The engine synthesized an eglSwapBuffers on each detected frame boundary.
That duplicated the present Android's GLSurfaceView already performs after
every onDrawFrame return, so every frame reached the screen twice - the
second time from a buffer still holding the PREVIOUS frame.
The whole mechanism rested on a premise recorded 2026-09-18 and never
verified live: that nativeOnResume runs the guest's persistent loop on the
GLThread and never returns, leaving the framework unable to present. An
entry/exit counter added to GameRenderer.onDrawFrame shows that is false -
it returns every frame (entries=698 exits=697, the gap being the call in
flight). Rates match 1:1:
synthetic swaps 12.98/s (SWAPMARK, one line per swap)
onDrawFrame 12.69/s (so the framework swapped 12.69/s too)
The user saw this as the car jumping forward then back along its path.
Frame-by-frame the race clock stepped 1:10.06 -> 1:10.03 -> 1:10.09 ->
1:10.06, with presents arriving in pairs 10-20ms apart at a 218ms period -
exactly the synthetic swap period.
Letting the framework present is also what the real game does: libapp.so
cannot present at all (only EGL import is eglGetProcAddress; the string
"eglSwapBuffers" is absent from the binary), and on the A9 all 2,736
eglSwapBuffers calls in 46s came from Android's own framework.
Measured after, on the Pixel 6a:
frame interval median 89ms -> 17ms
p90 217ms -> 19ms
max 316ms -> 24ms
synthetic swaps 0 (verified, not merely absent from view)
onDrawFrame 12.69 -> 12.39/s (throughput deliberately unchanged)
User verdict: "Сейчас очень плавно". Throughput is untouched - this fixes
presentation, not the ~7x simulation deficit.
Kept behind kSynthesizeSwap rather than deleted: the 2026-09-18 symptom it
was built for (screen cycling between stale loading screen, black, and the
real scene) was diagnosed under the false premise above, so its actual
cause is still open.
Co-Authored-By: Claude <noreply@anthropic.com>
Verified live on a Pixel 6a: the game passes its EULA, loads the prologue
and renders real 3D gameplay, with zero heap exhaustion, zero faults and
zero rejected frees over a full session.
Root causes fixed in this state, each backed by a measurement (details and
the list of refuted theories live in ARM64_TRANSLATION_LAYER.md):
* JNI varargs float->double promotion. C promotes float to double in any
varargs call and every Call*Method form is varargs, so reading one 4-byte
slot yielded the double's always-zero low half. EVERY float argument
passed to Java was silently becoming 0; text was just where it showed.
* GuestHeap ~4x memory overhead. Power-of-two size classes carving the full
class, plus segregated free lists that could never share memory between
sizes. Reworked to exact sizing with O(log n) best-fit reuse and splitting
(deliberately not a linear scan - this allocator already had an O(n) perf
cliff in its history). Peak live now 207MB against the real A9's 199MB,
fragmentation ~2.5MB. Also fixed: realloc reading past the old block on
shrink, a 32-bit overflow in calloc, and drifting payload alignment.
* Unbounded FMOD fake-handle leak into the never-freeing permanent arena,
which is why enlarging that arena had not helped.
* Frame presentation, corrected against A9 ground truth: the real frame has
three default-framebuffer colour clears and ONE present at the end; this
engine had been presenting on each of them.
Load-time acceleration (zlib_accel.cpp): host zlib now serves inflate and
crc32, the latter measured by the block profiler as the single hottest guest
routine at 17.7%. Streams are only taken over when this layer saw their own
inflateInit2_, so unknown streams (libpng's, among others) still run the
original emulated path.
name_lookup_accel.cpp is present but its hook is NOT registered - it crashed
on bad assumptions about guest table lifetime and is kept as a starting
point, with both mistakes recorded in its comments.
Co-Authored-By: Claude <noreply@anthropic.com>
Fixes the synthetic car_select jump for cold sessions, makes the loadout
exit chain safe for real (non-synthetic) events, and adds a native->Kotlin
GameEvents bridge (onMapLoaded/onRaceStarted/onRaceEnded/onUpgradesAccepted/
onCarSelected) so both the UI layer and a future native RatNet client can
learn what the player picked - car id, accepted upgrades, and paint color
(name + RGBA) are all resolved live from the game's own engine state
rather than a static extracted table, so they stay correct for any car
added later. Includes a Jetpack Compose overlay as a worked example of a
UI-side GameEventListener consumer.
Full investigation history, root causes, and the several dead ends ruled
out along the way are documented in PROGRESS.md (cont. 30-63b).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
megboyzzandClaude