The read stream froze read_delay whenever the guest had an unacked
controller INT (and while the sector buffer was undrained). Real drives
never pause: measured on MMX4's attract/title XA music, the freeze
accumulated ~1M guest cycles/second (~3% of disc time), every XA sector
arrived 32-92 samples late, and the XA->SPU cd_ring starved ~147 samples
5-6x per second — audible as a 6 Hz crackle/dropout flutter in all
XA-streamed music (user report: MMX4 Zero ice-stage attract demo).
Faithful model, mirrored from the in-tree Beetle oracle (cdc.cpp
HandleSectorRead / SetAIP / CheckAIP / ClearAIP):
- Disc time NEVER pauses while reading; sectors are read on exact
cycle schedule. XA-ADPCM realtime audio flows to the SPU decoder
unconditionally (this alone removes the crackle).
- A data sector that comes due while the guest still has an unacked
INT overwrites the sector buffer on schedule (hardware clobbers its
FIFO the same way) and its data-ready INT1 pends ONE deep, presented
the moment the guest fully acks (Beetle CheckAIP). A newer sector
replacing an unpresented notification is counted + traced 'P'
(Beetle "Previous notification skipped").
- Drive-state changes (Read/Play/Pause/Stop/Seek paths through
start/stop_read_stream) cancel the pended notification (ClearAIP).
- The active-DMA refill path (deliver without new INT while a
multi-sector CD DMA drains) is unchanged.
Verification on MMX4 (SLUS-00561) title/attract XA:
- CD_PUSH guest-cycle spacing: exactly 1,806,336 cycles (8 sectors at
2x), min == max over 148 pushes (was 1.83-1.88M, systematically late).
- read_hold_cycles == 0 (was ~30.8M per 30 s) — kept as an always-on
regression tripwire in cdrom_state.
- int1_pended == 0 during music: X4 acks fast; the pending path only
arms for genuinely slow acks.
- spu_out/host tap rings: 6 Hz zero-gap storm (86-144 gaps/95 s of
147-265 samples) eliminated; only real content silences remain.
- cd_underflow_frames stays 0 during playback.
Always-on observability added (ring-buffer doctrine):
- XA zero-run scanner in the decode path -> AUDIO_EV_XA_ZERO events
(stage 0 = post-ADPCM, stage 1 = post-resample+volume, with LBA).
- CD_PUSH audio events now stamp the global guest-cycle clock (the
spu_out sample stamp is pump-quantized and cannot measure cadence).
- cdrom_state: read_hold_cycles/read_hold_events (must stay 0),
int1_pended / int1_lost / int1_pending_now.
- Savestate: pending_dataready fields appended to CDROM_SNAP_FIELDS.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Two hardware-faithfulness fixes found by the always-on tap rings + Beetle
oracle A/B on fingerprint-matched attract music (tools/audio_pair_segments):
the recomp played the identical track at -3.8 dBFS vs the oracle's
-14.1 dBFS — +10.3 dB hot, clipping continuously.
1. spu.c: the voice repeat/loop address register (voice reg 7) is LIVE
state on real hardware — writing it after KEYON retargets where the
next END+REPEAT block jumps (Beetle spu.cpp:1150/333), and the block
auto-latch (flag bit 2) updates the guest-visible register (386/1302).
The recomp cached repeat_addr at KEYON only, so X5's driver idiom —
KEYON, then point the loop register at a silent tail block; no KEYOFF
ever — left voices looping the LOUD sample body forever. Measured: 3
stuck voices re-looping ~1400x/s, 160k SPU events/min vs the oracle's
633, zero game KEYOFF writes (the game never needs one), +11 dB.
2. cdrom.c: implement the CD controller's decode volume matrix
([src][port], 0x80 unity, pending banks + apply latch at 1F801803.3
bit 5 — mapping copied from Beetle cdc.cpp:1483-1501, applied after
the XA resample per PS1 hardware tests). X5 drives it constantly:
0x73-0x7E steady, ramped to 0x00 at scene changes (measured via the
new beetle `cdc_volume` command + PS_CDC::PSXRecomp_GetDecodeVolume
peek). Without it music fades never happened and steady level sat
~0.6 dB hot.
Also: AUDIO_TAP_VOICES (T0 voice-sum tap) for source-by-source mix
decomposition, per-tap WAV rates, bridge stats in audio_stats.
