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
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
use crate::{DtbObj, Path, Property, Reg, RegCfg, StructureBlock as Blk, WalkOperation};
use core::slice;
/// 设备树递归结构。
pub(crate) struct Walker<'a> {
pub tail: &'a [Blk],
pub strings: &'a [u8],
}
impl Walker<'_> {
/// 切分属性名。
fn prop_name(&self, nameoff: Blk) -> &[u8] {
let nameoff = nameoff.into_u32() as usize;
let name = &self.strings[nameoff..];
&name[..name.iter().position(|c| *c == b'\0').unwrap()]
}
/// 深度优先遍历。如果返回 `false`，取消所有后续的遍历。
pub fn walk_inner(
&mut self,
f: &mut impl FnMut(&Path<'_>, DtbObj) -> WalkOperation,
path: &Path<'_>,
reg_cfg: RegCfg,
mut escape: bool,
) -> bool {
use WalkOperation::*;
let mut sub_reg_cfg = RegCfg::DEFAULT;
loop {
match self.tail.split_first() {
// 子节点
Some((&Blk::NODE_BEGIN, tail)) => {
// 找到字符串结尾
let name_len = tail.iter().position(Blk::is_end_of_str).unwrap() + 1;
let (name, tail) = tail.split_at(name_len);
self.tail = tail;
if escape {
// 如果当前子树已选跳过，不可能再选择终止
assert!(self.walk_inner(f, path, sub_reg_cfg, true));
} else {
// 正确舍弃尾 '\0'
let name = unsafe {
slice::from_raw_parts(
name.as_ptr().cast::<u8>(),
name.len() * Blk::LEN - name.last().unwrap().str_tail_zero(),
)
};
let escape = match f(path, DtbObj::SubNode { name }) {
StepInto => false,
StepOver => true,
StepOut => {
escape = true;
true
}
Terminate => return false,
};
if !self.walk_inner(
f,
&Path {
parent: Some(path),
name,
},
sub_reg_cfg,
escape,
) {
return false;
}
}
}
// 当前节点结束
Some((&Blk::NODE_END, tail)) => {
self.tail = tail;
return true;
}
// 属性
Some((&Blk::PROP, [len, nameoff, tail @ ..])) => {
// 切分属性值
let len = len.into_u32() as usize;
let (value, tail) = tail.split_at((len + Blk::LEN - 1) / Blk::LEN);
// 如果当前子树需要解析
if !escape {
let op = match self.prop_name(*nameoff) {
b"#address-cells" if value.len() == 1 => {
sub_reg_cfg.address_cells = value[0].into_u32();
StepOver
}
b"#size-cells" if value.len() == 1 => {
sub_reg_cfg.size_cells = value[0].into_u32();
StepOver
}
b"reg" if value.len() % reg_cfg.item_size() == 0 => f(
path,
DtbObj::Property(Property::Reg(Reg {
buf: value,
cfg: reg_cfg,
})),
),
name => f(path, DtbObj::Property(Property::new(name, value, len))),
};
match op {
StepInto | StepOver => {}
StepOut => escape = true,
Terminate => return false,
};
}
self.tail = tail;
}
// 跳过
Some((&Blk::NOP, tail)) => self.tail = tail,
Some((_, _)) | None => unreachable!(),
}
}
}
}