fix: carry pcsx2 companions under the names it opens

emulators/pcsx2-legacy.yml

@@ -78,7 +78,7 @@ files:
     note: "Any file in the BIOS folder whose romdir holds RESET and ROMVER is accepted, whatever its name or size. Naming convention ps2-VVVVr-YYYYMMDD.bin carries version, region and date."
     source_ref: "pcsx2/ps2/BiosTools.cpp:261-323, pcsx2/ps2/BiosTools.cpp:74-167"
 
-  - name: rom1.bin
+  - name: ps2-0230a-20080220.rom1
     system: sony-playstation-2
     required: false
     max_size: 262144
@@ -86,7 +86,7 @@ files:
     note: "Tried as {bios}.rom1 then {biosbase}.rom1. Read into the 256 KB ROM1 region and truncated to it. Logged and skipped when absent."
     source_ref: "pcsx2/ps2/BiosTools.cpp:190-229, pcsx2/ps2/BiosTools.cpp:298, pcsx2/MemoryTypes.h:22"
 
-  - name: ROM2.BIN
+  - name: ps2-0230a-20080220.rom2
     system: sony-playstation-2
     required: false
     max_size: 524288
@@ -94,7 +94,7 @@ files:
     note: "Tried as {bios}.rom2 then {biosbase}.rom2. Read into the 512 KB ROM2 region and truncated to it. Present on Chinese region consoles."
     source_ref: "pcsx2/ps2/BiosTools.cpp:190-229, pcsx2/ps2/BiosTools.cpp:299, pcsx2/MemoryTypes.h:23"
 
-  - name: EROM.BIN
+  - name: ps2-0230a-20080220.erom
     system: sony-playstation-2
     required: false
     max_size: 1835008
@@ -102,6 +102,24 @@ files:
     note: "Tried as {bios}.erom then {biosbase}.erom. Read into the 1.75 MB EROM region and truncated to it."
     source_ref: "pcsx2/ps2/BiosTools.cpp:190-229, pcsx2/ps2/BiosTools.cpp:300, pcsx2/MemoryTypes.h:24"
 
+  - name: ps2-0230a-20080220.nvm
+    system: sony-playstation-2
+    required: false
+    hle_fallback: true
+    min_size: 1024
+    description: "Console NVRAM"
+    note: "Read at the BIOS path with the extension set to nvm. A substitute is written when the file is shorter than 1024 bytes."
+    source_ref: "pcsx2/CDVD/CDVD.cpp:138-149"
+
+  - name: ps2-0230a-20080220.mec
+    system: sony-playstation-2
+    required: false
+    hle_fallback: true
+    size: 4
+    description: "Mechacon version"
+    note: "Read at the BIOS path with the extension set to mec. A 4-byte substitute (03 06 02 00) is written when the file is shorter."
+    source_ref: "pcsx2/CDVD/CDVD.cpp:93-122"
+
   - name: eeprom.dat
     system: sony-playstation-2
     required: false

emulators/pcsx2.yml

@@ -15,7 +15,7 @@ systems: [sony-playstation-2]
 notes: |
   Filename-agnostic BIOS detection. Scans bios/ for any file between 4-8 MB
   with valid romdir structure (RESET + ROMVER entries). No hash validation.
-  Companion files (.rom1, .rom2, .nvm, .mec) derive paths from selected BIOS.
+  Companion files (.rom1, .rom2, .nvm, .mec) derive their names from the selected BIOS.
   ROM1 (DVD player) and ROM2 (Chinese extension) silently skipped if missing.
   NVM and MEC auto-created with defaults if missing.
 
@@ -28,23 +28,35 @@ files:
     source_ref: "pcsx2/ps2/BiosTools.cpp:258-362"
     note: "Accepts any file 4-8 MB with valid romdir (RESET + ROMVER). Naming convention ps2-VVVVr-YYYYMMDD.bin (version, region, date)."
 
