Files
psxrecomp/tools/decode_evcb.py
Matthew Stanley 5b3c7dd08d phase4: freeze_check diagnostic + accumulated overnight infra
Today's session work
- runtime/src/debug_server.c: freeze_check TCP cmd snapshots all liveness
  counters (PC, exception entries, exception_reentry_blocks, dirty_ram
  blocks/insns, fn_entry total + top-K histogram, SIO IRQ pending +
  countdown, sio_stat/i_stat/i_mask, mc_max_state) for tight-loop
  diagnosis when the runtime hangs
- runtime/src/debug_server.c: wtrace slot 12 covering [0x72F0..0x72F4]
  (data-byte counter); measured peak=1 confirming setup_data_phase resets
  the counter mid-cycle
- runtime/src/interrupts.c: exception_entries_total + exception_reentry_blocks
  counters + psx_get_freeze_diag accessor
- runtime/src/sio.c: sio_get_freeze_diag accessor for IRQ pacing internals
- memory entries: phase4_card_gate_setup_writes_2026_04_28 (refutes the
  prior \"missing [0x7568+slot] clearer\" framing — setup functions write
  LSB=0 directly), phase4_72f0_one_byte_per_vblank_2026_04_28 (peak=1
  measurement)

Overnight session work bundled in
- runtime/src/dirty_ram_interp.{c,h}: small MIPS interpreter for
  install-at-runtime kernel RAM stubs (Rule 18; e.g., SIO data-byte
  handler the BIOS writes to RAM 0xCF0)
- recompiler/src/full_function_emitter.{cpp,h}: 3057 jal/jalr continuation
  return labels added to dispatch table (continuation fix); branch
  fall-through fix for conditional-branch delay slots
- recompiler/src/strict_translator.cpp: matching translator updates
- generated/: regenerated SCPH1001 dispatch + full C output reflecting
  the recompiler changes
- runtime/include/debug_server.h, src/memory.c: card_txn ring + SIO IRQ
  ring + EvCB walk ring + per-PC dirty_ram counters + always-on wtrace
  coverage for [0x755A], [0x7514], [0x7528], [0x7520], [0x74A4],
  [0x75C0..C8], [0x74B8..C0]
- recompiler/tests/, runtime/tests/: SIO/card protocol unit tests
- tools/: 60+ Python diagnostic scripts (chain_trace analysis, SIO trace
  diff, EvCB walker, wtrace dumpers, etc.)
- docs/: psx_bios_disasm reference + dynamic_handler_install rationale
- OVERNIGHT_2026_04_28.md, SUMMARY_20260412_2.md: session logs

Phase 4 status (still blocked, root cause better understood)
- BIOS card chain runs through R-handlers correctly (chain_trace shows
  R1..R11 cycling 26x); shell IS retriggering _card_read
- Install handler at ROM 0xBFC15F1C increments [0x72F0] correctly per
  SIO IRQ; gate at <0x80 / <0x7F is correct
- Bottleneck: SIO IRQ countdown is access-paced, fires ~1× per VBlank
  vs ~128× needed; setup_data_phase (called from outer coord on VBlank)
  zeroes [0x72F0] before counter reaches 128
- Both attempted fixes today caused freezes:
  * VBlank deferral on [0x75C0]==1 — pending VBlank already in i_stat
    delivered anyway; tighter dispatch gate also locked up
  * Cycle-paced sio_tick at rates 50, 200 (and gated on [0x75C0]==1) —
    runtime freezes once data phase activates, root cause unidentified
- delay=5 narrows the threshold (peak=2 vs peak=1, no freeze) but
  doesn't get to 0x80
- Real fix likely requires deeper instrumentation of the freeze (call
  stack / dispatch state at the moment of TCP starvation)

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
2026-04-28 21:29:19 -07:00

34 lines
1.2 KiB
Python

#!/usr/bin/env python3
"""Decode EvCB array dump."""
import json, sys
path = sys.argv[1] if len(sys.argv) > 1 else 'evcb_dump.json'
with open(path) as f:
d = json.loads(f.read())
hex_str = d['hex']
data = bytes.fromhex(hex_str)
base = int(d['addr'], 16)
# EvCB stride hypotheses
for stride in (28, 32, 24, 16, 20):
print(f"\n=== Stride {stride} ===")
# head was 0xa000e004 = base + 0x04
arr_start = base + 0x04
found = False
for i in range(40):
off = (arr_start - base) + i * stride
if off + stride > len(data):
break
e = data[off:off+stride]
# Look at first 2 words
cls = int.from_bytes(e[0:4], 'little')
sta = int.from_bytes(e[4:8], 'little')
sp = int.from_bytes(e[8:12], 'little') if stride >= 12 else 0
mo = int.from_bytes(e[12:16], 'little') if stride >= 16 else 0
# Print interesting (class != 0 or status != 0)
if cls or sta:
print(f" slot {i:3d} @0x{base+off:05X}: class=0x{cls:08X} status=0x{sta:08X} spec=0x{sp:08X} mode=0x{mo:08X}")
if cls == 0xF4000001:
found = True
if found:
print(" ^^^ Found 0xF4000001 entries with this stride")