Split out bump_allocator

This commit is contained in:
Gwilym Kuiper 2021-08-16 21:14:28 +01:00
parent 8a0cb86eda
commit 94d5a71007
2 changed files with 88 additions and 85 deletions

View file

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

View file

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