-  - name: rom1.bin
+  - name: ps2-0230a-20080220.rom1
     required: false
     max_size: 4194304
-    source_ref: "pcsx2/ps2/BiosTools.cpp:214-241,366"
-    note: "DVD player ROM. Tries {biospath}.rom1 then {biosbase}.rom1. Silently skipped if missing."
+    description: "DVD player ROM"
+    note: "Tried as {bios}.rom1 then {biosbase}.rom1, opened case-insensitively. Copied to the ROM1 region. Logged and skipped when absent."
+    source_ref: "pcsx2/ps2/BiosTools.cpp:214-241, pcsx2/ps2/BiosTools.cpp:366"
 
-  - name: ROM2.BIN
+  - name: ps2-0230a-20080220.rom2
     required: false
     max_size: 4194304
-    source_ref: "pcsx2/ps2/BiosTools.cpp:214-241,367"
-    note: "Chinese ROM extension. Same naming convention as rom1. Only present on Chinese region consoles."
+    description: "Chinese ROM extension"
+    note: "Same two-step naming as rom1. Only Chinese region consoles carry one."
+    source_ref: "pcsx2/ps2/BiosTools.cpp:214-241, pcsx2/ps2/BiosTools.cpp:367"
 
-  - name: EROM.BIN
+  - name: ps2-0230a-20080220.nvm
     required: false
-    source_ref: "pcsx2/ps2/BiosTools.cpp"
-    note: "Extended ROM. Present in some BIOS dumps but not loaded by PCSX2 code via LoadExtraRom."
-    path: null
+    hle_fallback: true
+    size: 1024
+    description: "Console NVRAM"
+    note: "Read at the BIOS path with the extension replaced by nvm, opened case-insensitively. Built in memory from region defaults when absent or blank."
+    source_ref: "pcsx2/CDVD/CDVD.cpp:160-188"
+
+  - name: ps2-0230a-20080220.mec
+    required: false
+    hle_fallback: true
+    size: 4
+    description: "Mechacon version"
+    note: "Read at the BIOS path with the extension replaced by mec. Defaults to 0x00020603 and is written back when it cannot be read."
+    source_ref: "pcsx2/CDVD/CDVD.cpp:190-204"
 
   - name: eeprom.dat
     required: false

scripts/packextras.py

@@ -266,9 +266,68 @@ def _agnostic_scan_extras(
                         "agnostic_scan": True,
                     }
                 )
+                for companion_sha1, companion in _companions(
+                    path, scan_name, _companion_extensions(profile, fname), files_db
+                ):
+                    companion_dest = f"{folder}/{companion['name']}" if folder else companion["name"]
+                    companion_full = (
+                        f"{extras_prefix}/{companion_dest}" if extras_prefix else companion_dest
+                    )
+                    if companion_full in seen_dests:
+                        continue
+                    seen_dests.add(companion_full)
+                    extras.append({
+                        "name": companion["name"],
+                        "destination": companion_dest,
+                        "sha1": companion_sha1,
+                        "required": False,
+                        "hle_fallback": False,
+                        "source_emulator": profile.get("emulator", emu_name),
+                        "source_profile": emu_name,
+                        "source_system": f.get("system"),
+                        "source_systems": list(profile.get("systems", [])),
+                        "region": f.get("region"),
+                        "variant_group": f.get("variant_group"),
+                        "agnostic_scan": True,
+                    })
     return extras
 
