dvb_si/descriptors/extension/
message.rs

1//! Message Descriptor — ETSI EN 300 468 §6.4.9 (tag_extension 0x08).
2use super::*;
3
4impl<'a> ExtensionBodyDef<'a> for Message<'a> {
5    const TAG_EXTENSION: u8 = 0x08;
6    const NAME: &'static str = "MESSAGE";
7}
8/// message body (Table 148).
9#[derive(Debug, Clone, PartialEq, Eq)]
10#[cfg_attr(feature = "serde", derive(serde::Serialize))]
11#[cfg_attr(feature = "yoke", derive(yoke::Yokeable))]
12pub struct Message<'a> {
13    /// message_id(8).
14    pub message_id: u8,
15    /// ISO_639_language_code(24).
16    pub iso_639_language_code: LangCode,
17    /// DVB Annex-A encoded text_char run (remainder of body).
18    pub text: DvbText<'a>,
19}
20
21impl<'a> Parse<'a> for Message<'a> {
22    type Error = crate::error::Error;
23    fn parse(sel: &'a [u8]) -> Result<Self> {
24        if sel.len() < 1 + ISO_639_LEN {
25            return Err(Error::BufferTooShort {
26                need: 1 + ISO_639_LEN,
27                have: sel.len(),
28                what: "message body",
29            });
30        }
31        Ok(Message {
32            message_id: sel[0],
33            iso_639_language_code: LangCode([sel[1], sel[2], sel[3]]),
34            text: DvbText::new(&sel[1 + ISO_639_LEN..]),
35        })
36    }
37}
38
39impl Serialize for Message<'_> {
40    type Error = crate::error::Error;
41    fn serialized_len(&self) -> usize {
42        1 + ISO_639_LEN + self.text.len()
43    }
44    fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
45        let len = self.serialized_len();
46        if buf.len() < len {
47            return Err(Error::OutputBufferTooSmall {
48                need: len,
49                have: buf.len(),
50            });
51        }
52        buf[0] = self.message_id;
53        buf[1..1 + ISO_639_LEN].copy_from_slice(&self.iso_639_language_code.0);
54        buf[1 + ISO_639_LEN..len].copy_from_slice(self.text.raw());
55        Ok(len)
56    }
57}
58
59#[cfg(test)]
60mod tests {
61    use super::*;
62    use crate::descriptors::extension::test_support::*;
63    use crate::descriptors::extension::{ExtensionBody, ExtensionDescriptor};
64    use crate::text::LangCode;
65
66    #[test]
67    fn parse_message() {
68        let sel = [0x07, b'e', b'n', b'g', b'H', b'i'];
69        let bytes = wrap(0x08, &sel);
70        let d = ExtensionDescriptor::parse(&bytes).unwrap();
71        match &d.body {
72            ExtensionBody::Message(b) => {
73                assert_eq!(b.message_id, 0x07);
74                assert_eq!(b.iso_639_language_code, LangCode(*b"eng"));
75                assert_eq!(b.text.raw(), b"Hi");
76            }
77            other => panic!("expected Message, got {other:?}"),
78        }
79        round_trip(&d);
80    }
81}
dvb_si/descriptors/extension/message.rs

dvb_si/descriptors/extension/
message.rs
