aligned bytes, Closes: https://github.com/rust-console/gba/issues/79

CHANGELOG.md

@@ -3,6 +3,8 @@
 * **0.9.1:**
   * Adds some randomization support directly into the crate.
   * Added more methods to the `Fixed` type.
+  * Adds an `include_aligned_bytes!` macro to pull in compile time data that's
+    aligned to 4.
 * **0.9.0:**
   * **MSRV:** The crate now requires `compiler_builtins-0.1.81` to build. You
     will need a Nightly from 2022-10-15 or later.

examples/foo.txt

@@ -0,0 +1 @@
+foo_

examples/hello.rs

@@ -2,10 +2,7 @@
 #![no_main]
 
 use core::fmt::Write;
-use gba::{
-  mgba::{MgbaBufferedLogger, MgbaMessageLevel},
-  prelude::*,
-};
+use gba::prelude::*;
 
 #[panic_handler]
 fn panic_handler(info: &core::panic::PanicInfo) -> ! {
@@ -15,6 +12,9 @@ fn panic_handler(info: &core::panic::PanicInfo) -> ! {
   loop {}
 }
 
+#[allow(dead_code)]
+const FOO_: Align4<[u8; 4]> = include_aligned_bytes!("foo.txt");
+
 #[link_section = ".ewram"]
 static FRAME_KEYS: GbaCell<KeyInput> = GbaCell::new(KeyInput::new());
 

src/lib.rs

@@ -101,3 +101,24 @@ pub mod random;
 pub mod sound;
 pub mod timers;
 pub mod video;
+
+/// Wraps a value to be aligned to a minimum of 4.
+///
+/// If the size of the value held is already a multiple of 4 then this will be
+/// the same size as the wrapped value. Otherwise the compiler will add
+/// sufficient padding bytes on the end to make the size a multiple of 4.
+#[repr(C, align(4))]
+pub struct Align4<T>(pub T);
+
+/// As [`include_bytes!`] but the value is wrapped in [`Align4`]
+///
+/// ## Panics
+/// * The included number of bytes must be a multiple of 4.
+#[macro_export]
+macro_rules! include_aligned_bytes {
+  ($file:expr $(,)?) => {{
+    let LONG_NAME_THAT_DOES_NOT_CLASH = *include_bytes!($file);
+    assert!(LONG_NAME_THAT_DOES_NOT_CLASH.len() % 4 == 0);
+    Align4(LONG_NAME_THAT_DOES_NOT_CLASH)
+  }};
+}

src/prelude.rs

@@ -2,5 +2,6 @@
 
 pub use crate::{
   asm_runtime::*, bios::*, builtin_art::*, dma::*, fixed::*, gba_cell::*,
-  interrupts::*, keys::*, mmio::*, sound::*, timers::*, video::*,
+  include_aligned_bytes, interrupts::*, keys::*, mgba::*, mmio::*, sound::*,
+  timers::*, video::*, Align4,
 };

src/random.rs

@@ -124,6 +124,7 @@ pub trait Gen32 {
 }
 
 impl Gen32 for Lcg32 {
+  #[inline]
   fn next_u32(&mut self) -> u32 {
     Lcg32::next_u32(self)
   }