Skip to content

Commit

Permalink
Fix symbol IDs assigned to encoding packets
Browse files Browse the repository at this point in the history 
Previously, we incorrectly assigned internal symbol IDs (ISIs) to the
`PayloadId` of `EncodingPacket`s. According to RFC 6330, it should be
the encoding symbol IDs (ESIs). This commit fixes this inconsistency.

BREAKING CHANGE: As the assignment of symbol IDs changes, encoding
packets generated before this change cannot be decoded by the new
version and vice-versa.
  • Loading branch information
@mlegner @cberner
mlegner authored and cberner committed Mar 12, 2024
1 parent 06a8f67 commit da79ac2
Show file tree
Hide file tree
Showing 2 changed files with 92 additions and 57 deletions.
112 changes: 58 additions & 54 deletions src/decoder.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -155,10 +155,6 @@ impl SourceBlockDecoder {
) -> SourceBlockDecoder {
let source_symbols = int_div_ceil(block_length, config.symbol_size() as u64);

let mut received_esi = Set::new();
for i in source_symbols..extended_source_block_symbols(source_symbols) {
received_esi.insert(i);
}
SourceBlockDecoder {
source_block_id,
symbol_size: config.symbol_size(),
Expand All @@ -168,7 +164,7 @@ impl SourceBlockDecoder {
source_symbols: vec![None; source_symbols as usize],
repair_packets: vec![],
received_source_symbols: 0,
received_esi,
received_esi: Set::new(),
decoded: false,
sparse_threshold: SPARSE_MATRIX_THRESHOLD,
}
Expand Down Expand Up @@ -253,15 +249,12 @@ impl SourceBlockDecoder {
);

let (payload_id, payload) = packet.split();
let num_extended_symbols = extended_source_block_symbols(self.source_block_symbols);
if self.received_esi.insert(payload_id.encoding_symbol_id()) {
if payload_id.encoding_symbol_id() >= num_extended_symbols {
if payload_id.encoding_symbol_id() >= self.source_block_symbols {
// Repair symbol
self.repair_packets
.push(EncodingPacket::new(payload_id, payload));
} else {
// Check that this is not an extended symbol (which aren't explicitly sent)
assert!(payload_id.encoding_symbol_id() < self.source_block_symbols);
// Source symbol
self.source_symbols[payload_id.encoding_symbol_id() as usize] =
Some(Symbol::new(payload));
Expand All @@ -271,6 +264,14 @@ impl SourceBlockDecoder {
}

let num_extended_symbols = extended_source_block_symbols(self.source_block_symbols);
let num_padding_symbols = num_extended_symbols - self.source_block_symbols;

// Case 1: the number of received packets is insufficient for decoding
if self.received_esi.len() < self.source_block_symbols as usize {
return None;
}

// Case 2: we have all source symbols and can return them without decoding
if self.received_source_symbols == self.source_block_symbols {
let mut result =
vec![0; self.symbol_size as usize * self.source_block_symbols as usize];
Expand All @@ -282,46 +283,46 @@ impl SourceBlockDecoder {
return Some(result);
}

if self.received_esi.len() as u32 >= num_extended_symbols {
let s = num_ldpc_symbols(self.source_block_symbols) as usize;
let h = num_hdpc_symbols(self.source_block_symbols) as usize;

let mut encoded_indices = vec![];
// See section 5.3.3.4.2. There are S + H zero symbols to start the D vector
let mut d = vec![Symbol::zero(self.symbol_size); s + h];
for (i, source) in self.source_symbols.iter().enumerate() {
if let Some(symbol) = source {
encoded_indices.push(i as u32);
d.push(symbol.clone());
}
// Case 3: we may have sufficient symbols to do a standard decoding
let s = num_ldpc_symbols(self.source_block_symbols) as usize;
let h = num_hdpc_symbols(self.source_block_symbols) as usize;

let mut encoded_isis = vec![];
// See section 5.3.3.4.2. There are S + H zero symbols to start the D vector
let mut d = vec![Symbol::zero(self.symbol_size); s + h];
for (i, source) in self.source_symbols.iter().enumerate() {
if let Some(symbol) = source {
encoded_isis.push(i as u32);
d.push(symbol.clone());
}
}

// Append the extended padding symbols
for i in self.source_block_symbols..num_extended_symbols {
encoded_indices.push(i);
d.push(Symbol::zero(self.symbol_size));
}
// Append the extended padding symbols
for i in self.source_block_symbols..num_extended_symbols {
encoded_isis.push(i);
d.push(Symbol::zero(self.symbol_size));
}

for repair_packet in self.repair_packets.iter() {
encoded_indices.push(repair_packet.payload_id.encoding_symbol_id());
d.push(Symbol::new(repair_packet.data.clone()));
}
// Append the received repair symbols
for repair_packet in self.repair_packets.iter() {
// We need to convert from ESI to ISI
encoded_isis.push(repair_packet.payload_id.encoding_symbol_id() + num_padding_symbols);
d.push(Symbol::new(repair_packet.data.clone()));
}

