CCSDS Synchronization and Channel Coding (131.0-B, 231.0-B)
ocaml-scc: rewrite README examples to typecheck
The Usage block had unbound [tc_frame] / [frame] / [raw_bytes] free
variables. Wrap each flow in a function ([uplink], [downlink],
[feed_cltus]). The Eio transport block referenced a single [flow]
used as both source and sink, mismatched [(_, [`Transport e])] /
[(_, [`Error of string])] error variants, and missed the [`Error _]
case. Take [~source] / [~sink] separately, handle every error
variant via [Fmt.epr], and add [eio] / [eio.core] / [fmt] mdx
libraries.
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README.md
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README.md
···
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## Usage
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```ocaml
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(* TC uplink: frame -> CLTU *)
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let cltu = Scc.Sync.Cltu.encode tc_frame
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(* TC uplink: frame -> CLTU. *)
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let uplink tc_frame = Scc.Sync.Cltu.encode tc_frame
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(* TM downlink: randomize + RS encode + convolutional encode *)
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let r = Scc.Coding.Randomizer.create ()
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let () = Scc.Coding.Randomizer.apply r frame 0 (Bytes.length frame)
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let codeword = Scc.Coding.Reed_solomon.encode ~interleave:I5 frame
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let coded = Scc.Coding.Convolutional.encode codeword
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(* TM downlink: randomize + RS encode + convolutional encode. *)
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let downlink frame =
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let r = Scc.Coding.Randomizer.create () in
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Scc.Coding.Randomizer.apply r frame 0 (Bytes.length frame);
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let codeword = Scc.Coding.Reed_solomon.encode ~interleave:I5 frame in
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Scc.Coding.Convolutional.encode codeword
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(* Stream parsing: extract CLTUs from raw bytes *)
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let state = ref (Scc.Sync.Cltu_sync.init ())
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let () =
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let new_state, result = Scc.Sync.Cltu_sync.feed !state raw_bytes in
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state := new_state;
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ignore result
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(* Stream parsing: extract CLTUs from raw bytes. *)
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let feed_cltus state raw_bytes =
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let new_state, result = Scc.Sync.Cltu_sync.feed state raw_bytes in
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(new_state, result)
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```
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## Eio Transport (`scc-eio`)
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The `scc-eio` package provides Eio flow-based send/recv:
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```ocaml
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let () =
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(* Receive CLTU-framed TC from a raw byte stream *)
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(match Scc_eio.Cltu.recv flow with
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| Ok frame -> process_tc frame
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| Error `Closed -> ()
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| Error (`Transport e) -> log_error e);
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(* Send ASM-framed TM *)
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Scc_eio.Asm.send flow tm_frame
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let serve ~source ~sink ~process_tc tm_frame =
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(* Receive CLTU-framed TC from a raw byte stream. *)
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(match Scc_eio.Cltu.recv source with
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| Ok frame -> process_tc frame
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| Error `Closed -> ()
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| Error (`Transport _) -> Fmt.epr "transport error@."
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| Error (`Error msg) -> Fmt.epr "decode error: %s@." msg);
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(* Send ASM-framed TM. *)
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match Scc_eio.Asm.send sink tm_frame with
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| Ok () -> ()
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| Error (`Error msg) -> Fmt.epr "send error: %s@." msg
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```