dvb_si/descriptors/
tva_id.rs

1//! TVA_id Descriptor — ETSI TS 102 323 §11.2.4, Table 114 (tag 0x75).
2//!
3//! Lists one or more TV-Anytime identifiers, each with a running_status that
4//! a receiver uses to drive its recording strategy. Per the TVA PDF
5//! (etsi_ts_102_323_v01.04.01, p. 101, Table 114) each loop entry is 3 bytes:
6//! TVA_id(16) + Reserved(5) + running_status(3). running_status values are
7//! defined in Table 115.
8
9use super::descriptor_body;
10use crate::error::{Error, Result};
11use dvb_common::{Parse, Serialize};
12
13/// Descriptor tag for TVA_id_descriptor.
14pub const TAG: u8 = 0x75;
15const HEADER_LEN: usize = 2;
16const ENTRY_LEN: usize = 3;
17
18/// Largest representable 3-bit running_status.
19const RUNNING_STATUS_MAX: u8 = 0x07;
20
21/// TVA running status — ETSI TS 102 323 Table 115.
22///
23/// NOTE: This is the TVA-specific running_status table, NOT the
24/// EN 300 468 Table 6 running_status.
25#[derive(Debug, Clone, Copy, PartialEq, Eq)]
26#[cfg_attr(feature = "serde", derive(serde::Serialize))]
27#[non_exhaustive]
28pub enum TvaRunningStatus {
29    /// 0 — reserved.
30    Reserved,
31    /// 1 — not yet running.
32    NotYetRunning,
33    /// 2 — starts shortly.
34    StartsShortly,
35    /// 3 — paused.
36    Paused,
37    /// 4 — running.
38    Running,
39    /// 5 — cancelled.
40    Cancelled,
41    /// 6 — completed.
42    Completed,
43    /// Unallocated wire value, preserved verbatim for round-trip.
44    Unallocated(u8),
45}
46
47impl TvaRunningStatus {
48    #[must_use]
49    /// Creates a value from a wire byte, preserving every possible
50    /// byte value for lossless round-trip.
51    pub fn from_u8(v: u8) -> Self {
52        match v {
53            0 => Self::Reserved,
54            1 => Self::NotYetRunning,
55            2 => Self::StartsShortly,
56            3 => Self::Paused,
57            4 => Self::Running,
58            5 => Self::Cancelled,
59            6 => Self::Completed,
60            v => Self::Unallocated(v),
61        }
62    }
63
64    #[must_use]
65    /// Returns the wire byte for this value.
66    pub fn to_u8(self) -> u8 {
67        match self {
68            Self::Reserved => 0,
69            Self::NotYetRunning => 1,
70            Self::StartsShortly => 2,
71            Self::Paused => 3,
72            Self::Running => 4,
73            Self::Cancelled => 5,
74            Self::Completed => 6,
75            Self::Unallocated(v) => v,
76        }
77    }
78
79    #[must_use]
80    /// Returns a human-readable spec name for this value.
81    pub fn name(self) -> &'static str {
82        match self {
83            Self::Reserved => "reserved",
84            Self::NotYetRunning => "not yet running",
85            Self::StartsShortly => "starts shortly",
86            Self::Paused => "paused",
87            Self::Running => "running",
88            Self::Cancelled => "cancelled",
89            Self::Completed => "completed",
90            Self::Unallocated(_) => "unallocated",
91        }
92    }
93}
94dvb_common::impl_spec_display!(TvaRunningStatus, Unallocated);
95
96/// One TVA_id loop entry.
97#[derive(Debug, Clone, PartialEq, Eq)]
98#[cfg_attr(feature = "serde", derive(serde::Serialize))]
99pub struct TvaIdEntry {
100    /// 16-bit TVA_id referencing the item of content.
101    pub tva_id: u16,
102    /// 3-bit running_status (Table 115).
103    pub running_status: TvaRunningStatus,
104}
105
106/// TVA_id Descriptor.
