psxrecomp/docs/config_schema.md

PSXRecomp v4 — config TOML schema

Consumed by:

• psxrecomp-bios.exe and psxrecomp-game.exe (via --config <toml>)
• tools/audit_config.py and the audit tooling that wraps it
• The runtime cmake macro (runtime/runtime.cmake)

Examples:

• bios/SCPH1001.toml — BIOS-only config (no game; psx-runtime targets this)
• ../TombaRecomp/game.toml — game config (tomba-runtime targets this)

How configs combine

A PSXRecomp v4 process always has a BIOS config. It optionally also has a game config. Both are TOML files in this schema:

• bios/SCPH1001.toml (or another BIOS .toml in bios/) — describes the BIOS. Always loaded.
• <game>/game.toml — describes a single game. Loaded ONLY when running that game.

psxrecomp                            # BIOS-only regen (uses default bios.toml)
psxrecomp games/tomba/game.toml      # BIOS + game regen
psx-runtime                          # boots BIOS discless
psx-runtime games/tomba/game.toml    # boots BIOS, then loads game

When both are loaded, keys merge:

• Scalar keys (debug_port, window_title, memcard_dir, ...): game wins if set, inherit from bios.toml otherwise. Shallow override.
• [program] (BIOS) and [game] blocks: NOT merged — they describe different programs. Both are visible to the loader.
• Generated dispatch tables and C output: ADDITIVE. BIOS contributes SCPH1001_*.c; game contributes <exe>_*.c. No address overlap is expected (BIOS lives at RAM 0x500-0x8500 + ROM 0xBFC..., game at 0x80010000+). The cmake macro psxrecomp_v4_add_runtime_target already links both.
• [[audit.regions]] and [[audit.normalize.remap]]: additive — game adds its regions on top of BIOS's.

Top-level blocks

[program]    # in bios.toml; describes the BIOS
[game]       # in game.toml; describes the game
[recompiler]
[runtime]
[audit]

Program / game block

• bios.toml has a [program] block describing the BIOS ROM.
• game.toml has a [game] block describing the game EXE / disc.

These are NOT alternatives; they're complementary. A runtime loading both sees both blocks. The legacy single-file audit loader (tools/audit_config.py) accepts either as the program-info source for backwards compat, but going forward they are the canonical names for their respective files.

Fields

Field	Required for	Description
name	both	display name, e.g. "SCPH1001 BIOS"
id	both	canonical id, e.g. "SCPH-1001" or "SCUS-94236"
rom	bios	path to raw flat binary, relative to project root
exe	game	path to PS-X EXE file, relative to project root
load_address	both	hex string, virtual address of first byte ("0xBFC00000" BIOS, "0x80010000" typical game)
entry_pc	both	hex string, first PC to execute
text_size	both	hex string, size in bytes of the static region. For games this also bounds main-EXE analysis and establishes the overlay floor. A smaller-than-header bound must be verified non-code and 4 KiB aligned.
stack_base	game	hex string, initial $sp value for the game
disc	game (single-disc)	path to .cue, relative to project root
discs	game (multi-disc)	array of .cue paths; disc is sugar for discs = [disc]

Recompiler block

[recompiler]
seeds       = "recompiler/seeds/phase2_ghidra_seeds.json"  # BIOS
seeds       = "seeds/ghidra_funcs.txt"                     # game (note: game seeds aren't json today)
bios_thunks = "seeds/tomba_bios_thunks.txt"                # game-only
out_dir     = "generated"                                  # both
strict      = true                                         # both — currently always true
discovery   = "whole-image"                                # game-only: "whole-image" or "reachable"
out_stem    = "SCPH1001"                                   # optional; overrides the auto-derived stem

[[recompiler.patch]]
id          = "descriptive-policy-name"
address     = "0x80012340"
expected    = "0x24020002"
replacement = "0x24020001"
note        = "Why this game-owned instruction change is required" # optional

Output filenames: <out_dir>/<out_stem>_full.c and <out_dir>/<out_stem>_dispatch.c. If out_stem is omitted, it's derived from the rom/exe file basename with the trailing .BIN or .EXE stripped (Path.stem is NOT used because it mishandles SCUS_942.36).