Measured after (MMX5 attract, 20-25 s windows):
spu_out RMS: -3.8 dBFS (clipping) -> -15.5 dBFS [oracle -14.1]
music-only chain already matched the oracle at -14.8 dBFS, confirming
decoder + mixer gain equivalence; the entire excess was stuck voices.
underruns: 2 events / 98 s (delivery fix holding).
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Measurement infrastructure for the audio-quality campaign (MMX5 complaint),
ported from snesrecomp's audio_trace/oracle methodology and the
_audio_round2 tap model. No behavior change to the audio path itself.
- audio_trace.{c,h}: three always-on 95 s PCM rings — T1 spu_out (canonical
spu_render output), T2 cd_in (XA/CD-DA PCM entering the SPU CD bus),
T3 host (exact post-fade bytes handed to SDL_QueueAudio) — plus a 512k
event ring (every SPU reg write stamped with the SPU sample clock;
RENDER/PUMP_SKIP/UNDERRUN/MUTE/UNMUTE/CD_PUSH/SPU-DMA), audible-vs-
silent counters (-42 dBFS gate), queue watermarks, and a server-side
44100 Hz WAV dumper (rate exactness matters: snesrecomp da33c06).
- psx-beetle: the libretro audio callbacks stop discarding Beetle's fully-
mixed reference SPU PCM and record it into the same tap ring. Port 4380
gains audio_stats/audio_wav/audio_events with the identical wire protocol
as the runtime (rule 16 symmetric harness) — the oracle WAV capture.
- debug_server: audio_stats / audio_wav / audio_events on the runtime port.
- tools: audio_ab_diff.py + audio_spectral_ab.py (drift-tolerant offline
A/B: drift ppm, onsets, cents, timbre, click rate) and audio_analyze.py
(first-dirty-tap cross-tap decision tree) ported from snesrecomp/
_audio_round2; audio_capture_ab.py dumps both processes symmetrically.
Probes query history; nothing is armed at probe time.
Extract the runtime's dependency-free RGB->PNG writer into a shared header
(png_write.h, static linkage so each self-contained binary keeps its own copy,
no new link deps). The Beetle debug server's screenshot_file now writes a PNG
(top-down 24bpp RGB) instead of a BMP and defaults its path to .png, matching
the runtime backend — so screenshots are viewer/Read-friendly with no manual
BMP->PNG conversion. Runtime already emitted PNG; this unifies the encoder.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
The Beetle-side fntrace ring recorded only a0/a1; four-argument kernel and
game calls could not be attributed from the oracle side. Capture a2/a3 via
PS_CPU::GetRegister at the trace hook and emit them in fntrace_dump, matching
the native runtime's fntrace field set.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Extends psxrecomp_cdcmd_cb_t (and the beetle_cdcmd_trace ring + cdrom_cmd_dump
JSON) with the guest PC at dispatch, read via PS_CPU::GetRegister(GSREG_PC).
Lets the boot-command-stream oracle-diff localize the first divergent
command's call site (kernel vs shell vs game) instead of only the command
byte — the next step in isolating the early-boot branch divergence behind
Kula World bug 3. Builds clean; behavior-inert when no listener is attached.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BdjxoRB1f9VQsNzZayCgGS
Adds a CD-command trace to psx-beetle (beetle_cdcmd_trace_hook.patch:
callback in cdc.cpp's command dispatch, wired through beetle_libretro.cpp
into cdrom_cmd_dump / cdrom_cmd_reset on the oracle debug server). This is
the two-process oracle-diff the setup is built for, now working on Linux.
Live-diff result (docs/kula-world-findings.md, bug 3): the oracle's game
reads level data with a clean Setloc->SeekL->Setmode->ReadN->Pause per
sector (SeekL x18, ReadN x22, GetlocL x89). Our runtime's game, in the
wedge, issues NEITHER SeekL NOR ReadN — only GetStat/Init/Setloc/Pause,
an error/retry branch the oracle never enters.
Crucial: our runtime DID deliver 307 sectors during early boot (ReadN +
data delivery work). Reads only stop at frame ~890 — the BIOS mid-game
region revalidation (ReadTOC+GetID). The region fix made that PASS, but
the post-ReadTOC CD state still stops the game resuming reads. Prime
suspect: our ReadTOC (case 0x1E) is a bare stat+COMPLETE stub that does
not model drive repositioning / the track table the game reads to
recompute its seek. Documented for the next session.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BdjxoRB1f9VQsNzZayCgGS
Oracle disambiguation (RECURSION_BUG.md §23–§24). Traced one func_8001A954
invocation on real HW (psx-beetle) vs the recomp in the IDENTICAL Tomba idle
state (New Game village dialogue; object 0x801FD950, state/scene/jumptable=0).
