disallow multiple video contexts at compile time

examples/bitmap3.rs

@@ -12,9 +12,9 @@ struct Vector2D {
 
 #[start]
 fn main(_argc: isize, _argv: *const *const u8) -> isize {
-    let gba = gba::Gba::new();
-    let bitmap = gba.display.bitmap3();
-    let vblank = gba.display.get_vblank();
+    let mut gba = gba::Gba::new();
+    let mut bitmap = gba.display.video.bitmap3();
+    let vblank = gba.display.vblank.get();
 
     let mut input = gba::input::ButtonController::new();
     let mut pos = Vector2D {

examples/bitmap4.rs

@@ -7,9 +7,9 @@ use gba::display;
 
 #[start]
 fn main(_argc: isize, _argv: *const *const u8) -> isize {
-    let gba = gba::Gba::new();
-    let bitmap = gba.display.bitmap4();
-    let vblank = gba.display.get_vblank();
+    let mut gba = gba::Gba::new();
+    let mut bitmap = gba.display.video.bitmap4();
+    let vblank = gba.display.vblank.get();
 
     bitmap.set_palette_entry(1, 0x001F);
     bitmap.set_palette_entry(2, 0x03E0);

examples/multiple_video.rs

@@ -0,0 +1,87 @@
+#![no_std]
+#![feature(start)]
+
+extern crate gba;
+
+use gba::display;
+
+struct Vector2D {
+    x: i32,
+    y: i32,
+}
+
+#[start]
+fn main(_argc: isize, _argv: *const *const u8) -> isize {
+    let mut gba = gba::Gba::new();
+    let mut vblank = gba.display.vblank.get();
+    let mut input = gba::input::ButtonController::new();
+
+    loop {
+        bitmap3_mode(&mut gba.display.video.bitmap3(), &mut vblank, &mut input);
+        bitmap4_mode(&mut gba.display.video.bitmap4(), &mut vblank, &mut input);
+    }
+}
+
+fn bitmap3_mode(
+    bitmap: &mut display::bitmap3::Bitmap3,
+    vblank: &mut display::VBlank,
+    input: &mut gba::input::ButtonController,
+) {
+    let mut pos = Vector2D {
+        x: display::WIDTH / 2,
+        y: display::HEIGHT / 2,
+    };
+
+    loop {
+        vblank.wait_for_VBlank();
+
+        input.update();
+        if input.is_just_pressed(gba::input::Button::B) {
+            break;
+        }
+
+        pos.x += input.x_tri() as i32;
+        pos.y += input.y_tri() as i32;
+
+        pos.x = pos.x.clamp(0, display::WIDTH - 1);
+        pos.y = pos.y.clamp(0, display::HEIGHT - 1);
+        bitmap.draw_point(pos.x, pos.y, 0x001F);
+    }
+}
+
+fn bitmap4_mode(
+    bitmap: &mut display::bitmap4::Bitmap4,
+    vblank: &mut display::VBlank,
+    input: &mut gba::input::ButtonController,
+) {
+    bitmap.set_palette_entry(1, 0x001F);
+    bitmap.set_palette_entry(2, 0x03E0);
+
+    bitmap.draw_point_page(
+        display::WIDTH / 2,
+        display::HEIGHT / 2,
+        1,
+        display::bitmap4::Page::Front,
+    );
+    bitmap.draw_point_page(
+        display::WIDTH / 2 + 5,
+        display::HEIGHT / 2,
+        2,
+        display::bitmap4::Page::Back,
+    );
+
+    let mut count = 0;
+    loop {
+        vblank.wait_for_VBlank();
+
+        input.update();
+        if input.is_just_pressed(gba::input::Button::B) {
+            break;
+        }
+
+        count += 1;
+        if count % 6 == 0 {
+            bitmap.flip_page();
+        }
+    }
+}

examples/panic.rs

@@ -7,9 +7,9 @@ use gba::display;
 
 #[start]
 fn main(_argc: isize, _argv: *const *const u8) -> isize {
-    let gba = gba::Gba::new();
-    let bitmap = gba.display.bitmap3();
+    let mut gba = gba::Gba::new();
 
+    let mut bitmap = gba.display.bitmap3();
     let mut input = gba::input::ButtonController::new();
 
     loop {
@@ -18,9 +18,5 @@ fn main(_argc: isize, _argv: *const *const u8) -> isize {
         if input.is_just_pressed(gba::input::Button::A) {
             bitmap.draw_point(display::WIDTH, 0, 0x05);
         }
-        // if B is pressed, try take another bitmap
-        if input.is_just_pressed(gba::input::Button::B) {
-            gba.display.bitmap4();
-        }
     }
 }

src/display/bitmap3.rs

@@ -1,4 +1,4 @@
-use crate::{memory_mapped::MemoryMapped2DArray, single::SingleToken};
+use crate::memory_mapped::MemoryMapped2DArray;
 
 use super::{
     set_graphics_mode, set_graphics_settings, DisplayMode, GraphicsSettings, HEIGHT, WIDTH,
@@ -9,20 +9,18 @@ use core::convert::TryInto;
 const BITMAP_MODE_3: MemoryMapped2DArray<u16, { WIDTH as usize }, { HEIGHT as usize }> =
     unsafe { MemoryMapped2DArray::new(0x600_0000) };
 
