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Mapping-owned stick precision migration

Status: the shared stick mapper now retains fractional coordinates through profile transforms, directional remapping and final Xbox360/One and Switch2 encoding. This is a source/software-validation milestone, not production or hardware certification. Remaining feature and physical validation gates are listed below and in the controller-platform ledger.

One authoritative mapped value

DS4MappedStickAxis stores a fractional coordinate in the existing profile domain (0..255, center 128). FromSigned retains all 65,536 signed-16 source values; the compatibility byte projection matches the existing Switch2 quantizer. The default value is neutral. NaN, infinity and out-of-range coordinates are rejected. Pro and standalone/joined JoyCon projections seed these axes from their logical, orientation-adjusted calibrated source values.

The four axis fields in DS4State own control state. Existing LX/LY/RX/RY byte properties read a compatibility projection, but every byte assignment replaces precision, including a write of the same byte. State constructor and CopyTo copy the typed axes; CopyExtrasTo never does. Immutable raw source metadata cannot undo a remap, suppression, macro, gyro or OSC override.

This changes public byte fields to properties, removes unused public filter-history implementation fields, and changes DS4StateFieldMapping.axisdirs from a byte array to a readonly typed-store reference. That store retains byte indexer/Length source compatibility, not the complete array API. Rebuild all consumers: assemblies compiled against those old fields are not binary-compatible. No supported repository consumer was found relying on their field/reflection ABI.

PostMapStickData also exposes synchronized compatibility properties in place of fields. Its production submit/reset/consume APIs are authoritative; Mapping.gyroStickX/Y are diagnostic compatibility mirrors, not an injection API. External callers that previously wrote those public implementation arrays must migrate instead of expecting their writes to drive production output.

Migrated operations

  • Rotation uses the same trigonometry and clamp, but retains fractional coordinates when either coupled axis is precise. Legacy-only input retains the old byte truncation.
  • User drift offsets keep the existing integer profile settings and clamp. Precise input retains its fraction; legacy input keeps the old result.
  • Sensitivity and square-stick wrappers use the same existing equations. Sensitivity retains per-axis precision; square-stick promotes both coupled outputs if either input is precise. Center checks use the actual coordinate, not the rounded byte. Every legacy write still truncates at its original stage, including when transforms are chained. The existing square-stick trigonometric core is unchanged.
  • DS4StickProfileTransform contains the existing shared radial/axial deadzone, anti-deadzone, max-zone/output, vertical-scale, outer-binding and output-curve equations. Both sides call it in their original order; radial operations couple precision, while axial operations retain independent ownership. LegacyStickProfileOracle freezes the pre-migration equations and cast sites for exhaustive byte-grid comparisons. The final outer binding remains an intentionally byte-valued binding, computed from the full precise vector.
  • Custom curves capture a compiled immutable continuous evaluator once per coupled pair, not an interpolation of the rounded byte LUT. See continuous-bezier-evaluation.md for solver, fallback and near-flat numerical behavior. Legacy byte LUT behavior remains unchanged; that existing mutable LUT does not provide an atomic profile-edit snapshot across all legacy/precise axes.
  • Field-map population and output own typed values in one backing store. Direction remapping scales precise signed magnitude about center 128 using the asymmetric 128/127 extents. Legacy remapping keeps 255-value. Explicit suppression/None/macro/button byte writes retire the affected precise value.
  • Angle calculation, mapped-stick activation/mouse reads and the three Switch2 stick-scroll/direction/assist lanes use fractional profile coordinates. Neutral OSC input leaves the current axis untouched; explicit OSC input replaces it. Strongest-contributor selection uses the actual coordinate and retains the current owner on ties. Deferred gyro contribution does not own a copy of the prior physical winner, which could otherwise replay after release.
  • Xbox360 and Xbox One use the final mapping-owned signed-16 coordinate, and Switch2 uses the final unsigned-12 coordinate. Legacy byte sources keep the exact historical float/integer converters. Steering overrides retain their final authority. Sony targets still quantize to their actual 8-bit domain. No encoder reads raw source metadata to restore a discarded axis.
  • Anti-snapback uses the existing segment/center-circle geometry and strict history expiry. Fuzz uses the existing radial movement threshold and exact endpoint exceptions. Both operate on typed coordinates and retain typed held values. Fuzz's deliberate suppression is not source quantization.
  • Anti-snapback replaces the allocating LINQ closure and growing queue with a preallocated 8,192-point ring per stick. This accommodates the full 1-second UI window at 8,000 samples/s, including its boundary. Overflow increments a counter and bypasses only anti-snapback decisions while continuing to record fresh samples; decisions resume only after missing history expires. Another overflow extends that boundary. No input event queue is involved.
  • Timeout is clamped to the UI range 0..1000 ms. Invalid/non-finite or out-of-UI delta disables anti-snapback; negative fuzz disables fuzz. This intentionally replaces unchecked malformed-profile behavior. Ordinary valid legacy settings retain the original geometry and threshold decisions.
  • Timing comes from QPC converted to monotonic milliseconds, not wall clock or coarse Environment.TickCount64. No sleep or pacing loop is added.
  • Input and preview pass their actual controller owner. Weak owner identity, profile revision/reset, physical/transport generations, pair/presence/layout and rotation changes fence history. Profile/UI reset requests are atomic; only the input/preview owner mutates its filter history.