VERDICT: real HW's per-frame chain is BALANCED — func_8001A954 is entered once
per frame from main_loop (JAL 0x8001A630, sp=0x801FE3E0) and RETURNS once per
frame (jr ra @0x8001A9E8 -> 0x8001A638, SP fully restored); no re-entry, the
overlay 0x80063864 never calls back (refutes §21/§22's "call-cycle"). The recomp
runs the same guest flow and the guest SP unwinds identically, but the HOST stack
leaks +1.17 KB/frame (ce_profile, live-reconfirmed: 20099->22215 KB / 1807 frames)
because the per-frame compiled chain (func_8001A954->AC00->B2B4->B5A8->func_80046264,
emitted as DIRECT func_X(cpu) host calls) re-enters itself via func_80046264's
CD-DMA-dirty hop and never unwinds.
native_stack early-trip (PSX_STACK_GUARD_KB=6144, frame 7592, 6 MB) pins the
leaking host cycle. Cross-checked: xprobe mixed_depth bounded at 6, dirty-insn/
dirty-block show NO literal func_8001A954 transfer, and a954=1/frame is a SURFACED
guest tail-transfer (j/jr) to func_8001A954 that the oracle proves real HW never
makes — i.e. there is both (A) a correctness divergence (spurious per-frame
re-entry) and (B) the architectural host-mirroring limitation that amplifies it.
Fix scope CORRECTED from §23's "quick contained runtime patch": the UNIVERSAL fix
is §11 — route in-range guest calls through the depth-managed psx_dispatch_impl
trampoline instead of mirroring them as direct host calls, so the host stack stays
bounded regardless of guest re-entrancy (real or fabricated). §12 (CD-DMA dirty
precision) and fixing the specific divergence are surgical mitigations, not
universal. Performance loss accepted for now (static recomp: right before fast).
Instruments added (runtime-only, no regen):
- SP capture in the fntrace control-flow ring on BOTH backends (GPR[29] read live):
psx-beetle (beetle_libretro.cpp + beetle_debug_server.c) and the recomp
(fntrace.h/.c + debug_server.c) — enables the func_8001A954 SP/RA-lifecycle oracle.
- psx-beetle default debug port 4380 -> 4382 (+ --port N override): 4380 collided
with psxref and cdirecomp/CdiRuntime.exe; two LISTENers on one port silently
misroute connections (the phantom "oracle keeps dying" early in the session).
Oracle tooling: the control-flow oracle is psx-beetle (Beetle interprets -> records
every J/JAL/JR/JALR), NOT psxref (no PC trace; the assumed emu_step/emu_trace_addr
never existed). Loads Tomba via: psx-beetle.exe --disc tomba.cue <bios> --port 4382.
Next: implement the §11 universal fix (codegen + full regen).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
- debug_server.c: dump_ram = alias of read_ram (one request, one response,
up to full 2 MB); screenshot = screenshot_file (24-bit BMP, optional
"path", default psx_screenshot.bmp); vram_peek cap 64->128; read_ram hex
encode via nibble table (was 2M snprintf calls stalling the main thread);
send_all_blocking bounded (1 MB chunks, SO_SNDTIMEO 2s, heartbeats the
starvation watchdog per chunk) and drops the client on send failure
instead of letting the watchdog kill the runtime; handle_quit tags exit
origin.
- beetle_debug_server.c: read_ram cap 64 KB->2 MB via heap+send_raw;
dump_ram/screenshot aliases; screenshot w/h->width/height parity;
set_input now holds until clear_input (frames param optional) matching
psx-runtime semantics — the old default expired after 1 frame and the
off-by-one in the getter cleared the override before it was ever read,
so scripted beetle navigation silently did nothing; wtrace_dump response
heap-built + send_raw (per-entry send_fmt dropped chunks on multi-MB
responses, producing broken JSON).
- crash_trace: new psx_crash_trace_set_exit_origin(); report gains
exit_origin (tcp_quit / sdl_window_close / unknown).
- debug_client.py: O(n) string-aware brace parser (old per-byte loop was
O(n^2) — minutes on a 2 MB response, which starved the server's send and
got the runtime killed); generic key=value passthrough for any server
command without a bespoke CLI mapping.
- TCP_COMMANDS.md updated for all of the above.
Verified: 2 MB read_ram round-trip 0.75 s; scripted beetle navigation
reaches the memcard file-select; wtrace_dump returns valid JSON at 21 MB.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Pure observability change — not a fix claim.
