reed_solomon_16/rate/
decoder_work.rs

1use fixedbitset::FixedBitSet;
2
3use crate::{
4    engine::{Shards, ShardsRefMut},
5    Error,
6};
7
8// ======================================================================
9// DecoderWork - PUBLIC
10
11/// Working space for [`RateDecoder`].
12///
13/// [`RateDecoder`]: crate::rate::RateDecoder
14pub struct DecoderWork {
15    original_count: usize,
16    recovery_count: usize,
17    shard_bytes: usize,
18
19    original_base_pos: usize,
20    recovery_base_pos: usize,
21
22    original_received_count: usize,
23    recovery_received_count: usize,
24    // May contain extra zero bits.
25    received: FixedBitSet,
26    shards: Shards,
27}
28
29impl DecoderWork {
30    /// Creates new [`DecoderWork`] which initially
31    /// has no working space allocated.
32    pub fn new() -> Self {
33        Self {
34            original_count: 0,
35            recovery_count: 0,
36            shard_bytes: 0,
37
38            original_base_pos: 0,
39            recovery_base_pos: 0,
40
41            original_received_count: 0,
42            recovery_received_count: 0,
43            received: FixedBitSet::new(),
44            shards: Shards::new(),
45        }
46    }
47}
48
49// ======================================================================
50// DecoderWork - IMPL Default
51
52impl Default for DecoderWork {
53    fn default() -> Self {
54        Self::new()
55    }
56}
57
58// ======================================================================
59// DecoderWork - CRATE
60
61impl DecoderWork {
62    pub(crate) fn add_original_shard<T: AsRef<[u8]>>(
63        &mut self,
64        index: usize,
65        original_shard: T,
66    ) -> Result<(), Error> {
67        let pos = self.original_base_pos + index;
68        let original_shard = original_shard.as_ref();
69
70        if index >= self.original_count {
71            Err(Error::InvalidOriginalShardIndex {
72                original_count: self.original_count,
73                index,
74            })
75        } else if self.received[pos] {
76            Err(Error::DuplicateOriginalShardIndex { index })
77        } else if original_shard.len() != self.shard_bytes {
78            Err(Error::DifferentShardSize {
79                shard_bytes: self.shard_bytes,
80                got: original_shard.len(),
81            })
82        } else {
83            self.shards[pos].copy_from_slice(original_shard);
84            self.original_received_count += 1;
85            self.received.set(pos, true);
86            Ok(())
87        }
88    }
89
90    pub(crate) fn add_recovery_shard<T: AsRef<[u8]>>(
91        &mut self,
92        index: usize,
93        recovery_shard: T,
94    ) -> Result<(), Error> {
95        let pos = self.recovery_base_pos + index;
96        let recovery_shard = recovery_shard.as_ref();
97
98        if index >= self.recovery_count {
99            Err(Error::InvalidRecoveryShardIndex {
100                recovery_count: self.recovery_count,
101                index,
102            })
103        } else if self.received[pos] {
104            Err(Error::DuplicateRecoveryShardIndex { index })
105        } else if recovery_shard.len() != self.shard_bytes {
106            Err(Error::DifferentShardSize {
107                shard_bytes: self.shard_bytes,
108                got: recovery_shard.len(),
109            })
110        } else {
111            self.shards[pos].copy_from_slice(recovery_shard);
112            self.recovery_received_count += 1;
113            self.received.set(pos, true);
114            Ok(())
115        }
116    }
117
118    // Begin decode.
119    // - Returned `FixedBitSet` may contain extra zero bits.
120    pub(crate) fn decode_begin(
121        &mut self,
122    ) -> Result<Option<(ShardsRefMut, usize, usize, &FixedBitSet)>, Error> {
123        if self.original_received_count + self.recovery_received_count < self.original_count {
124            Err(Error::NotEnoughShards {
125                original_count: self.original_count,
126                original_received_count: self.original_received_count,
127                recovery_received_count: self.recovery_received_count,
128            })
129        } else if self.original_received_count == self.original_count {
130            Ok(None)
131        } else {
132            Ok(Some((
133                self.shards.as_ref_mut(),
134                self.original_count,
135                self.recovery_count,
136                &self.received,
137            )))
138        }
139    }
140
141    pub(crate) fn original_count(&self) -> usize {
142        self.original_count
143    }
144
145    pub(crate) fn reset(
146        &mut self,
147        original_count: usize,
148        recovery_count: usize,
149        shard_bytes: usize,
150
151        original_base_pos: usize,
152        recovery_base_pos: usize,
153        work_count: usize,
154    ) {
155        self.original_count = original_count;
156        self.recovery_count = recovery_count;
157        self.shard_bytes = shard_bytes;
158
159        self.original_base_pos = original_base_pos;
160        self.recovery_base_pos = recovery_base_pos;
161
162        self.original_received_count = 0;
163        self.recovery_received_count = 0;
164
165        let max_received_pos = std::cmp::max(
166            original_base_pos + original_count,
167            recovery_base_pos + recovery_count,
168        );
169
170        self.received.clear();
171        if self.received.len() < max_received_pos {
172            self.received.grow(max_received_pos);
173        }
174
175        self.shards.resize(work_count, shard_bytes);
176    }
177
178    pub(crate) fn reset_received(&mut self) {
179        self.original_received_count = 0;
180        self.recovery_received_count = 0;
181        self.received.clear();
182    }
183
184    // This must only be called by `DecoderResult`.
185    pub(crate) fn restored_original(&self, index: usize) -> Option<&[u8]> {
186        let pos = self.original_base_pos + index;
187
188        if index < self.original_count && !self.received[pos] {
189            Some(&self.shards[pos])
190        } else {
191            None
192        }
193    }
194}
reed_solomon_16/rate/decoder_work.rs

reed_solomon_16/rate/
decoder_work.rs
