osiris/mem/pfa/
bitset.rs

1use core::pin::Pin;
2use core::ptr::NonNull;
3
4use hal::mem::PhysAddr;
5
6use crate::{
7    error::Result,
8    types::{
9        bitset::BitAlloc,
10        boxed::{self, Box},
11    },
12};
13
14pub struct Allocator<const N: usize> {
15    begin: PhysAddr,
16    bitalloc: BitAlloc<N>,
17}
18
19impl<const N: usize> Allocator<N> {
20    pub fn new(begin: PhysAddr) -> Option<Self> {
21        if !begin.is_multiple_of(super::PAGE_SIZE) {
22            return None;
23        }
24
25        if begin > PhysAddr::MAX - (N * super::PAGE_SIZE * usize::BITS as usize) {
26            return None;
27        }
28
29        Some(Self {
30            begin,
31            bitalloc: BitAlloc::new(N * BitAlloc::<N>::BITS_PER_WORD)?,
32        })
33    }
34}
35
36impl<const N: usize> super::Allocator<N> for Allocator<N> {
37    fn initializer() -> unsafe fn(PhysAddr, usize) -> Result<Pin<Box<Self>>> {
38        |addr: PhysAddr, pcnt: usize| -> Result<Pin<Box<Self>>> {
39            if pcnt > N {
40                todo!("Runtime page frame allocator for more than {} pages", N)
41            }
42
43            if !addr.is_multiple_of(core::mem::align_of::<Self>()) {
44                return Err(kerr!(InvalidArgument));
45            }
46
47            let ptr = NonNull::new(addr.as_mut_ptr::<Self>()).ok_or(kerr!(InvalidArgument))?;
48            // Align this up to PAGE_SIZE
49            let begin = addr + size_of::<Self>();
50            let begin = if begin.is_multiple_of(super::PAGE_SIZE) {
51                begin
52            } else {
53                PhysAddr::new((begin.as_usize() + super::PAGE_SIZE - 1) & !(super::PAGE_SIZE - 1))
54            };
55            // TODO: Subtract the needed pages from the available
56            unsafe {
57                core::ptr::write(
58                    ptr.as_ptr(),
59                    Self::new(begin).ok_or(kerr!(InvalidArgument))?,
60                )
61            };
62
63            // Safety: Ptr is properly aligned and non-null. The validity of the memory at that address is valid by the call contract.
64            Ok(Pin::new(unsafe { boxed::Box::from_raw(ptr) }))
65        }
66    }
67
68    fn alloc(&mut self, page_count: usize) -> Option<PhysAddr> {
69        let idx = self.bitalloc.alloc(page_count)?;
70        Some(self.begin + (idx * super::PAGE_SIZE))
71    }
72
73    fn free(&mut self, addr: PhysAddr, page_count: usize) {
74        if !addr.is_multiple_of(super::PAGE_SIZE) {
75            panic!("Address must be page aligned");
76        }
77        let idx = addr.diff(self.begin) / super::PAGE_SIZE;
78        self.bitalloc.free(idx, page_count);
79    }
80}
osiris/mem/pfa/bitset.rs

osiris/mem/pfa/
bitset.rs