Game discovery defaults to "whole-image", preserving the existing sweep and pointer-table heuristics. Opt-in "reachable" starts at the executable entry and evidence-backed seed roots, then follows callable direct jal targets. It does not sweep arbitrary bytes for prologues or return-shaped words. Unresolved jalr/indirect targets and unseen callbacks fail closed to runtime interpretation; add an evidence-backed seed (or a dispatch_root seed for a proven nonstandard boundary) when they should be compiled.

When game.text_size is smaller than the PS-X EXE header size, recompilation uses it as a static-analysis bound. The value must be nonzero, instruction- and 4 KiB-aligned, retain entry_pc, and not extend past PS1 RAM. The original EXE is still loaded from the user's disc. A generated config's canonical final-page reservation may be slightly larger than the header; it does not widen analysis.

Each [[recompiler.patch]] replaces one exact 32-bit MIPS word before function discovery, control-flow analysis, and normal translation. It is intended for small, understood game-code changes whose addresses, opcodes, and policy remain in the game repository. The framework does not contain title IDs or title-specific addresses.

• id, address, expected, and replacement are required hex/string fields; note is optional.
• IDs are case-sensitive and unique within one config.
• Addresses must be four-byte aligned and are unique by the PSX 29-bit physical address. Thus 0x00012340, 0x80012340, and 0xA0012340 are aliases of one site and cannot define separate patches.
• Main-EXE generation fails if the word at the target site is not expected. This catches a wrong disc revision or stale patch instead of guessing.
• Captured overlays may place unrelated variants at one virtual address. In overlay mode, a patch is applied only to a variant whose word is expected; a nonmatching variant is translated unchanged.
• When --config and --ws-config supply the same byte-identical patch it is deduplicated. Reusing an ID or physical address for different patch data is an error.

Patches are build-time inputs, not runtime memory writes or live toggles. Regenerate the affected main executable or captured overlays after changing them.

Runtime block

Consumed by the cmake macro psxrecomp_v4_add_runtime_target (eventually) and by runtime/src/main.cpp as the source of compiled-in defaults.

[runtime]
debug_port    = 4370            # TCP port for the debug server
window_title  = "..."           # SDL window title
controller    = "digital"       # "digital" or "dualshock"
memcard_dir   = "."             # memcard files location, relative to project root

Reserved future fields:

• default_disc_path — game runtimes can pre-mount a disc
• default_game_root — for sibling-junction setups

Audit block

See docs/audit_inventory.md for the audit pipeline. The schema here is the input side: regions to walk, address-normalisation rules.

[audit]
function_starts = "generated/ghidra_function_starts.json"   # optional

[[audit.regions]]
name        = "..."             # e.g. "Boot", "Kernel", "Shell", "Text"
rom_start   = "0x..."           # byte offset in rom/exe file
rom_end     = "0x..."           # exclusive
vaddr_base  = "0x..."           # virtual address corresponding to rom_start

[audit.normalize]
kseg_mask = "0x1FFFFFFF"

[[audit.normalize.remap]]
description = "..."             # human-readable; not consumed by tooling
from_lo     = "0x..."           # inclusive
from_hi     = "0x..."           # exclusive
to_lo       = "0x..."           # target start offset (phys = phys - from_lo + to_lo)

What's NOT in the schema yet (Phase B+)

These are noted here so future work knows where to slot them:

• Game discs field (Phase D). For now Tomba uses disc = "...".
• [runtime] disc_swap_command — runtime-side disc swap (Phase D).
• [recompiler] seeds as an array of paths (currently single file; Phase A might allow multiple).
• [program] type explicit discriminator (currently inferred from rom vs exe field presence).