1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
|
//! GDT Entry Type
pub const Entry = packed struct {
limit_low: u16,
base_low: u16,
base_middle: u8,
access: u8,
limit_high_and_flags: u8,
base_high: u8,
pub fn init(base: u32, limit: u20, access_byte: u8, flags_nibble: u4) Entry {
return Entry{
.limit_low = @truncate(limit),
.base_low = @truncate(base),
.base_middle = @truncate(base >> 16),
.access = access_byte,
.limit_high_and_flags = @as(u8, flags_nibble) << 4 | @as(u8, @truncate(limit >> 16)),
.base_high = @truncate(base >> 24),
};
}
pub fn null_entry() Entry {
return Entry{
.limit_low = 0,
.base_low = 0,
.base_middle = 0,
.access = 0,
.limit_high_and_flags = 0,
.base_high = 0,
};
}
pub fn get_base(self: Entry) u32 {
return @as(u32, self.base_high) << 24 |
@as(u32, self.base_middle) << 16 |
@as(u32, self.base_low);
}
pub fn get_limit(self: Entry) u20 {
return @as(u20, @truncate(self.limit_high_and_flags & 0x0F)) << 16 |
@as(u20, self.limit_low);
}
pub fn get_flags(self: Entry) u4 {
return @truncate(self.limit_high_and_flags >> 4);
}
pub fn is_present(self: Entry) bool {
return (self.access & 0x80) != 0;
}
pub fn get_dpl(self: Entry) u2 {
return @truncate((self.access >> 5) & 0x03);
}
};
|
