ppmd_rust/
encoder_7.rs

1use crate::Error;
2use crate::byte_writer::ByteWriter;
3use crate::memory::Memory;
4use ppmd_sys::{
5    CPpmd7, PPMD7_MAX_MEM_SIZE, PPMD7_MAX_ORDER, PPMD7_MIN_MEM_SIZE, PPMD7_MIN_ORDER, Ppmd7_Alloc,
6    Ppmd7_Construct, Ppmd7_Init, Ppmd7z_EncodeSymbols, Ppmd7z_Flush_RangeEnc, Ppmd7z_Init_RangeEnc,
7};
8use std::io::Write;
9
10/// An encoder to encode data using PPMd7 (PPMdH) with the 7z range coder.
11pub struct Ppmd7Encoder<W: Write> {
12    ppmd: CPpmd7,
13    writer: ByteWriter<W>,
14    _memory: Memory,
15}
16
17impl<W: Write> Ppmd7Encoder<W> {
18    /// Creates a new [`Ppmd7Encoder`].
19    pub fn new(writer: W, 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 mut ppmd = unsafe { std::mem::zeroed::<CPpmd7>() };
27        unsafe { Ppmd7_Construct(&mut ppmd) };
28
29        let mut memory = Memory::new(mem_size);
30
31        let success = unsafe { Ppmd7_Alloc(&mut ppmd, mem_size, memory.allocation()) };
32
33        if success == 0 {
34            return Err(Error::InternalError("Failed to initialize range decoder"));
35        }
36
37        let mut writer = ByteWriter::new(writer);
38        let range_encoder = unsafe { &mut ppmd.rc.enc };
39        range_encoder.Stream = writer.byte_out_ptr();
40
41        unsafe { Ppmd7z_Init_RangeEnc(&mut ppmd) };
42        unsafe { Ppmd7_Init(&mut ppmd, order) };
43
44        Ok(Self {
45            ppmd,
46            writer,
47            _memory: memory,
48        })
49    }
50
51    fn inner_flush(&mut self) {
52        unsafe { Ppmd7z_Flush_RangeEnc(&mut self.ppmd) };
53        self.writer.flush();
54    }
55}
56
57impl<W: Write> Write for Ppmd7Encoder<W> {
58    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
59        if buf.is_empty() {
60            return Ok(0);
61        }
62
63        let pointer_range = buf.as_ptr_range();
64        unsafe { Ppmd7z_EncodeSymbols(&mut self.ppmd, pointer_range.start, pointer_range.end) };
65
66        Ok(buf.len())
67    }
68
69    fn flush(&mut self) -> std::io::Result<()> {
70        self.inner_flush();
71        Ok(())
72    }
73}
74
75#[cfg(test)]
76mod test {
77    use super::Ppmd7Encoder;
78    use crate::Ppmd7Decoder;
79    use std::io::{Read, Write};
80
81    const ORDER: u32 = 8;
82    const MEM_SIZE: u32 = 262144;
83
84    #[test]
85    fn ppmd7encoder_init_drop() {
86        let writer = Vec::new();
87        let encoder = Ppmd7Encoder::new(writer, ORDER, MEM_SIZE).unwrap();
88        assert!(!encoder.ppmd.Base.is_null());
89    }
90
91    #[test]
92    fn ppmd7encoder_encode_decode() {
93        let test_data = "Lorem ipsum dolor sit amet. ";
94
95        let mut writer = Vec::new();
96        {
97            let mut encoder = Ppmd7Encoder::new(&mut writer, ORDER, MEM_SIZE).unwrap();
98            encoder.write_all(test_data.as_bytes()).unwrap();
99            encoder.flush().unwrap();
100        }
101
102        let mut decoder = Ppmd7Decoder::new(writer.as_slice(), ORDER, MEM_SIZE).unwrap();
103
104        let mut decoded = vec![0; test_data.len()];
105        decoder.read_exact(&mut decoded).unwrap();
106
107        assert_eq!(decoded.as_slice(), test_data.as_bytes());
108
109        let decoded_data = String::from_utf8(decoded).unwrap();
110
111        assert_eq!(decoded_data, test_data);
112    }
113}
ppmd_rust/encoder_7.rs

ppmd_rust/
encoder_7.rs
