ppmd_rust/
decoder_7.rs

1use std::io::Read;
2
3use crate::{
4    internal::ppmd7::{PPMd7, RangeDecoder},
5    Error, PPMD7_MAX_MEM_SIZE, PPMD7_MAX_ORDER, PPMD7_MIN_MEM_SIZE, PPMD7_MIN_ORDER, SYM_END,
6};
7
8/// A decoder to decompress data using PPMd7 (PPMdH) with the 7z range coder.
9pub struct Ppmd7Decoder<R: Read> {
10    ppmd: PPMd7<RangeDecoder<R>>,
11    finished: bool,
12}
13
14unsafe impl<R: Read> Send for Ppmd7Decoder<R> {}
15unsafe impl<R: Read> Sync for Ppmd7Decoder<R> {}
16
17impl<R: Read> Ppmd7Decoder<R> {
18    /// Creates a new [`Ppmd7Decoder`] which provides a reader over the uncompressed data.
19    ///
20    /// The given `order` must be between [`PPMD7_MIN_ORDER`] and [`PPMD7_MAX_ORDER`]
21    /// The given `mem_size` must be between [`PPMD7_MIN_MEM_SIZE`] and [`PPMD7_MAX_MEM_SIZE`]
22    pub fn new(reader: R, order: u32, mem_size: u32) -> crate::Result<Self> {
23        if !(PPMD7_MIN_ORDER..=PPMD7_MAX_ORDER).contains(&order)
24            || !(PPMD7_MIN_MEM_SIZE..=PPMD7_MAX_MEM_SIZE).contains(&mem_size)
25        {
26            return Err(Error::InvalidParameter);
27        }
28
29        let ppmd = PPMd7::new_decoder(reader, order, mem_size)?;
30
31        Ok(Self {
32            ppmd,
33            finished: false,
34        })
35    }
36
37    /// Gets a reference to the underlying reader.
38    pub fn get_ref(&self) -> &R {
39        self.ppmd.get_ref()
40    }
41
42    /// Gets a mutable reference to the underlying reader.
43    ///
44    /// Note that mutation of the stream may result in surprising results if
45    /// this decoder is continued to be used.
46    pub fn get_mut(&mut self) -> &mut R {
47        self.ppmd.get_mut()
48    }
49
50    /// Returns the inner reader.
51    pub fn into_inner(self) -> R {
52        self.ppmd.into_inner()
53    }
54}
55
56impl<R: Read> Read for Ppmd7Decoder<R> {
57    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
58        if self.finished {
59            return Ok(0);
60        }
61
62        if buf.is_empty() {
63            return Ok(0);
64        }
65
66        let mut sym = 0;
67        let mut decoded = 0;
68
69        for byte in buf.iter_mut() {
70            match self.ppmd.decode_symbol() {
71                Ok(symbol) => sym = symbol,
72                Err(err) => {
73                    if err.kind() == std::io::ErrorKind::UnexpectedEof {
74                        self.finished = true;
75                        return Ok(decoded);
76                    }
77                    return Err(err);
78                }
79            }
80
81            if sym < 0 {
82                break;
83            }
84
85            *byte = sym as u8;
86            decoded += 1;
87        }
88
89        let code = self.ppmd.range_decoder_code();
90
91        if sym >= 0 {
92            return Ok(decoded);
93        }
94
95        self.finished = true;
96
97        if sym != SYM_END || code != 0 {
98            return Err(std::io::Error::new(
99                std::io::ErrorKind::InvalidData,
100                "Error during PPMd decoding",
101            ));
102        }
103
104        // END_MARKER detected
105        Ok(decoded)
106    }
107}
ppmd_rust/decoder_7.rs

ppmd_rust/
decoder_7.rs
