CCSDS Proximity-1 Space Link Protocol (211.0-B)
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# proximity1
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CCSDS Proximity-1 Space Link Protocol for OCaml.
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Proximity-1 is a short-range data-link protocol for space-to-space
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relay — the classic use case is a Mars orbiter talking to a surface
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rover. `proximity1` encodes and decodes Transfer Frames (a 7-byte
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header plus variable-length data) per CCSDS [211.0-B-5][ccsds], with
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support for Data, Ack, and Expedited frame types.
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[ccsds]: https://public.ccsds.org/Pubs/211x0b5.pdf
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## Installation
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Install with opam:
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<!-- $MDX skip -->
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```sh
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$ opam install proximity1
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```
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If opam cannot find the package, it may not yet be released in the
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public `opam-repository`. Add the overlay repository, then install
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it:
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<!-- $MDX skip -->
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```sh
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$ opam repo add samoht https://tangled.org/gazagnaire.org/opam-overlay.git
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$ opam update
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$ opam install proximity1
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```
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## Usage
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Round-trip a Data frame through the wire format:
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```ocaml
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# let frame =
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{ Proximity1.version = 0;
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scid = 42;
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frame_type = Proximity1.Data;
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sequence_count = 100;
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data = "telemetry" } in
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let wire = Proximity1.encode frame in
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match Proximity1.decode wire with
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| Ok f -> Proximity1.equal f frame
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| Error _ -> false
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- : bool = true
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```
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The header is a fixed 7 bytes:
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```ocaml
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# let frame =
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{ Proximity1.version = 0;
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scid = 1;
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frame_type = Proximity1.Ack;
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sequence_count = 7;
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data = "" } in
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String.length (Proximity1.encode frame) - Proximity1.header_size
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- : int = 0
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```
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`decode` reports a truncated buffer or an unknown frame type
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explicitly, so the caller can distinguish "need more bytes" from
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"unrecognized traffic":
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```ocaml
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# Proximity1.decode "short"
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- : (Proximity1.t, [ `Invalid_frame_type of int | `Truncated ]) result =
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Error `Truncated
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```
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## Licence
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ISC
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