-pub struct Bitmap3<'a> {
-    _in_mode: SingleToken<'a>,
-}
+pub struct Bitmap3 {}
 
-impl<'a> Bitmap3<'a> {
-    pub(crate) unsafe fn new(in_mode: SingleToken<'a>) -> Self {
+impl Bitmap3 {
+    pub(crate) unsafe fn new() -> Self {
         set_graphics_mode(DisplayMode::Bitmap3);
         set_graphics_settings(GraphicsSettings::LAYER_BG2);
-        Bitmap3 { _in_mode: in_mode }
+        Bitmap3 {}
     }
 
     /// Draws point to screen at (x, y) coordinates with colour and panics if
     /// (x, y) is out of the bounds of the screen.
-    pub fn draw_point(&self, x: i32, y: i32, colour: u16) {
+    pub fn draw_point(&mut self, x: i32, y: i32, colour: u16) {
         let x = x.try_into().unwrap();
         let y = y.try_into().unwrap();
         BITMAP_MODE_3.set(x, y, colour)

src/display/bitmap4.rs

@@ -1,7 +1,4 @@
-use crate::{
-    memory_mapped::{MemoryMapped1DArray, MemoryMapped2DArray},
-    single::SingleToken,
-};
+use crate::memory_mapped::{MemoryMapped1DArray, MemoryMapped2DArray};
 
 use super::{
     set_graphics_mode, set_graphics_settings, DisplayMode, GraphicsSettings, DISPLAY_CONTROL,
@@ -26,21 +23,19 @@ pub enum Page {
     Back = 1,
 }
 
-pub struct Bitmap4<'a> {
-    _in_mode: SingleToken<'a>,
-}
+pub struct Bitmap4 {}
 
-impl<'a> Bitmap4<'a> {
-    pub(crate) unsafe fn new(in_mode: SingleToken<'a>) -> Self {
+impl Bitmap4 {
+    pub(crate) unsafe fn new() -> Self {
         set_graphics_mode(DisplayMode::Bitmap4);
         set_graphics_settings(GraphicsSettings::LAYER_BG2);
-        Bitmap4 { _in_mode: in_mode }
+        Bitmap4 {}
     }
 
     /// Draws point on specified page at (x, y) coordinates with colour index
     /// whose colour is specified in the background palette. Panics if (x, y) is
     /// out of the bounds of the screen.
-    pub fn draw_point_page(&self, x: i32, y: i32, colour: u8, page: Page) {
+    pub fn draw_point_page(&mut self, x: i32, y: i32, colour: u8, page: Page) {
         let addr = match page {
             Page::Front => BITMAP_PAGE_FRONT_MODE_4,
             Page::Back => BITMAP_PAGE_BACK_MODE_4,
@@ -60,7 +55,7 @@ impl<'a> Bitmap4<'a> {
     /// Draws point on the non-current page at (x, y) coordinates with colour
     /// index whose colour is specified in the background palette. Panics if (x,
     /// y) is out of the bounds of the screen.
-    pub fn draw_point(&self, x: i32, y: i32, colour: u8) {
+    pub fn draw_point(&mut self, x: i32, y: i32, colour: u8) {
         let disp = DISPLAY_CONTROL.get();
 
         // get other page
@@ -74,13 +69,13 @@ impl<'a> Bitmap4<'a> {
     }
 
     /// Sets the colour of colour index in the background palette.
-    pub fn set_palette_entry(&self, entry: u32, colour: u16) {
+    pub fn set_palette_entry(&mut self, entry: u32, colour: u16) {
         PALETTE_BACKGROUND.set(entry as usize, colour);
     }
 
     /// Flips page, changing the Gameboy advance to draw the contents of the
     /// other page
-    pub fn flip_page(&self) {
+    pub fn flip_page(&mut self) {
         let disp = DISPLAY_CONTROL.get();
         let swapped = disp ^ GraphicsSettings::PAGE_SELECT.bits();
         DISPLAY_CONTROL.set(swapped);

src/display/mod.rs

@@ -9,6 +9,7 @@ use bitmap4::Bitmap4;
 
 pub mod bitmap3;
 pub mod bitmap4;
+pub mod tiled0;
 
 const DISPLAY_CONTROL: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x0400_0000) };
 const DISPLAY_STATUS: MemoryMapped<u16> = unsafe { MemoryMapped::new(0x0400_0004) };
@@ -45,50 +46,42 @@ enum DisplayMode {
     Bitmap5 = 5,
 }
 
