device_tree/
util.rs

1pub use core::{convert, fmt, option, result, str};
2
3#[inline]
4pub fn align(val: usize, to: usize) -> usize {
5    val + (to - (val % to)) % to
6}
7
8#[derive(Debug)]
9pub enum SliceReadError {
10    UnexpectedEndOfInput,
11}
12
13pub type SliceReadResult<T> = Result<T, SliceReadError>;
14
15pub trait SliceRead {
16    fn read_be_u32(&self, pos: usize) -> SliceReadResult<u32>;
17    fn read_be_u64(&self, pos: usize) -> SliceReadResult<u64>;
18    fn read_bstring0(&self, pos: usize) -> SliceReadResult<&[u8]>;
19    fn subslice(&self, start: usize, len: usize) -> SliceReadResult<&[u8]>;
20}
21
22impl<'a> SliceRead for &'a [u8] {
23    fn read_be_u32(&self, pos: usize) -> SliceReadResult<u32> {
24        // check size is valid
25        if ! (pos+4 <= self.len()) {
26            return Err(SliceReadError::UnexpectedEndOfInput)
27        }
28
29        Ok(
30            (self[pos] as u32) << 24
31            | (self[pos+1] as u32) << 16
32            | (self[pos+2] as u32) << 8
33            | (self[pos+3] as u32)
34        )
35    }
36
37    fn read_be_u64(&self, pos: usize) -> SliceReadResult<u64> {
38        // check size is valid
39        if ! (pos+8 <= self.len()) {
40            return Err(SliceReadError::UnexpectedEndOfInput)
41        }
42
43        Ok(
44            (self[pos] as u64) << 56
45            | (self[pos+1] as u64) << 48
46            | (self[pos+2] as u64) << 40
47            | (self[pos+3] as u64) << 32
48            | (self[pos+4] as u64) << 24
49            | (self[pos+5] as u64) << 16
50            | (self[pos+6] as u64) << 8
51            | (self[pos+7] as u64)
52        )
53    }
54
55    fn read_bstring0(&self, pos: usize) -> SliceReadResult<&[u8]> {
56        let mut cur = pos;
57        while cur < self.len() {
58            if self[cur] == 0 {
59                return Ok(&self[pos..cur])
60            }
61
62            cur += 1;
63        }
64
65        Err(SliceReadError::UnexpectedEndOfInput)
66    }
67
68    fn subslice(&self, start: usize, end: usize) -> SliceReadResult<&[u8]> {
69        if ! (end < self.len()) {
70            return Err(SliceReadError::UnexpectedEndOfInput)
71        }
72
73        Ok(&self[start..end])
74    }
75}
device_tree/util.rs

device_tree/
util.rs
