James Dansereau
d7b9371afb
Public-copy language pass, homepage restructure and Documentation rename, 404 page, dead-anchor and permalink fixes, release-gate sign-off, and the pre-release review fixes of the 2026-10-05 batch (probe-doc drift, build-path hygiene, verify.sh and capture safety). Refs: D533 D534
3.8 KiB
title: Fidelity status description: How faithfully the port reproduces the N64 game: unmodified decompiled logic, Makefile-mirrored region macros, one game-logic-adjacent change, and PRNG notes. date: '2026-10-05' modified_time: '2026-10-05'
Fidelity status
This page answers one question plainly: how faithfully does the port actually reproduce the original N64 game's logic? The audit was run end-to-end on 2026-09-15 and re-verified for the v0.3.0 release bundles on 2026-09-18.
v0.5.0 update pass, 2026-10-05: two of the checks were re-run
directly against the current tree — the region build macros were
compared line-by-line against the original N64 Makefile's macro sets
(all three regions match exactly), and the library file classification
(which original files compile versus get PC-shimmed) was re-checked
against the project's own ground-truth manifest (the CMake build
compiles the libultra and libultrare audio sets, the gu matrix helpers,
and io/vitbl.c only — no silent gaps, no silent duplicates). The
full game-logic audit was not re-run in this pass; recent src/game
edits on the release branch are finding-gated (for example the D519
front-end options work, and a model-c scripted-camera clamp removal
that returned those files to pure decompilation). The full engineering
record behind each item is in the project's finding log
(docs/dev/findings.md).
The rule and what was checked
The port's non-negotiable rule is that decompiled game logic is never
changed — only genuine N64-hardware dependencies get a PC-side
replacement, in the port/ layer. This was audited directly:
- Region build macros exactly mirror the original N64 Makefile's macro sets for all three regions — verified line-by-line (re-run 2026-10-05).
- The audio/library file classification (which original files compile vs. get PC-shimmed) exactly matches the project's own ground-truth manifest — no silent gaps, no silent duplicates (re-run 2026-10-05).
- The one shipped game-logic-adjacent change (a portal-culling
float-precision fix, D271) is
#ifdef PORT-gated, documented in the finding log, and moves toward matching N64 behavior, not away from it. Every other deviation from the decompiled source is one of the documented 32→64-bit pointer-width ABI corrections described above.
One issue, found and fixed before v0.3.0 shipped
The port's random-number generator (port/src/random.c) was documented
as a bit-exact port of the N64's PRNG, but wasn't — a shift-operation
helper didn't match the real MIPS64 instruction semantics it was meant to
mirror. This was independently confirmed by hand-tracing the assembly
against the C port, tracked as finding D284, and fixed before the release
(verified clean across a full level sweep — all 20 missions plus the
ending sequence — no crashes). It affected loot placement, AI behavior
variance, and replay-state determinism from the very first random draw,
in every release before v0.3.0. Because of the fix, RNG-derived output —
including the save-file CRC — changed, which meant existing save files
and any previously recorded replays no longer validate; v0.3.0's release
notes describe the automatic save migration that handles this. We'd
rather say this plainly than let a "verified bit-exact" claim stand
uncorrected, both when it was wrong and now that it's fixed.
Everything else checked (the documented ABI/pointer-width exceptions used for the 32-to-64-bit transition, a sample of the finding log's own claimed fixes against the actual current code) matched what's documented.
This page is kept current alongside future releases. Its source review is a manual, human-reviewed process today — see the project roadmap for plans to partially automate the mechanical parts of it.