68 lines
1.9 KiB
Rust
68 lines
1.9 KiB
Rust
use core::{
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ops::{Deref, DerefMut},
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mem::{align_of, size_of},
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};
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use alloc::alloc::{dealloc, Layout, LayoutError};
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use crate::mmu::{L1_PAGE_SIZE, L1Table};
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pub struct UncachedSlice<T: 'static> {
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layout: Layout,
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slice: &'static mut [T],
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}
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impl<T> UncachedSlice<T> {
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/// allocates in chunks of 1 MB
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pub fn new<F: Fn() -> T>(len: usize, default: F) -> Result<Self, LayoutError> {
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// round to full pages
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let size = ((len * size_of::<T>() - 1) | (L1_PAGE_SIZE - 1)) + 1;
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let align = align_of::<T>()
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.max(L1_PAGE_SIZE);
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let layout = Layout::from_size_align(size, align)?;
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let ptr = unsafe { alloc::alloc::alloc(layout).cast::<T>() };
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let start = ptr as usize;
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assert_eq!(start & (L1_PAGE_SIZE - 1), 0);
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for page_start in (start..(start + size)).step_by(L1_PAGE_SIZE) {
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// non-shareable device
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L1Table::get()
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.update(page_start as *const (), |l1_section| {
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l1_section.tex = 0b10;
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l1_section.cacheable = true;
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l1_section.bufferable = false;
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});
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}
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let slice = unsafe { core::slice::from_raw_parts_mut(ptr, len) };
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// verify size
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assert!(unsafe { slice.get_unchecked(len) } as *const _ as usize <= start + size);
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// initialize
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for e in slice.iter_mut() {
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*e = default();
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}
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Ok(UncachedSlice { layout, slice })
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}
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}
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/// Does not yet mark the pages cachable again
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impl<T> Drop for UncachedSlice<T> {
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fn drop(&mut self) {
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unsafe {
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dealloc(self.slice.as_mut_ptr() as *mut _ as *mut u8, self.layout);
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}
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}
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}
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impl<T> Deref for UncachedSlice<T> {
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type Target = [T];
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fn deref(&self) -> &Self::Target {
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self.slice
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}
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}
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impl<T> DerefMut for UncachedSlice<T> {
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fn deref_mut(&mut self) -> &mut Self::Target {
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self.slice
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}
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}
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