1/// A wrapper for the output slice used when decompressing.
2///
3/// Using this rather than `Cursor` lets us implement the writing methods directly on
4/// the buffer and lets us use a usize rather than u64 for the position which helps with
5/// performance on 32-bit systems.
6pub struct OutputBuffer<'a> {
7 slice: &'a mut [u8],
8 position: usize,
9}
10
11impl<'a> OutputBuffer<'a> {
12 #[inline]
13 pub fn from_slice_and_pos(slice: &'a mut [u8], position: usize) -> OutputBuffer<'a> {
14 OutputBuffer { slice, position }
15 }
16
17 #[inline(always)]
18 pub const fn position(&self) -> usize {
19 self.position
20 }
21
22 #[inline(always)]
23 pub fn set_position(&mut self, position: usize) {
24 self.position = position;
25 }
26
27 /// Write a byte to the current position and increment
28 ///
29 /// Assumes that there is space.
30 #[inline]
31 pub fn write_byte(&mut self, byte: u8) {
32 self.slice[self.position] = byte;
33 self.position += 1;
34 }
35
36 /// Write a slice to the current position and increment
37 ///
38 /// Assumes that there is space.
39 #[inline]
40 pub fn write_slice(&mut self, data: &[u8]) {
41 let len = data.len();
42 self.slice[self.position..self.position + len].copy_from_slice(data);
43 self.position += data.len();
44 }
45
46 #[inline]
47 pub const fn bytes_left(&self) -> usize {
48 self.slice.len() - self.position
49 }
50
51 #[inline(always)]
52 pub const fn get_ref(&self) -> &[u8] {
53 self.slice
54 }
55
56 #[inline(always)]
57 pub fn get_mut(&mut self) -> &mut [u8] {
58 self.slice
59 }
60}
61
62/// A wrapper for the output slice used when decompressing.
63///
64/// Using this rather than `Cursor` lets us implement the writing methods directly on
65/// the buffer and lets us use a usize rather than u64 for the position which helps with
66/// performance on 32-bit systems.
67#[derive(Copy, Clone)]
68pub struct InputWrapper<'a> {
69 slice: &'a [u8],
70}
71
72impl<'a> InputWrapper<'a> {
73 #[inline(always)]
74 pub const fn as_slice(&self) -> &[u8] {
75 self.slice
76 }
77
78 #[inline(always)]
79 pub const fn from_slice(slice: &'a [u8]) -> InputWrapper<'a> {
80 InputWrapper { slice }
81 }
82
83 #[inline(always)]
84 pub fn advance(&mut self, steps: usize) {
85 self.slice = &self.slice[steps..];
86 }
87
88 #[inline]
89 pub fn read_byte(&mut self) -> Option<u8> {
90 self.slice.first().map(|n| {
91 self.advance(1);
92 *n
93 })
94 }
95
96 #[inline]
97 #[cfg(target_pointer_width = "64")]
98 pub fn read_u32_le(&mut self) -> u32 {
99 let ret = {
100 let four_bytes: [u8; 4] = self.slice[..4].try_into().unwrap_or_default();
101 u32::from_le_bytes(four_bytes)
102 };
103 self.advance(4);
104 ret
105 }
106
107 #[inline(always)]
108 pub const fn bytes_left(&self) -> usize {
109 self.slice.len()
110 }
111}
112