add CCSDS C2 r=7/8 code

src/cli.rs

@@ -10,6 +10,7 @@ use std::error::Error;
 
 pub mod ber;
 pub mod ccsds;
+pub mod ccsds_c2;
 pub mod dvbs2;
 pub mod encode;
 pub mod mackay_neal;
@@ -29,7 +30,10 @@ pub enum Args {
     BER(ber::Args),
     /// ccsds subcommand
     CCSDS(ccsds::Args),
-    /// encode subcommand,
+    /// ccsds-c2 subcommand
+    #[allow(non_camel_case_types)]
+    CCSDS_C2(ccsds_c2::Args),
+    /// encode subcommand
     Encode(encode::Args),
     /// dvbs2 subcommand
     DVBS2(dvbs2::Args),
@@ -44,6 +48,7 @@ impl Run for Args {
         match self {
             Args::BER(x) => x.run(),
             Args::CCSDS(x) => x.run(),
+            Args::CCSDS_C2(x) => x.run(),
             Args::DVBS2(x) => x.run(),
             Args::Encode(x) => x.run(),
             Args::MackayNeal(x) => x.run(),

src/cli/ccsds.rs

@@ -1,7 +1,7 @@
 //! CCSDS CLI subcommand
 //!
-//! This subcommand can be used to generate the LDPC codes described in the
-//! CCSDS TM Synchronization and Channel Coding Blue Book.  standard. It will
+//! This subcommand can be used to generate the AR4JA LDPC codes described in
+//! the CCSDS TM Synchronization and Channel Coding Blue Book standard. It will
 //! print the alist of the parity check matrix to `stdout` and optionally
 //! compute and print the girth of the Tanner graph. See [`crate::codes::ccsds`]
 //! for more information about the CCSDS LDPC codes.

src/cli/ccsds_c2.rs

@@ -0,0 +1,30 @@
+//! CCSDS C2 CLI subcommand
+//!
+//! This subcommand can be used to generate the C2 LDPC code (rate ~7/8)
+//! described in the CCSDS TM Synchronization and Channel Coding Blue Book
+//! standard. It will print the alist of the parity check matrix to
+//! `stdout`. See [`crate::codes::ccsds`] for more information about the CCSDS
+//! LDPC codes.
+//!
+//! # Examples
+//! The parity check matrix can be generated with
+//! ```shell
+//! $ ldpc-toolbox ccsds-c2
+//! ```
+
+use crate::cli::*;
+use crate::codes::ccsds::C2Code;
+use clap::Parser;
+
+/// CCSDS CLI arguments.
+#[derive(Debug, Parser)]
+#[command(about = "Generates the alist of CCSDS C2 LDPC")]
+pub struct Args {}
+
+impl Run for Args {
+    fn run(&self) -> std::result::Result<(), Box<dyn std::error::Error>> {
+        let h = C2Code::new().h();
+        print!("{}", h.alist());
+        Ok(())
+    }
+}

src/codes/ccsds.rs

@@ -1,10 +1,10 @@
-//! # CCSDS TM Synchronization and Channel Coding LDPC codes
+//! CCSDS TM Synchronization and Channel Coding LDPC codes.
 //!
-//! This module contains the AR4JA LDPC codes described in the TM
-//! Synchronization and Channel Coding Blue Book.
+//! This module contains the AR4JA LDPC codes and the C2 code described in the
+//! TM Synchronization and Channel Coding Blue Book.
 //!
 //! ## References
-//! \[1\] [CCSDS 131.0-B-4 TM Synchronization and Channel Coding Blue Book](https://public.ccsds.org/Pubs/131x0b4.pdf).
+//! \[1\] [CCSDS 131.0-B-5 TM Synchronization and Channel Coding Blue Book](https://public.ccsds.org/Pubs/131x0b5.pdf).
 
 use crate::sparse::SparseMatrix;
 use enum_iterator::Sequence;
@@ -335,6 +335,82 @@ static PHI_K: [[[usize; 7]; 26]; 4] = [
     ],
 ];
 
+/// C2 code definition.
+///
+/// This C2 code is the basic (8176, 7156) LDPC code. Expurgation, shortening
+/// and extension used to construct the (8160, 7136) code should be handled
+/// separately.
+#[derive(Copy, Clone, Debug, Eq, PartialEq, Hash, Default)]
+pub struct C2Code {}
+
+impl C2Code {
+    /// Creates a C2 code definition.
+    pub fn new() -> C2Code {
+        C2Code::default()
+    }
+
+    /// Constructs the parity check matrix for the code.
+    pub fn h(&self) -> SparseMatrix {
+        const N: usize = 511;
+        let mut h = SparseMatrix::new(Self::ROW_BLOCKS * N, Self::COL_BLOCKS * N);
+        for (row, circs) in C2_CIRCULANTS.iter().enumerate() {
+            for (col, circs) in circs.iter().enumerate() {
+                for &circ in circs.iter() {
+                    let circ = usize::from(circ);
+                    for j in 0..N {
+                        h.insert(row * N + j, col * N + (j + circ) % N);
+                    }
+                }
+            }
+        }
+        h
+    }
+
+    const ROW_BLOCKS: usize = 2;
+    const COL_BLOCKS: usize = 16;
+    const BLOCK_WEIGHT: usize = 2;
+}
+
+// Table 7-1 in CCSDS 131.0-B-5
+static C2_CIRCULANTS: [[[u16; C2Code::BLOCK_WEIGHT]; C2Code::COL_BLOCKS]; C2Code::ROW_BLOCKS] = [
+    [
+        [0, 176],
+        [12, 239],
+        [0, 352],
+        [24, 431],
+        [0, 392],
+        [151, 409],
+        [0, 351],
+        [9, 359],
+        [0, 307],
+        [53, 329],
+        [0, 207],
+        [18, 281],
+        [0, 399],
+        [202, 457],
+        [0, 247],
+        [36, 261],
+    ],
+    [
+        [99, 471],
+        [130, 473],
+        [198, 435],
+        [260, 478],
+        [215, 420],
+        [282, 481],
+        [48, 396],
+        [193, 445],
+        [273, 430],
+        [302, 451],
+        [96, 379],
+        [191, 386],
+        [244, 467],
+        [364, 470],
+        [51, 382],
+        [192, 414],
+    ],
+];
+
 #[cfg(test)]
 mod test {
     use super::*;