if extended_source_block_symbols(self.source_block_symbols) >= self.sparse_threshold {
let (constraint_matrix, hdpc) = generate_constraint_matrix::<SparseBinaryMatrix>(
self.source_block_symbols,
&encoded_indices,
);
return self.try_pi_decode(constraint_matrix, hdpc, d);
} else {
let (constraint_matrix, hdpc) = generate_constraint_matrix::<DenseBinaryMatrix>(
self.source_block_symbols,
&encoded_indices,
);
return self.try_pi_decode(constraint_matrix, hdpc, d);
}
if num_extended_symbols >= self.sparse_threshold {
let (constraint_matrix, hdpc) = generate_constraint_matrix::<SparseBinaryMatrix>(
self.source_block_symbols,
&encoded_isis,
);
self.try_pi_decode(constraint_matrix, hdpc, d)
} else {
let (constraint_matrix, hdpc) = generate_constraint_matrix::<DenseBinaryMatrix>(
self.source_block_symbols,
&encoded_isis,
);
self.try_pi_decode(constraint_matrix, hdpc, d)
}
None
}

fn rebuild_source_symbol(
Expand All @@ -346,16 +347,6 @@ impl SourceBlockDecoder {
#[cfg(feature = "std")]
#[cfg(test)]
mod codec_tests {
#[cfg(not(feature = "python"))]
use crate::Decoder;
use crate::SourceBlockEncoder;
use crate::SourceBlockEncodingPlan;
#[cfg(not(feature = "python"))]
use crate::{Encoder, EncoderBuilder};
use crate::{ObjectTransmissionInformation, SourceBlockDecoder};
#[cfg(not(feature = "python"))]
use rand::seq::SliceRandom;
use rand::Rng;
use std::{
iter,
sync::{
Expand All @@ -365,6 +356,19 @@ mod codec_tests {
vec::Vec,
};

#[cfg(not(feature = "python"))]
use rand::seq::SliceRandom;
use rand::Rng;

#[cfg(not(feature = "python"))]
use crate::Decoder;
#[cfg(not(feature = "python"))]
use crate::{Encoder, EncoderBuilder};
use crate::{
ObjectTransmissionInformation, SourceBlockDecoder, SourceBlockEncoder,
SourceBlockEncodingPlan,
};

#[cfg(not(feature = "python"))]
#[test]
fn random_erasure_dense() {
Expand Down
37 changes: 34 additions & 3 deletions src/encoder.rs
View file
Original file line number Diff line number Diff line change
Expand Up @@ -321,7 +321,10 @@ impl SourceBlockEncoder {
for i in 0..packets {
let tuple = intermediate_tuple(start_encoding_symbol_id + i, lt_symbols, sys_index, p1);
result.push(EncodingPacket::new(
PayloadId::new(self.source_block_id, start_encoding_symbol_id + i),
PayloadId::new(
self.source_block_id,
self.source_symbols.len() as u32 + start_repair_symbol_id + i,
),
enc(
self.source_symbols.len() as u32,
&self.intermediate_symbols,
Expand Down Expand Up @@ -443,15 +446,16 @@ mod tests {
use rand::Rng;
use std::vec::Vec;

use super::*;

use crate::base::intermediate_tuple;
use crate::encoder::enc;
use crate::encoder::gen_intermediate_symbols;
use crate::symbol::Symbol;
use crate::systematic_constants::num_lt_symbols;
use crate::systematic_constants::num_pi_symbols;
use crate::systematic_constants::{
calculate_p1, num_ldpc_symbols, systematic_index, MAX_SOURCE_SYMBOLS_PER_BLOCK,
};
use crate::PayloadId;
#[cfg(not(feature = "python"))]
use crate::{Encoder, EncoderBuilder, EncodingPacket, ObjectTransmissionInformation};
#[cfg(not(feature = "python"))]
Expand Down Expand Up @@ -555,6 +559,33 @@ mod tests {
}
}

#[test]
fn encoding_creates_expected_packets() {
let symbol_size = 2;
let data: [u8; 6] = [0, 1, 2, 3, 4, 5];
let encoder = SourceBlockEncoder::new2(
0,
&ObjectTransmissionInformation::new(0, symbol_size, 1, 1, 1),
&data,
);
assert_eq!(
encoder.source_packets(),
[[0, 1], [2, 3], [4, 5]]
.into_iter()
.enumerate()
.map(|(i, d)| EncodingPacket::new(PayloadId::new(0, i as u32), d.into()))
.collect::<Vec<_>>()
);
assert_eq!(
encoder
.repair_packets(2, 4)
.into_iter()
.map(|p| p.payload_id.encoding_symbol_id())
.collect::<Vec<_>>(),
&[5, 6, 7, 8]
);
}

#[cfg(not(feature = "python"))]
#[test]
fn test_builder() {
Expand Down

0 comments on commit da79ac2

Please sign in to comment.