ppmd_rust/
decoder_8.rs

1use std::io::Read;
2
3use crate::{
4    internal::ppmd8::{Ppmd8, RangeDecoder},
5    Error, RestoreMethod, PPMD8_MAX_MEM_SIZE, PPMD8_MAX_ORDER, PPMD8_MIN_MEM_SIZE, PPMD8_MIN_ORDER,
6    SYM_END,
7};
8
9/// A decoder to decompress data using PPMd8 (PPMdI rev.1).
10pub struct Ppmd8Decoder<R: Read> {
11    ppmd: Ppmd8<RangeDecoder<R>>,
12    finished: bool,
13}
14
15impl<R: Read> Ppmd8Decoder<R> {
16    /// Creates a new [`Ppmd8Decoder`] which provides a reader over the uncompressed data.
17    ///
18    /// The given `order` must be between [`PPMD8_MIN_ORDER`] and [`PPMD8_MAX_ORDER`] (inclusive).
19    /// The given `mem_size` must be between [`PPMD8_MIN_MEM_SIZE`] and [`PPMD8_MAX_MEM_SIZE`] (inclusive).
20    pub fn new(
21        reader: R,
22        order: u32,
23        mem_size: u32,
24        restore_method: RestoreMethod,
25    ) -> crate::Result<Self> {
26        if !(PPMD8_MIN_ORDER..=PPMD8_MAX_ORDER).contains(&order)
27            || !(PPMD8_MIN_MEM_SIZE..=PPMD8_MAX_MEM_SIZE).contains(&mem_size)
28        {
29            return Err(Error::InvalidParameter);
30        }
31
32        let ppmd = Ppmd8::new_decoder(reader, mem_size, order, restore_method)?;
33
34        Ok(Self {
35            ppmd,
36            finished: false,
37        })
38    }
39
40    /// Returns the inner reader.
41    pub fn into_inner(self) -> R {
42        self.ppmd.into_inner()
43    }
44}
45
46impl<R: Read> Read for Ppmd8Decoder<R> {
47    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
48        if self.finished {
49            return Ok(0);
50        }
51
52        if buf.is_empty() {
53            return Ok(0);
54        }
55
56        let mut sym = 0;
57        let mut decoded = 0;
58
59        unsafe {
60            for byte in buf.iter_mut() {
61                sym = self.ppmd.decode_symbol()?;
62
63                if sym < 0 {
64                    break;
65                }
66
67                *byte = sym as u8;
68                decoded += 1;
69            }
70        }
71
72        let code = self.ppmd.range_decoder_code();
73
74        if sym >= 0 && (!self.finished || decoded != buf.len() || code == 0) {
75            return Ok(decoded);
76        }
77
78        self.finished = true;
79
80        if sym != SYM_END || code != 0 {
81            return Err(std::io::Error::new(
82                std::io::ErrorKind::InvalidData,
83                "Error during PPMd decoding",
84            ));
85        }
86
87        Ok(decoded)
88    }
89}
ppmd_rust/decoder_8.rs

ppmd_rust/
decoder_8.rs
