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
14impl<R: Read> Ppmd7Decoder<R> {
15    /// Creates a new [`Ppmd7Decoder`] which provides a reader over the uncompressed data.
16    ///
17    /// The given `order` must be between [`PPMD7_MIN_ORDER`] and [`PPMD7_MAX_ORDER`]
18    /// The given `mem_size` must be between [`PPMD7_MIN_MEM_SIZE`] and [`PPMD7_MAX_MEM_SIZE`]
19    pub fn new(reader: R, order: u32, mem_size: u32) -> crate::Result<Self> {
20        if !(PPMD7_MIN_ORDER..=PPMD7_MAX_ORDER).contains(&order)
21            || !(PPMD7_MIN_MEM_SIZE..=PPMD7_MAX_MEM_SIZE).contains(&mem_size)
22        {
23            return Err(Error::InvalidParameter);
24        }
25
26        let ppmd = Ppmd7::new_decoder(reader, order, mem_size)?;
27
28        Ok(Self {
29            ppmd,
30            finished: false,
31        })
32    }
33
34    /// Returns the inner reader.
35    pub fn into_inner(self) -> R {
36        self.ppmd.into_inner()
37    }
38}
39
40impl<R: Read> Read for Ppmd7Decoder<R> {
41    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
42        if self.finished {
43            return Ok(0);
44        }
45
46        if buf.is_empty() {
47            return Ok(0);
48        }
49
50        let mut sym = 0;
51        let mut decoded = 0;
52
53        for byte in buf.iter_mut() {
54            match self.ppmd.decode_symbol() {
55                Ok(symbol) => sym = symbol,
56                Err(err) => {
57                    self.finished = true;
58                    return Err(err);
59                }
60            }
61
62            if sym < 0 {
63                break;
64            }
65
66            *byte = sym as u8;
67            decoded += 1;
68        }
69
70        if sym >= 0 {
71            return Ok(decoded);
72        }
73
74        self.finished = true;
75
76        let code = self.ppmd.range_decoder_code();
77
78        if sym != SYM_END || code != 0 {
79            return Err(std::io::Error::new(
80                std::io::ErrorKind::InvalidData,
81                "Error during PPMd decoding",
82            ));
83        }
84
85        Ok(decoded)
86    }
87}
ppmd_rust/decoder_7.rs

ppmd_rust/
decoder_7.rs