107#[derive(Debug, Clone, PartialEq, Eq)]
108#[cfg_attr(feature = "serde", derive(serde::Serialize))]
109pub struct TvaIdDescriptor {
110    /// Entries in wire order.
111    pub entries: Vec<TvaIdEntry>,
112}
113
114impl<'a> Parse<'a> for TvaIdDescriptor {
115    type Error = crate::error::Error;
116    fn parse(bytes: &'a [u8]) -> Result<Self> {
117        let body = descriptor_body(
118            bytes,
119            TAG,
120            "TvaIdDescriptor",
121            "unexpected tag for TVA_id_descriptor",
122        )?;
123        if body.len() % ENTRY_LEN != 0 {
124            return Err(Error::InvalidDescriptor {
125                tag: TAG,
126                reason: "TVA_id_descriptor length must be a multiple of 3",
127            });
128        }
129        let mut entries = Vec::with_capacity(body.len() / ENTRY_LEN);
130        for chunk in body.chunks_exact(ENTRY_LEN) {
131            let tva_id = u16::from_be_bytes([chunk[0], chunk[1]]);
132            let running_status = TvaRunningStatus::from_u8(chunk[2] & RUNNING_STATUS_MAX);
133            entries.push(TvaIdEntry {
134                tva_id,
135                running_status,
136            });
137        }
138        Ok(Self { entries })
139    }
140}
141
142impl Serialize for TvaIdDescriptor {
143    type Error = crate::error::Error;
144    fn serialized_len(&self) -> usize {
145        HEADER_LEN + self.entries.len() * ENTRY_LEN
146    }
147
148    fn serialize_into(&self, buf: &mut [u8]) -> Result<usize> {
149        for e in &self.entries {
150            if e.running_status.to_u8() > RUNNING_STATUS_MAX {
151                return Err(Error::InvalidDescriptor {
152                    tag: TAG,
153                    reason: "running_status exceeds 3 bits",
154                });
155            }
156        }
157        if self.entries.len() * ENTRY_LEN > u8::MAX as usize {
158            return Err(Error::InvalidDescriptor {
159                tag: TAG,
160                reason: "TVA_id_descriptor body exceeds 255 bytes",
161            });
162        }
163        let len = self.serialized_len();
164        if buf.len() < len {
165            return Err(Error::OutputBufferTooSmall {
166                need: len,
167                have: buf.len(),
168            });
169        }
170        buf[0] = TAG;
171        buf[1] = (self.entries.len() * ENTRY_LEN) as u8;
172        let mut pos = HEADER_LEN;
173        for e in &self.entries {
174            buf[pos..pos + 2].copy_from_slice(&e.tva_id.to_be_bytes());
175            // Reserved(5) emitted as 1s.
176            buf[pos + 2] = 0xF8 | (e.running_status.to_u8() & RUNNING_STATUS_MAX);
177            pos += ENTRY_LEN;
178        }
179        Ok(len)
180    }
181}
182impl<'a> crate::traits::DescriptorDef<'a> for TvaIdDescriptor {
183    const TAG: u8 = TAG;
184    const NAME: &'static str = "TVA_ID";
185}
186
187#[cfg(test)]
188mod tests {
189    use super::*;
190
191    #[test]
192    fn parse_single_entry() {
193        // TVA_id=0x1234, running_status=4 (running), reserved bits set.
