dvb_si/descriptors/
muxcode.rs

1//! Muxcode Descriptor — ISO/IEC 13818-1 §2.6.48, Table 2-79 (tag 0x21).
2//!
3//! Carries MuxCodeTableEntry() structures from ISO/IEC 14496-1 §11.2.4.3
4//! as opaque bytes.
5
6use super::descriptor_body;
7use crate::error::{Error, Result};
8use dvb_common::{Parse, Serialize};
9
10/// Descriptor tag for Muxcode_descriptor.
11pub const TAG: u8 = 0x21;
12const HEADER_LEN: usize = 2;
13
14/// Muxcode Descriptor.
15#[derive(Debug, Clone, PartialEq, Eq)]
16#[cfg_attr(feature = "serde", derive(serde::Serialize))]
17#[cfg_attr(feature = "yoke", derive(yoke::Yokeable))]
18pub struct MuxcodeDescriptor<'a> {
19    /// MuxCodeTableEntry() entries carried as opaque bytes.
20    #[cfg_attr(feature = "serde", serde(borrow))]
21    pub mux_code_table_entries: &'a [u8],
22}
23
24impl<'a> Parse<'a> for MuxcodeDescriptor<'a> {
25    type Error = crate::error::Error;
26
27    fn parse(bytes: &'a [u8]) -> Result<Self> {
28        let body = descriptor_body(
29            bytes,
30            TAG,
31            "MuxcodeDescriptor",
32            "unexpected tag for Muxcode_descriptor",
33        )?;
34        Ok(Self {
35            mux_code_table_entries: body,
36        })
37    }
38}
39
40impl Serialize for MuxcodeDescriptor<'_> {
41    type Error = crate::error::Error;
42
43    fn serialized_len(&self) -> usize {
44        HEADER_LEN + self.mux_code_table_entries.len()
45    }
46
47    fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
48        let len = self.serialized_len();
49        if buf.len() < len {
50            return Err(Error::OutputBufferTooSmall {
51                need: len,
52                have: buf.len(),
53            });
54        }
55        buf[0] = TAG;
56        buf[1] = self.mux_code_table_entries.len() as u8;
57        buf[HEADER_LEN..len].copy_from_slice(self.mux_code_table_entries);
58        Ok(len)
59    }
60}
61impl<'a> crate::traits::DescriptorDef<'a> for MuxcodeDescriptor<'a> {
62    const TAG: u8 = TAG;
63    const NAME: &'static str = "MUXCODE";
64}
65
66#[cfg(test)]
67mod tests {
68    use super::*;
69
70    #[test]
71    fn parse_empty() {
72        let d = MuxcodeDescriptor::parse(&[TAG, 0]).unwrap();
73        assert!(d.mux_code_table_entries.is_empty());
74    }
75
76    #[test]
77    fn parse_with_data() {
78        let bytes = [TAG, 3, 0xAA, 0xBB, 0xCC];
79        let d = MuxcodeDescriptor::parse(&bytes).unwrap();
80        assert_eq!(d.mux_code_table_entries, &[0xAA, 0xBB, 0xCC]);
81    }
82
83    #[test]
84    fn parse_rejects_wrong_tag() {
85        let err = MuxcodeDescriptor::parse(&[0x02, 0]).unwrap_err();
86        assert!(matches!(err, Error::InvalidDescriptor { tag: 0x02, .. }));
87    }
88
89    #[test]
90    fn serialize_round_trip() {
91        let d = MuxcodeDescriptor {
92            mux_code_table_entries: &[0x11, 0x22, 0x33],
93        };
94        let mut buf = vec![0u8; d.serialized_len()];
95        d.serialize_into(&mut buf).unwrap();
96        let reparsed = MuxcodeDescriptor::parse(&buf).unwrap();
97        assert_eq!(d, reparsed);
98    }
99
100    #[test]
101    fn serialize_rejects_small_buffer() {
102        let d = MuxcodeDescriptor {
103            mux_code_table_entries: &[1, 2],
104        };
105        let mut tiny = vec![0u8; 2];
106        let err = d.serialize_into(&mut tiny).unwrap_err();
107        assert!(matches!(err, Error::OutputBufferTooSmall { .. }));
108    }
109}
dvb_si/descriptors/muxcode.rs

dvb_si/descriptors/
muxcode.rs