 
+def _companion_extensions(profile: dict, seed_name: str) -> set[str]:
+    """Extensions the profile declares beside a free-named BIOS entry.
+
+    PCSX2 reads `<bios>.rom1` or the BIOS path with its extension replaced
+    (`<stem>.rom1`), and likewise nvm and mec (BiosTools.cpp:214-229,
+    CDVD.cpp:160-195). A profile states that by naming the companions after
+    its BIOS entry: ps2-0230a-20080220.rom1 beside ps2-0230a-20080220.bin.
+    """
+    stem = seed_name.rsplit(".", 1)[0].lower()
+    exts: set[str] = set()
+    for entry in profile.get("files", []):
+        other = str(entry.get("name", "")).lower()
+        if other != seed_name.lower() and other.startswith(stem + "."):
+            exts.add(other[len(stem) + 1:])
+    return exts
+
+
+def _companions(
+    image_path: str, image_name: str, extensions: set[str], files_db: dict
+) -> list[tuple[str, dict]]:
+    """Files beside a scanned image that the core opens as its companions."""
+    if not extensions:
+        return []
+    directory = image_path.rsplit("/", 1)[0] + "/"
+    stem = image_name.rsplit(".", 1)[0].lower()
+    wanted = {f"{image_name.lower()}.{ext}" for ext in extensions}
+    wanted |= {f"{stem}.{ext}" for ext in extensions}
+    return sorted(
+        (sha1, entry)
+        for sha1, entry in files_db.items()
+        if entry.get("path", "").rsplit("/", 1)[0] + "/" == directory
+        and str(entry.get("name", "")).lower() in wanted
+    )
+
+
 def _archive_prefix_extras(
     profiles: dict,
     relevant: set,

tests/test_bios_companions.py

@@ -0,0 +1,56 @@
+"""Companions travel with the BIOS image they belong to.
+
+PCSX2 opens <bios>.rom1 or <stem>.rom1, and nvm and mec the same way. Its
+profile named them rom1.bin, ROM2.BIN and EROM.BIN, names the code never
+opens; ROM2.BIN found a misfiled Galaksija ROM inside the PS2 folder, and a
+4 MB size bound then swept GameIndex.yaml and cheat archives to the root of
+the Batocera BIOS folder.
+"""
+
+from __future__ import annotations
+
+import sys
+import unittest
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[1]
+sys.path.insert(0, str(REPO_ROOT / "scripts"))
+
+from packextras import _companion_extensions, _companions  # noqa: E402
+
+
+class Companions(unittest.TestCase):
+    PROFILE = {"files": [
+        {"name": "ps2-0230a-20080220.bin"},
+        {"name": "ps2-0230a-20080220.rom1"},
+        {"name": "ps2-0230a-20080220.nvm"},
+        {"name": "GameIndex.yaml"},
+    ]}
+
+    def test_extensions_come_from_entries_named_after_the_bios(self):
+        self.assertEqual(
+            _companion_extensions(self.PROFILE, "ps2-0230a-20080220.bin"), {"rom1", "nvm"}
+        )
+
+    def test_only_files_named_after_the_image_follow_it(self):
+        files_db = {
+            "a": {"path": "bios/PS2/SCPH-70004.ROM1", "name": "SCPH-70004.ROM1"},
+            "b": {"path": "bios/PS2/scph70004.bin.nvm", "name": "scph70004.bin.nvm"},
+            "c": {"path": "bios/PS2/GameIndex.yaml", "name": "GameIndex.yaml"},
+            "d": {"path": "bios/Other/SCPH-70004.ROM1", "name": "SCPH-70004.ROM1"},
+        }
+        found = _companions("bios/PS2/SCPH-70004.BIN", "SCPH-70004.BIN", {"rom1", "nvm"}, files_db)
+        self.assertEqual([sha for sha, _ in found], ["a"])
+
+    def test_pcsx2_profiles_name_no_free_standing_companion(self):
+        import yaml
+
+        for name in ("pcsx2", "pcsx2-legacy"):
+            profile = yaml.safe_load((REPO_ROOT / "emulators" / f"{name}.yml").read_text())
+            names = {str(f.get("name", "")).lower() for f in profile.get("files", [])}
+            with self.subTest(profile=name):
+                self.assertFalse({"rom1.bin", "rom2.bin", "erom.bin"} & names)
+
+
+if __name__ == "__main__":
+    unittest.main()