and 1.
• WindowControlValue
  Lets you set what layers appear inside and outside of the window areas.
• WriteOnlyVolAddr
  Represents a simple MMIO address that can be written but not read.

Constants

• BG0CNT
  “Background 0 Control” (Text mode only).
• BG0OFS
  “Background 0 Offset” (Text mode only).
• BG1CNT
  “Background 1 Control” (Text mode only).
• BG1OFS
  “Background 1 Offset” (Text mode only).
• BG2CNT
  “Background 2 Control” (Text/Affine mode only).
• BG2OFS
  “Background 0 Offset” (Text mode only).
• BG2_AFFINE_MATRIX
  “Background 2 Affine Parameter Matrix” (Affine/Bitmap mode only).
• BG2_REF_POINT
  “Background 2 Reference Point” (Affine/Bitmap mode only).
• BG3CNT
  “Background 3 Control” (Text/Affine mode only).
• BG3OFS
  “Background 0 Offset” (Text mode only).
• BG3_AFFINE_MATRIX
  “Background 3 Affine Parameter Matrix” (Affine mode only).
• BG3_REF_POINT
  “Background 3 Reference Point” (Affine mode only).
• BLDALPHA
  “Alpha Blend Control”.
• BLDBRIGHT
  “Brightness Blend Control”.
• BLDCNT
  “Blend Control”.
• DISPCNT
  “Display Control”
• DISPSTAT
  “Display Status”
• KEYINPUT
  The register that lets you read the current state of all the keys.
• MOSAIC
  “Mosaic Effect”
• VCOUNT
  “Vertical Counter”
• VRAM
  Base address value of VRAM.
• WIN_CONTROL
  “Window Controls”
• WIN_HORIZONTAL
  “Window Horizontal Edges”
• WIN_VERTICAL
  “Window Vertical Edges”