Linear Feedback Shift Registers for OCaml
feat(ocaml-globe): zoom-to, hover highlight, click interaction
Scene interaction:
- zoom_to_satellite: smooth camera animation to satellite position
- zoom_to_position: smooth animation to any globe point
- click: pick + auto-zoom in one call
- update_hover: track hovered satellite from mouse position
- hovered: query current hover state
- Hovered satellite drawn with larger dot (14px vs 8px)
Scene stores last_frame for hover/click without needing frame param.
92 tests passing.
+55
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test/test_lfsr.ml
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test/test_lfsr.ml
···
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Alcotest.fail (Printf.sprintf "state became zero at step %d" i)
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done
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(* {1 CCSDS TM frame randomizer test vectors}
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From CCSDS 131.0-B-4 Section 9: TM Synchronization and Channel Coding.
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Polynomial: x^8 + x^7 + x^5 + x^3 + 1, seed = 0xFF, 8-bit LFSR.
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First 32 bytes of the pseudo-random sequence:
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FF 48 0E C0 9A 0D 70 BC 8E 2C 93 AD A7 B7 46 CE
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5A 97 7D CC 32 A2 BF 3E 0A 10 F1 88 94 CD EA B1
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The tap mask for x^8+x^7+x^5+x^3+1 in right-shifting Fibonacci form
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depends on convention. We try taps=0xA9 (bits 0,3,5,7). *)
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let ccsds_tm_vector =
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"FF 48 0E C0 9A 0D 70 BC 8E 2C 93 AD A7 B7 46 CE 5A 97 7D CC 32 A2 BF 3E 0A \
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10 F1 88 94 CD EA B1"
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let tm_first_32 () =
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(* Try the tap mask for x^8+x^7+x^5+x^3+1 *)
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let t = Lfsr.v ~taps:0xA9 ~seed:0xFF ~width:8 in
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let got = Lfsr.generate t 32 in
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let expected = bytes_of_hex ccsds_tm_vector in
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Alcotest.(check string)
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"CCSDS TM first 32 bytes" (Bytes.to_string expected) (Bytes.to_string got)
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(* 8-bit maximal LFSR should have period 255 *)
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let period_8bit () =
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let t = Lfsr.v ~taps:0xA9 ~seed:0xFF ~width:8 in
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let initial = Lfsr.state t in
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let t2 = Lfsr.v ~taps:0xA9 ~seed:0xFF ~width:8 in
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for _ = 1 to 255 do
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ignore (Lfsr.step t2)
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done;
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Alcotest.(check int) "period 255 returns to seed" initial (Lfsr.state t2)
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(* Full period uniqueness: all 255 states in one period should be distinct
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(for a maximal LFSR). We check states, not bytes, since byte output
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depends on 8 steps. *)
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let full_period_uniqueness () =
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let t = Lfsr.v ~taps:0xA9 ~seed:0xFF ~width:8 in
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let seen = Hashtbl.create 256 in
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let all_unique = ref true in
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for i = 1 to 255 do
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ignore (Lfsr.step t);
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let s = Lfsr.state t in
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if Hashtbl.mem seen s then begin
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all_unique := false;
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Printf.printf "duplicate state %d at step %d\n" s i
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end;
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Hashtbl.replace seen s true
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done;
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Alcotest.(check bool) "all 255 states unique" true !all_unique
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let suite =
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( "lfsr",
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[
···
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Alcotest.test_case "step range" `Quick step_range;
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Alcotest.test_case "byte range" `Quick byte_range;
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Alcotest.test_case "no zero state" `Quick no_zero_state;
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Alcotest.test_case "ccsds tm first 32" `Quick tm_first_32;
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Alcotest.test_case "8-bit period" `Quick period_8bit;
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Alcotest.test_case "full period uniqueness" `Quick full_period_uniqueness;
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] )