Adds PCSX-Redux's MIT-licensed OpenBIOS as a second BIOS the framework can
statically recompile, next to retail SCPH1001. Because OpenBIOS is
redistributable, a game verified against it ships its BIOS with the build —
players supply only a disc, and the launcher BIOS picker disappears.
The mechanism is general, not OpenBIOS-specific: every BIOS image gets a
bios/<STEM>.toml profile that is the single source of truth for its identity
and layout.
Recompiler
- bios/<STEM>.toml profiles: [program.image] (sha256 pin, redistributable
flag), [recompiler.address_model] (boot-time ROM->RAM copy windows,
kernel-bless window), install_slots, and [recompiler.runtime_exports]
HLE anchors (0 = feature structurally unavailable on that BIOS).
- BiosAddressModel (new): validated model built from the profile, replacing
~9 hardcoded SCPH1001 window constants that had drifted apart across the
emitter / discovery / game codegen. The emitted C normalize() derives
from the same table. from_config rejects overlapping/misaligned windows
and orderings where sequential folding != first-match. A CTest-registered
equivalence test sweeps every RAM/ROM address against verbatim copies of
the old helpers.
- Orphaned delay slots (the OpenBIOS-critical emitter fixes): jr/jalr
slots are inlined before the jump resolves — previously their side
effect was silently LOST (e.g. a case-return fragment's addiu $sp pop,
which unwound a shifted frame and walked the exception handler's IntRP
cursor into a wild dispatch). Orphaned branches resume at ds+4 on
not-taken instead of re-executing the slot (a read-modify-write slot
doubling twice broke OpenBIOS readPad). Jump targets latch pre-slot.
- MIPS-I load-delay modeling for dependent load pairs: the successor sees
the pre-load value (OpenBIOS's cardfasttrack.s relies on it on purpose —
"gotta break those bad emulators"). Unmodeled shapes warn at build time.
- Discovery hardening: branch-target dispatchability closure to fixpoint;
jump tables placed at jr+8 no longer walked as code; cross-function
continuations routed by an instruction->owner map.
- Signed MULT support (unreachable from the retail seed set; modern-GCC
OpenBIOS emits it freely), latency-modeled like MULTU.
- Seeds from ELF symbol tables + data-section code-pointer harvest
(tools/gen_bios_seeds_from_elf.py) — a source-built BIOS needs no
disassembly pass. 646 OpenBIOS seeds, incl. 5 empirical dispatch-miss
seeds.
- Stemmed outputs (<out_stem>_full.c / _dispatch.c) so two BIOSes coexist
in one out_dir. tools/regen_bios.sh is profile-driven (--config).
Runtime
- psx_bios_image: the generated dispatch now self-describes the BIOS it
was compiled from (identity: size/CRC32/SHA-256/wordsum; kernel-bless
window; HLE anchors; bundled flag). Runtime SCPH1001 hardcodes removed.
- Launch check is a hard identity gate (a mismatched image under
statically recompiled code is a guaranteed wild jump). Bundled builds
hide the BIOS picker and treat a missing/tampered bundled image as an
installation defect.
- Faithfulness fixes surfaced by OpenBIOS's tighter timing loops (all
global, argued in code comments, regression-tested against SCPH1001):
- SIO pad RX is cycle-paced like the memcard path (RX_RDY at
shift-complete, ACK +170); total ack-IRQ latency unchanged.
PSX_SIO_PAD_SYNC_RX=1 restores the legacy synchronous path for A/B.
- SPUSTAT derived from SPUCNT instead of permanently-asserted busy.
- GPUSTAT.13 (interlace field) alternates per vblank while interlaced,
pinned 0 in progressive.
- CD Init(0x0A) completes in ~3.9 ms instead of borrowing Beetle's
34 ms Reset figure (OpenBIOS's short bounded retry loop livelocked).
- Exception EPC guard accepts ROM-window block leaders, not just RAM.
- New TCP debug commands (documented in TCP_COMMANDS.md): bios_info,
s3_smear_watch, callret_watch; write-trace ring gains $s0-$s5.
bios/openbios.bin is vendored (MIT — notice in bios/OpenBIOS.LICENSE,
attribution in THIRD_PARTY_ATTRIBUTION.md, source pin + build recipe in
bios/OpenBIOS.toml). The emitter fingerprint digest is now content-only:
existing generated/*.emitter.sha will read STALE once; re-run
tools/regen_bios.sh.
The BIOS shell code (ROM 0xBFC18000+) runs from RAM at 0x80030000+.
Jump tables in shell functions store RAM-space target addresses, but
at recompile time only the ROM data is available.
Three fixes:
1. function_discovery.cpp: detect jump table pattern (SLTIU/SLL/LUI/
ADDU/LW/JR) during function scanning, translate RAM table addresses
to ROM, push case targets onto BFS work queue so case body code is
included in the function's instruction set.
2. full_function_emitter.cpp: detect same pattern at jr emission time,
read table from ROM with RAM-to-ROM mapping, emit C switch/goto
instead of cpu->pc=reg;return for resolved tables.
3. code_generator.cpp: add ram_to_rom() helper for the existing jump
table detection (used by a different code path).
Result: 13 jump tables resolved across the BIOS, +6 functions discovered,
+2825 instructions included. Dispatch miss at 0x80058564 (memcard SIO
handler) eliminated.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Three interrupt delivery bugs fixed that were blocking shell progression:
1. RFE after handler exit: The exception handler's normal exit path
(jmpbuf longjmp at 0xBFC10944) does not execute RFE. In our model
the handler returns to psx_check_interrupts, not to the WaitEvent
caller. Without RFE, IEc stays 0 forever after the first interrupt.
Fix: apply RFE in psx_check_interrupts if IEc is still 0 after the
handler returns.
2. GPR save/restore around handler dispatch: The handler's jmpbuf exit
restores callee-saved registers from the kernel jmpbuf (intended for
a non-local jump to WaitEvent's caller). In our model this corrupts
the interrupted code's registers. Fix: save all GPRs before handler
dispatch and restore them after, matching real hardware where the
interrupted code's registers are preserved via TCB save/restore.
3. VBlank tick gated on !in_exception: The handler runs thousands of
block leaders, each calling psx_check_interrupts. Without gating,
dispatch_count advances inside the handler, firing new VBlanks that
stack up and starve the main code. Fix: only increment dispatch_count
and fire VBlank/timer ticks when not in exception handling.
4. DMA IRQ edge-triggered: update_master_irq() was level-triggered,
re-asserting i_stat bit 3 on every call while master_flag=1. Combined
with no BIOS callback to acknowledge DMA IRQs, this caused an
interrupt storm. Fix: edge-detect master_flag 0->1 transition, and
suppress DMA completion IRQs entirely since transfers are synchronous.
Also adds GPU debug diagnostics: GP0 command counters (nop/fill/draw/
env/copy), draw area/offset in gpu_state, vram_peek debug command.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Henrique Guedes