dvb-si 13.0.0

ETSI EN 300 468 DVB Service Information parser + builder. MPEG-2 PSI included.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90

//! Estimated Download Time Descriptor — ETSI EN 301 192 V1.7.1 §10.2.8,
//! Table 56 (data-carousel tag 0x07). PDF p.67, transcribed in
//! `private/specs-verified/dvb/dvb-si/descriptors/en_301_192/56-*.md`, verified against the rendered page.
//!
//! `est_download_time`(32): estimated download time of a module or group, in
//! seconds.

use crate::descriptors::{descriptor_body, write_descriptor_header};
use crate::error::{Error, Result};
use broadcast_common::len::need_out;
use broadcast_common::{Parse, Serialize};

/// Descriptor tag for est_download_time_descriptor (data-carousel namespace).
pub const TAG: u8 = 0x07;
const HEADER_LEN: usize = 2;
const BODY_LEN: usize = 4;

/// Estimated Download Time Descriptor (carousel tag 0x07).
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[cfg_attr(feature = "serde", derive(serde::Serialize))]
pub struct EstDownloadTimeDescriptor {
    /// `est_download_time` — estimated download time in seconds.
    pub est_download_time: u32,
}

impl<'a> Parse<'a> for EstDownloadTimeDescriptor {
    type Error = crate::error::Error;
    fn parse(bytes: &'a [u8]) -> Result<Self> {
        let body = descriptor_body(
            bytes,
            TAG,
            "EstDownloadTimeDescriptor",
            "unexpected tag for est_download_time_descriptor",
        )?;
        let b: [u8; BODY_LEN] = body.try_into().map_err(|_| Error::InvalidDescriptor {
            tag: TAG,
            reason: "est_download_time_descriptor body must be 4 bytes",
        })?;
        Ok(Self {
            est_download_time: u32::from_be_bytes(b),
        })
    }
}

impl Serialize for EstDownloadTimeDescriptor {
    type Error = crate::error::Error;
    fn serialized_len(&self) -> usize {
        HEADER_LEN + BODY_LEN
    }

    fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
        let len = self.serialized_len();
        need_out(buf, len)?;
        write_descriptor_header(buf, TAG, BODY_LEN)?;
        buf[2..6].copy_from_slice(&self.est_download_time.to_be_bytes());
        Ok(len)
    }
}

impl crate::traits::DescriptorDef<'_> for EstDownloadTimeDescriptor {
    const TAG: u8 = TAG;
    const NAME: &'static str = "EST_DOWNLOAD_TIME";
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn parse_and_round_trip() {
        let bytes = [TAG, 4, 0x00, 0x00, 0x01, 0x2C];
        let d = EstDownloadTimeDescriptor::parse(&bytes).unwrap();
        assert_eq!(d.est_download_time, 300);
        let mut out = [0u8; 6];
        d.serialize_into(&mut out).unwrap();
        assert_eq!(out, bytes);
    }

    #[test]
    fn wrong_length_rejected() {
        assert!(matches!(
            &(EstDownloadTimeDescriptor::parse(&[TAG, 3, 0, 0, 0])),
            Err(crate::error::Error::InvalidDescriptor { .. })
        ));
        assert!(matches!(
            &(EstDownloadTimeDescriptor::parse(&[TAG, 5, 0, 0, 0, 0, 0])),
            Err(crate::error::Error::InvalidDescriptor { .. })
        ));
    }
}