base/alloc/
paging.rs

1pub static mut ALLOC_START: usize = 0;
2pub const PAGE_SIZE: usize = 1 << PAGE_ORDER;
3pub const PAGE_ORDER: usize = 12;
4
5/// Represent (repr) our entry bits as
6/// unsigned 64-bit integers.
7#[repr(usize)]
8#[derive(Copy, Clone)]
9pub enum EntryBits {
10   None = 0,
11   Valid = 1 << 0,
12   Read = 1 << 1,
13   Write = 1 << 2,
14   Execute = 1 << 3,
15   User = 1 << 4,
16   Global = 1 << 5,
17   Access = 1 << 6,
18   Dirty = 1 << 7,
19
20   // Convenience combinations
21   ReadWrite = 1 << 1 | 1 << 2,
22   ReadExecute = 1 << 1 | 1 << 3,
23   ReadWriteExecute = 1 << 1 | 1 << 2 | 1 << 3,
24
25   // User Convenience Combinations
26   UserReadWrite = 1 << 1 | 1 << 2 | 1 << 4,
27   UserReadExecute = 1 << 1 | 1 << 3 | 1 << 4,
28   UserReadWriteExecute = 1 << 1 | 1 << 2 | 1 << 3 | 1 << 4,
29}
30
31impl EntryBits {
32   pub fn value(self) -> usize {
33      return self as usize;
34   }
35}
36
37#[derive(Clone, Copy, Debug)]
38pub struct Entry {
39   pub entry: usize,
40}
41
42impl Entry {
43   pub fn valid(&self) -> bool {
44      return self.entry & EntryBits::Valid.value() != 0;
45   }
46
47   // The first bit (bit index #0) is the V bit for
48   // valid.
49   pub fn invalid(&self) -> bool {
50      return !self.valid();
51   }
52
53   // A leaf has one or more RWX bits set
54   pub fn leaf(&self) -> bool {
55      return self.entry & 0xe != 0;
56   }
57
58   pub fn branch(&self) -> bool {
59      return !self.leaf();
60   }
61
62   pub fn set_entry(&mut self, entry: usize) {
63      self.entry = entry;
64   }
65}
66
67#[derive(Clone, Copy, Debug)]
68pub struct Table {
69   pub entries: [Entry; 512],
70}
71
72impl Table {
73   pub fn length() -> usize {
74      return 512;
75   }
76}
77
78// BUDDY ALLOCATOR //
79
80// BEST-FIT ALLOCATOR //
81// TODO: implement best-fit allocator.
82
83// IMPORTS //
base/alloc/paging.rs

base/alloc/
paging.rs
