webrtc_media/io/sample_builder/
sample_sequence_location.rs

1use super::seqnum_distance;
2
3#[derive(Debug, PartialEq)]
4pub(crate) enum Comparison {
5    Void,
6    Before,
7    Inside,
8    After,
9}
10
11pub(crate) struct Iterator<'a, T> {
12    data: &'a [Option<T>],
13    sample: SampleSequenceLocation,
14    i: u16,
15}
16
17impl<'a, T> std::iter::Iterator for Iterator<'a, T> {
18    type Item = Option<&'a T>;
19
20    fn next(&mut self) -> Option<Self::Item> {
21        if self.sample.compare(self.i) == Comparison::Inside {
22            let old_i = self.i as usize;
23            self.i = self.i.wrapping_add(1);
24            return Some(self.data[old_i].as_ref());
25        }
26
27        None
28    }
29}
30
31#[derive(Debug, Clone, Copy)]
32pub(crate) struct SampleSequenceLocation {
33    /// head is the first packet in a sequence
34    pub(crate) head: u16,
35    /// tail is always set to one after the final sequence number,
36    /// so if `head == tail` then the sequence is empty
37    pub(crate) tail: u16,
38}
39
40impl SampleSequenceLocation {
41    pub(crate) fn new() -> Self {
42        Self { head: 0, tail: 0 }
43    }
44
45    pub(crate) fn empty(&self) -> bool {
46        self.head == self.tail
47    }
48
49    pub(crate) fn has_data(&self) -> bool {
50        self.head != self.tail
51    }
52
53    pub(crate) fn count(&self) -> u16 {
54        seqnum_distance(self.head, self.tail)
55    }
56
57    pub(crate) fn compare(&self, pos: u16) -> Comparison {
58        if self.head == self.tail {
59            return Comparison::Void;
60        }
61        if self.head < self.tail {
62            if self.head <= pos && pos < self.tail {
63                return Comparison::Inside;
64            }
65        } else if self.head <= pos || pos < self.tail {
66            return Comparison::Inside;
67        }
68        if self.head.wrapping_sub(pos) <= pos.wrapping_sub(self.tail) {
69            return Comparison::Before;
70        }
71        Comparison::After
72    }
73
74    pub(crate) fn range<'a, T>(&self, data: &'a [Option<T>]) -> Iterator<'a, T> {
75        Iterator {
76            data,
77            sample: *self,
78            i: self.head,
79        }
80    }
81}
webrtc_media/io/sample_builder/sample_sequence_location.rs

webrtc_media/io/sample_builder/
sample_sequence_location.rs