194        let bytes = [TAG, 3, 0x12, 0x34, 0xFC];
195        let d = TvaIdDescriptor::parse(&bytes).unwrap();
196        assert_eq!(d.entries.len(), 1);
197        assert_eq!(d.entries[0].tva_id, 0x1234);
198        assert_eq!(d.entries[0].running_status, TvaRunningStatus::Running);
199    }
200
201    #[test]
202    fn parse_multiple_entries() {
203        let bytes = [TAG, 6, 0x00, 0x01, 0x01, 0xAB, 0xCD, 0x06];
204        let d = TvaIdDescriptor::parse(&bytes).unwrap();
205        assert_eq!(d.entries.len(), 2);
206        assert_eq!(d.entries[0].tva_id, 0x0001);
207        assert_eq!(d.entries[0].running_status, TvaRunningStatus::NotYetRunning);
208        assert_eq!(d.entries[1].tva_id, 0xABCD);
209        assert_eq!(d.entries[1].running_status, TvaRunningStatus::Completed);
210    }
211
212    #[test]
213    fn parse_ignores_reserved_bits() {
214        let bytes = [TAG, 3, 0x00, 0x00, 0xFF];
215        let d = TvaIdDescriptor::parse(&bytes).unwrap();
216        assert_eq!(
217            d.entries[0].running_status,
218            TvaRunningStatus::Unallocated(0x07)
219        );
220    }
221
222    #[test]
223    fn parse_rejects_wrong_tag() {
224        assert!(matches!(
225            TvaIdDescriptor::parse(&[0x74, 0]).unwrap_err(),
226            Error::InvalidDescriptor { tag: 0x74, .. }
227        ));
228    }
229
230    #[test]
231    fn parse_rejects_length_not_multiple_of_3() {
232        let bytes = [TAG, 2, 0, 0];
233        assert!(matches!(
234            TvaIdDescriptor::parse(&bytes).unwrap_err(),
235            Error::InvalidDescriptor { .. }
236        ));
237    }
238
239    #[test]
240    fn empty_descriptor_valid() {
241        let bytes = [TAG, 0];
242        let d = TvaIdDescriptor::parse(&bytes).unwrap();
243        assert!(d.entries.is_empty());
244    }
245
246    #[test]
247    fn serialize_round_trip() {
248        let d = TvaIdDescriptor {
249            entries: vec![
250                TvaIdEntry {
251                    tva_id: 0x1000,
252                    running_status: TvaRunningStatus::StartsShortly,
253                },
254                TvaIdEntry {
255                    tva_id: 0xFFFF,
256                    running_status: TvaRunningStatus::Reserved,
257                },
258            ],
259        };
260        let mut buf = vec![0u8; d.serialized_len()];
261        d.serialize_into(&mut buf).unwrap();
262        assert_eq!(TvaIdDescriptor::parse(&buf).unwrap(), d);
263    }
264
265    #[test]
266    fn serialize_rejects_running_status_over_range() {
267        let d = TvaIdDescriptor {
268            entries: vec![TvaIdEntry {
269                tva_id: 0,
270                running_status: TvaRunningStatus::Unallocated(0x08),
271            }],
272        };
273        let mut buf = vec![0u8; d.serialized_len()];
274        assert!(matches!(
275            d.serialize_into(&mut buf).unwrap_err(),
276            Error::InvalidDescriptor { .. }
277        ));
278    }
279
280    #[cfg(feature = "serde")]
281    #[test]
282    fn serde_round_trip() {
283        let d = TvaIdDescriptor {
284            entries: vec![TvaIdEntry {
285                tva_id: 0x4242,
286                running_status: TvaRunningStatus::Running,
287            }],
288        };
289        let j = serde_json::to_string(&d).unwrap();
290        // Serialize-only: assert the emitted JSON re-parses (serialize-stable).
291        let _v: serde_json::Value = serde_json::from_str(&j).unwrap();
292    }
293
294    #[test]
295    fn tva_running_status_full_range_round_trip() {
296        for b in 0..=0xFF_u8 {
297            let rs = TvaRunningStatus::from_u8(b);
298            assert_eq!(rs.to_u8(), b, "round-trip failed for byte 0x{b:02X}");
299        }
300    }
301
302    #[test]
303    fn tva_running_status_name_for_known() {
304        assert_eq!(TvaRunningStatus::NotYetRunning.name(), "not yet running");
305        assert_eq!(TvaRunningStatus::Running.name(), "running");
306        assert_eq!(TvaRunningStatus::Completed.name(), "completed");
307        assert_eq!(TvaRunningStatus::Unallocated(0x07).name(), "unallocated");
308    }
309}
dvb_si/descriptors/tva_id.rs

dvb_si/descriptors/
tva_id.rs
