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
15unsafe impl<R: Read> Send for Ppmd8Decoder<R> {}
16unsafe impl<R: Read> Sync for Ppmd8Decoder<R> {}
17
18impl<R: Read> Ppmd8Decoder<R> {
19    /// Creates a new [`Ppmd8Decoder`] which provides a reader over the uncompressed data.
20    ///
21    /// The given `order` must be between [`PPMD8_MIN_ORDER`] and [`PPMD8_MAX_ORDER`] (inclusive).
22    /// The given `mem_size` must be between [`PPMD8_MIN_MEM_SIZE`] and [`PPMD8_MAX_MEM_SIZE`] (inclusive).
23    pub fn new(
24        reader: R,
25        order: u32,
26        mem_size: u32,
27        restore_method: RestoreMethod,
28    ) -> crate::Result<Self> {
29        if !(PPMD8_MIN_ORDER..=PPMD8_MAX_ORDER).contains(&order)
30            || !(PPMD8_MIN_MEM_SIZE..=PPMD8_MAX_MEM_SIZE).contains(&mem_size)
31        {
32            return Err(Error::InvalidParameter);
33        }
34
35        let ppmd = PPMd8::new_decoder(reader, order, mem_size, restore_method)?;
36
37        Ok(Self {
38            ppmd,
39            finished: false,
40        })
41    }
42
43    /// Returns the inner reader.
44    pub fn into_inner(self) -> R {
45        self.ppmd.into_inner()
46    }
47}
48
49impl<R: Read> Read for Ppmd8Decoder<R> {
50    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
51        if self.finished {
52            return Ok(0);
53        }
54
55        if buf.is_empty() {
56            return Ok(0);
57        }
58
59        let mut sym = 0;
60        let mut decoded = 0;
61
62        for byte in buf.iter_mut() {
63            match self.ppmd.decode_symbol() {
64                Ok(symbol) => sym = symbol,
65                Err(err) => {
66                    if err.kind() == std::io::ErrorKind::UnexpectedEof {
67                        self.finished = true;
68                        return Ok(decoded);
69                    }
70                    return Err(err);
71                }
72            }
73
74            if sym < 0 {
75                break;
76            }
77
78            *byte = sym as u8;
79            decoded += 1;
80        }
81
82        let code = self.ppmd.range_decoder_code();
83
84        if sym >= 0 {
85            return Ok(decoded);
86        }
87
88        self.finished = true;
89
90        if sym != SYM_END || code != 0 {
91            return Err(std::io::Error::new(
92                std::io::ErrorKind::InvalidData,
93                "Error during PPMd decoding",
94            ));
95        }
96
97        // END_MARKER detected
98        Ok(decoded)
99    }
100}
ppmd_rust/decoder_8.rs

ppmd_rust/
decoder_8.rs