+#[non_exhaustive]
 /// Manages distribution of display modes, obtained from the gba struct
 pub struct Display {
-    in_mode: Single,
-    vblank: Single,
+    pub video: Video,
+    pub vblank: VBlankGiver,
+}
+#[non_exhaustive]
+pub struct Video {}
+
+#[non_exhaustive]
+pub struct VBlankGiver {}
+
+impl Video {
+    /// Bitmap mode that provides a 16-bit colour framebuffer
+    pub fn bitmap3(&mut self) -> Bitmap3 {
+        unsafe { Bitmap3::new() }
+    }
+
+    /// Bitmap 4 provides two 8-bit paletted framebuffers with page switching
+    pub fn bitmap4(&mut self) -> Bitmap4 {
+        unsafe { bitmap4::Bitmap4::new() }
+    }
+}
+
+impl VBlankGiver {
+    /// Gets a vblank handle where only one can be obtained at a time
+    pub fn get(&mut self) -> VBlank {
+        unsafe { VBlank::new() }
+    }
 }
 
 impl Display {
     pub(crate) const unsafe fn new() -> Self {
         Display {
-            in_mode: Single::new(),
-            vblank: Single::new(),
-        }
-    }
-
-    /// Bitmap mode that provides a 16-bit colour framebuffer
-    pub fn bitmap3(&self) -> Bitmap3 {
-        unsafe {
-            Bitmap3::new(
-                self.in_mode
-                    .take()
-                    .expect("Cannot create new mode as mode already taken"),
-            )
-        }
-    }
-
-    /// Bitmap 4 provides two 8-bit paletted framebuffers with page switching
-    pub fn bitmap4(&self) -> Bitmap4 {
-        unsafe {
-            bitmap4::Bitmap4::new(
-                self.in_mode
-                    .take()
-                    .expect("Cannot create new mode as mode already taken"),
-            )
-        }
-    }
-
-    /// Gets a vblank handle where only one can be obtained at a time
-    pub fn get_vblank(&self) -> VBlank {
-        unsafe {
-            VBlank::new(
-                self.vblank
-                    .take()
-                    .expect("Cannot create another vblank handler"),
-            )
+            video: Video {},
+            vblank: VBlankGiver {},
         }
     }
 }
@@ -121,16 +114,14 @@ pub fn busy_wait_for_VBlank() {
 
 /// Once obtained, this guarentees that interrupts are enabled and set up to
 /// allow for waiting for vblank
-pub struct VBlank<'a> {
-    _got: SingleToken<'a>,
-}
+pub struct VBlank {}
 
-impl<'a> VBlank<'a> {
-    unsafe fn new(a: SingleToken<'a>) -> Self {
+impl VBlank {
+    unsafe fn new() -> Self {
         crate::interrupt::enable_interrupts();
         crate::interrupt::enable(crate::interrupt::Interrupt::VBlank);
         enable_VBlank_interrupt();
-        VBlank { _got: a }
+        VBlank {}
     }
 
     #[allow(non_snake_case)]
@@ -141,7 +132,7 @@ impl<'a> VBlank<'a> {
     }
 }
 
-impl<'a> Drop for VBlank<'a> {
+impl Drop for VBlank {
     fn drop(&mut self) {
         unsafe {
             disable_VBlank_interrupt();

src/single.rs

@@ -1,5 +1,3 @@
-use core::cell::Cell;
-
 pub struct Singleton<T> {
     single: Option<T>,
 }
@@ -15,27 +13,25 @@ impl<T> Singleton<T> {
 }
 
 pub struct Single {
-    is_taken: Cell<bool>,
+    is_taken: bool,
 }
 
 pub struct SingleToken<'a> {
-    cell: &'a Cell<bool>,
+    cell: &'a mut bool,
 }
 
 impl Single {
     pub const fn new() -> Self {
-        Single {
-            is_taken: Cell::new(false),
-        }
+        Single { is_taken: false }
     }
 
-    pub fn take(&self) -> Result<SingleToken, &'static str> {
-        if self.is_taken.get() {
+    pub fn take(&mut self) -> Result<SingleToken, &'static str> {
+        if self.is_taken {
             Err("Already taken")
         } else {
-            self.is_taken.set(true);
+            self.is_taken = true;
             Ok(SingleToken {
-                cell: &self.is_taken,
+                cell: &mut self.is_taken,
             })
         }
     }
@@ -43,6 +39,6 @@ impl Single {
 
 impl Drop for SingleToken<'_> {
     fn drop(&mut self) {
-        self.cell.set(false);
+        (*self.cell) = false;
     }
 }