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Split out bump_allocator
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86
agb/src/agb_alloc/bump_allocator.rs
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86
agb/src/agb_alloc/bump_allocator.rs
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@ -0,0 +1,86 @@
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use core::alloc::{GlobalAlloc, Layout};
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use crate::interrupt::Mutex;
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fn get_data_end() -> usize {
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extern "C" {
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static __ewram_data_end: usize;
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}
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// TODO: This seems completely wrong, but without the &, rust generates
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// a double dereference :/. Maybe a bug in nightly?
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(unsafe { &__ewram_data_end }) as *const _ as usize
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}
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pub(super) struct BumpAllocator {
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current_ptr: Mutex<*mut u8>,
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}
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impl BumpAllocator {
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pub const fn new() -> Self {
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Self {
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current_ptr: Mutex::new(core::ptr::null_mut()),
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}
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}
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}
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impl BumpAllocator {
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fn alloc_safe(&self, layout: Layout) -> *mut u8 {
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let mut current_ptr = self.current_ptr.lock();
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let ptr = if current_ptr.is_null() {
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get_data_end()
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} else {
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*current_ptr as usize
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};
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let alignment_bitmask = layout.align() - 1;
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let fixup = ptr & alignment_bitmask;
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let amount_to_add = layout.align() - fixup;
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let resulting_ptr = ptr + amount_to_add;
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*current_ptr = (resulting_ptr + layout.size()) as *mut _;
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resulting_ptr as *mut _
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}
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}
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unsafe impl GlobalAlloc for BumpAllocator {
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unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
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self.alloc_safe(layout)
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}
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unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {}
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}
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#[alloc_error_handler]
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fn alloc_error(layout: Layout) -> ! {
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panic!(
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"Failed to allocate size {} with alignment {}",
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layout.size(),
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layout.align()
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);
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}
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#[cfg(test)]
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mod test {
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use alloc::boxed::Box;
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#[test_case]
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fn test_box(_gba: &mut crate::Gba) {
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let first_box = Box::new(1);
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let second_box = Box::new(2);
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assert!(&*first_box as *const _ < &*second_box as *const _);
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assert_eq!(*first_box, 1);
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assert_eq!(*second_box, 2);
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let address = &*first_box as *const _ as usize;
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assert!(
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address >= 0x0200_0000 && address < 0x0204_0000,
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"ewram is located between 0x0200_0000 and 0x0204_0000, address was actually found to be {:#010X}",
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address
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);
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}
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}
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@ -1,89 +1,6 @@
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use core::alloc::{GlobalAlloc, Layout};
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mod bump_allocator;
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use super::interrupt::Mutex;
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fn get_data_end() -> usize {
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extern "C" {
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static __ewram_data_end: usize;
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}
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// TODO: This seems completely wrong, but without the &, rust generates
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// a double dereference :/. Maybe a bug in nightly?
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(unsafe { &__ewram_data_end }) as *const _ as usize
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}
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struct BumpAllocator {
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current_ptr: Mutex<*mut u8>,
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}
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impl BumpAllocator {
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pub const fn new() -> Self {
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Self {
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current_ptr: Mutex::new(core::ptr::null_mut()),
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}
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}
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}
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impl BumpAllocator {
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fn alloc_safe(&self, layout: Layout) -> *mut u8 {
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let mut current_ptr = self.current_ptr.lock();
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let ptr = if current_ptr.is_null() {
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get_data_end()
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} else {
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*current_ptr as usize
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};
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let alignment_bitmask = layout.align() - 1;
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let fixup = ptr & alignment_bitmask;
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let amount_to_add = layout.align() - fixup;
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let resulting_ptr = ptr + amount_to_add;
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*current_ptr = (resulting_ptr + layout.size()) as *mut _;
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resulting_ptr as *mut _
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}
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}
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unsafe impl GlobalAlloc for BumpAllocator {
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unsafe fn alloc(&self, layout: Layout) -> *mut u8 {
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self.alloc_safe(layout)
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}
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unsafe fn dealloc(&self, _ptr: *mut u8, _layout: Layout) {}
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}
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#[alloc_error_handler]
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fn alloc_error(layout: Layout) -> ! {
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panic!(
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"Failed to allocate size {} with alignment {}",
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layout.size(),
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layout.align()
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);
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}
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use bump_allocator::BumpAllocator;
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#[global_allocator]
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static GLOBAL_ALLOC: BumpAllocator = BumpAllocator::new();
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#[cfg(test)]
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mod test {
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use alloc::boxed::Box;
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#[test_case]
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fn test_box(_gba: &mut crate::Gba) {
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let first_box = Box::new(1);
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let second_box = Box::new(2);
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assert!(&*first_box as *const _ < &*second_box as *const _);
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assert_eq!(*first_box, 1);
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assert_eq!(*second_box, 2);
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let address = &*first_box as *const _ as usize;
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assert!(
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address >= 0x0200_0000 && address < 0x0204_0000,
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"ewram is located between 0x0200_0000 and 0x0204_0000, address was actually found to be {:#010X}",
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address
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);
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}
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}
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