Both psx-runtime (was 1) and psx-beetle (was 4) had small accept-
queue backlogs. When the SDL main thread stalls (the exact state
we want to probe during a freeze investigation), the kernel
queues the first pending connect and rejects subsequent attempts
with RST. From the client side this looks like ConnectionRefused,
making it impossible to diagnose the stalled process from another
shell.
Backlog 16 lets a handful of probes queue up. Main thread will
eventually accept them in order if it ever resumes. If the
main thread is permanently dead the probes still fail, but at
least the failure mode changes from "looks like the server is
gone" to "the queue is genuinely deep + still stalled."
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Root cause: BIOS music engine reads voice register 6 (byte offset 0x0C,
CURVOL / ADSR_LEVEL) to find a free voice; recomp returned the never-
written spu_regs value (always 0), so the engine saw every voice as
silent and over-recycled voices 0-3 instead of fanning across all 24.
After fix, recomp KEYON-per-voice counts match Beetle exactly (e.g.
v0 2/2, v18 2/2, v22 1/1).
Also:
- Full ADSR envelope (Attack/Decay/Sustain/Release) ported from Beetle's
CalcVCDelta/RunEnvelope. KEYOFF now triggers Release-phase decay
rather than immediate silencing.
- End-without-loop triggers Release (matches RunDecoder), not active=0.
- ENDX latch at 0x1F801D9C/9E now reports actual block-end-reached
state instead of active-mask.
- SPU event ring (KEYON/KEYOFF/END_STOP/END_LOOP) on both backends with
frame-stamped per-voice payload; 1 M entries each (32 MB) for chime +
game-scene headroom. Beetle-side env>0 filter so silent-loop noise
doesn't bury the audible-voice timeline (matches recomp behavior
where deactivated voices don't fire further events).
- spu_voices / spu_events / spu_events_reset debug-server commands on
both ports. send_fmt buffer kept single-shot to avoid extra newlines.
- tools/_spu_ring_diff.py: frame-aligned event-ring diff with per-voice
count summary; chunk-count cap removed (was aborting reads at 98 KB).
- tools/_spu_capture.py, _spu_probe.py, _probe_one.py: targeted probes
used during diagnosis.
Local-only beetle-psx change (gitignored): same env>0 filter at
mednafen/psx/spu.cpp around line 345/352. Rebuild beetle-psx static
lib if reapplying.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Switches diagnostic methodology from a single binary running both backends
in lockstep (psx-beetleoracle.exe) to two independent processes:
psx-runtime.exe (recomp only, port 4370)
psx-beetle.exe (Beetle libretro only, port 4380)
Both expose the same JSON wire protocol for the common debug commands
(read_ram, press, set_input, clear_input, pad_status, screenshot_file,
wtrace_*, fntrace_* on Beetle). Cross-process comparison is done by
querying both ports from a tool, NOT by sharing input or memory.
Why: the embedded-oracle setup required keyboard input to drive both
backends in lockstep. Once their state diverged, the same keypress
drove them to different screens and "compare on the same press" became
unreliable. Two independent processes lets each backend be navigated
to its own state and queried on its own timeline.
Removed:
- runtime/src/beetle_psx_bridge.cpp (cannibalised into beetle_libretro.cpp)
- runtime/src/duckstation_bridge.cpp
- runtime/src/psx_oracle_cmds.c
- runtime/src/psx_oracle_stub.c
- runtime/include/psx_oracle_backend.h
- psx-beetleoracle and psx-dsoracle cmake targets
- 22 dual-backend tools (emu_read_ram / find_first_divergence / etc)
Added:
- runtime/src/beetle_main.cpp (SDL window + libretro driver + keyboard)
- runtime/src/beetle_libretro.cpp (libretro callbacks + wtrace/fntrace/sio rings)
- runtime/src/beetle_debug_server.c (TCP server, port 4380, same wire protocol)
- psx-beetle cmake target
Also bumps tooling caps surfaced during modal investigation:
- DIRTY_RAM_BLOCK_LOG_CAP: 16K -> 4M (28ms eviction -> ~7s retention)
- WTRACE_MAX_RANGES: 16 -> 64 (boot defaults filled the prior cap)
- DirtyRamBlockLogEntry: added a0/a1 fields for richer dispatch context
CLAUDE.md section 16 rewritten for the new methodology. New memory note
locks the direction so future sessions don't reach for the deleted
embedded-oracle commands.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
Matthew Stanley