Storage is bounded, but worst-case work is still linear in active history. Maximum-window CPU-only observations and allocation tests are not Windows presentation or physical-to-game latency results.

Deferred gyro/touch ownership

The legacy joined Joy-Con path can have two input threads contributing to one slot. An operation captures the accumulator epoch before its profile/activation calculation and validates that same token when publishing. Reset, submit and consume use a dedicated short gate around fixed scalar state. No profile math, callback, controller I/O, logging or allocation is performed while holding it. This synchronization is required by the demonstrated two-writer race, not a pacing mechanism; contention/scheduler-tail latency still requires measurement.

Profile resets, Mouse owner construction/reset, exact slot retirement and reports which skip custom mapping retire pending/current gyro contributions. A delayed producer from the prior epoch cannot be relabeled by a new producer. The immediate joined-gyro merge preserves a stronger physical value but retains only the actual gyro candidate for the next primary report, never a snapshot of that physical winner. Current gyro state is owned by the accumulator; compatibility mirrors cannot bypass admission.

This does not serialize the entire pre-existing legacy joined-controller shared mapped-state presentation path. That separate concurrency and hardware validation gate remains open; Switch2 joined publication has its own existing serialized runtime owner.

Limits and remaining gates

  • Triggers, outer bindings, and generated gyro/touch-stick/OSC byte outputs retain their existing value vocabulary. Expanding a trigger to Xbox ten-bit wire format cannot recover precision it never carried. This work does not claim full-precision analog stick-to-trigger remapping.
  • Flick-stick current/previous source coordinates and right-stick mouse delta-acceleration still read legacy byte input. They do not overwrite the virtual stick coordinate, but full mouse-feature precision parity remains separate work.
  • Per-unit raw travel calibration, controller-operated confirm/cancel profile selection, full source/target/profile integration inventory, BLE/USB device matrix, actual game feedback, latency/soak measurements and installer gates remain open. No sub-millisecond or non-inferiority claim follows from these tests, and no native-driver backend was added.
  • Whole-profile concurrent-edit atomicity and the existing legacy joined controller shared mapped-state presentation path are not established by a typed coordinate alone. Accumulator retirement must be separately fenced; final validation and any remaining concurrency findings belong in the ledger.

The focused tests include all 65,536 signed positions into Xbox wire encoders, all 4,096 calibrated 12-bit positions through identity profile/field mapping into Switch2 wire encoding, frozen legacy byte grids, non-linear/chained production profiles, explicit overrides and warmed allocation assertions. These are not substitutes for the remaining complete feature/hardware matrix.