mirror of
https://github.com/italicsjenga/agb.git
synced 2024-12-23 16:21:33 +11:00
Make missing a vblank interrupt wait less painful (#374)
If you missed a vblank, then the next call to wait_for_vblank would pointlessly wait rather than returning immediately. Meaning if you missed a vblank by a few cycles, you'd be waiting for the entire next one :(. - [x] Changelog updated / no changelog update needed
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commit
7525a6f572
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@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
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### Changed
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- Text renderer can now be re-used which is useful for rpg style character/word at a time text boxes.
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- If a vblank happens outside of `wait_for_vblank`, then next call will immediately return.
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### Fixed
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- Zero volume now plays no sound.
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@ -7,7 +7,7 @@ use core::{
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use alloc::boxed::Box;
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use bare_metal::CriticalSection;
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use crate::{display::DISPLAY_STATUS, memory_mapped::MemoryMapped};
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use crate::{display::DISPLAY_STATUS, memory_mapped::MemoryMapped, sync::Static};
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#[derive(Clone, Copy)]
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pub enum Interrupt {
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@ -308,27 +308,43 @@ where
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r
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}
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static NUM_VBLANKS: Static<usize> = Static::new(0); // overflows after 2.27 years
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static HAS_CREATED_INTERRUPT: Static<bool> = Static::new(false);
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#[non_exhaustive]
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pub struct VBlank {}
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pub struct VBlank {
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last_waited_number: Cell<usize>,
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}
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impl VBlank {
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/// Handles setting up everything required to be able to use the wait for
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/// interrupt syscall.
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#[must_use]
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pub fn get() -> Self {
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interrupt_to_root(Interrupt::VBlank).add();
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VBlank {}
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if !HAS_CREATED_INTERRUPT.read() {
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let handler = add_interrupt_handler(Interrupt::VBlank, |_| {
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NUM_VBLANKS.write(NUM_VBLANKS.read() + 1);
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});
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core::mem::forget(handler);
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HAS_CREATED_INTERRUPT.write(true);
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}
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VBlank {
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last_waited_number: Cell::new(NUM_VBLANKS.read()),
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}
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}
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/// Pauses CPU until vblank interrupt is triggered where code execution is
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/// resumed.
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pub fn wait_for_vblank(&self) {
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crate::syscall::wait_for_vblank();
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}
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}
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let last_waited_number = self.last_waited_number.get();
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self.last_waited_number.set(NUM_VBLANKS.read() + 1);
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impl Drop for VBlank {
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fn drop(&mut self) {
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interrupt_to_root(Interrupt::VBlank).reduce();
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if last_waited_number < NUM_VBLANKS.read() {
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return;
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}
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crate::syscall::wait_for_vblank();
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}
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}
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@ -339,10 +355,13 @@ mod tests {
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use core::cell::RefCell;
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#[test_case]
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fn test_vblank_interrupt_handler(_gba: &mut crate::Gba) {
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{
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let counter = Mutex::new(RefCell::new(0));
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fn test_can_create_and_destroy_interrupt_handlers(_gba: &mut crate::Gba) {
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let mut counter = Mutex::new(RefCell::new(0));
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let counter_2 = Mutex::new(RefCell::new(0));
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let vblank = VBlank::get();
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{
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let _a = add_interrupt_handler(Interrupt::VBlank, |key: CriticalSection| {
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*counter.borrow(key).borrow_mut() += 1;
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});
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@ -350,8 +369,6 @@ mod tests {
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*counter_2.borrow(key).borrow_mut() += 1;
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});
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let vblank = VBlank::get();
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while free(|key| {
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*counter.borrow(key).borrow() < 100 || *counter_2.borrow(key).borrow() < 100
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}) {
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@ -359,11 +376,10 @@ mod tests {
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}
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}
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assert_eq!(
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interrupt_to_root(Interrupt::VBlank).next.get(),
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core::ptr::null(),
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"expected the interrupt table for vblank to be empty"
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);
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vblank.wait_for_vblank();
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vblank.wait_for_vblank();
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assert_eq!(*counter.get_mut().get_mut(), 100);
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}
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#[test_case]
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@ -56,7 +56,7 @@ pub fn wait_for_interrupt() {
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/// The vblank interrupt handler [VBlank][crate::interrupt::VBlank] should be
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/// used instead of calling this function directly.
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pub fn wait_for_vblank() {
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pub(crate) fn wait_for_vblank() {
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unsafe {
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asm!(
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"swi {SWI}",
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