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re: widen the OB scan to seven encodings; run inconclusive, probe lacked a witness

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ob_by_hud.py now scans seven readings of the same bytes and keeps a separate
candidate set for each, as byte offsets: u32 big and little endian, u16 both
endiannesses at both alignments, and u8. The big-endian u32 reading had been
refuted, so widening rather than assuming is the point.

u32le is much the tightest at 154 candidates against u32be's 4452. That is a
hint about the encoding rather than a result, since a rarer bit pattern narrows
faster regardless of meaning.

The run is inconclusive. The HUD read 4 at every sample, so there was no second
value to collapse the sets against, and from t=136 the candidate counts are
byte-identical across five samples in all seven encodings, which is what a
frozen guest looks like -- nothing in 32 MB changed at all. The probe had no
stall witness, so the run cannot prove it either way. One is added now.

Worth stating plainly: this is the fourth probe written without a witness and
the third whose flat output could not be distinguished from a freeze. Each time
the fix gets applied to that one script. The durable fix is the shared probe
harness already noted in this file, and the lesson recurring four times is
itself the argument for building it.

What the hunt needs is unchanged: two HUD readings at different values in
non-stalled samples. The counter moves on kills, which lands back on the combat
limit, though the earlier 4 to 11 observation shows it does move.
This commit is contained in:
Sylpheed RE agent
2026-08-24 23:14:59 +00:00
parent 696119b9e6
commit a040cad0da
3 changed files with 117 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files

76
tools/re-capture/ob_by_hud.py
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@@ -24,7 +24,30 @@ def region(fd):
out, pos = bytearray(), lo
while pos < hi:
n = min(1 << 24, hi - pos); out += os.pread(fd, n, pos); pos += n
return np.frombuffer(bytes(out), dtype='>u4'), lo
return bytes(out), lo
# The big-endian u32 reading was refuted: no word held 4 then 11. Widen rather
# than assume -- the counter may be narrower, little-endian, or unaligned. Each
# encoding keeps its own candidate set, expressed as BYTE OFFSETS so the answer
# is directly usable whichever one wins.
ENCODINGS = [
('u32be', '>u4', 4, 0), ('u32le', '<u4', 4, 0),
('u16be', '>u2', 2, 0), ('u16be@1', '>u2', 2, 1),
('u16le', '<u2', 2, 0), ('u16le@1', '<u2', 2, 1),
('u8', 'u1', 1, 0),
]
def matches(buf, value):
"""byte offsets whose value equals `value`, per encoding"""
out = {}
for name, dt, w, skew in ENCODINGS:
if value > (1 << (8 * w)) - 1:
continue
n = (len(buf) - skew) // w * w
a = np.frombuffer(buf[skew:skew + n], dtype=dt)
idx = np.nonzero(a == value)[0]
out[name] = idx.astype(np.int64) * w + skew
return out
def hud_value():
subprocess.run(['screenshot', SHOT], capture_output=True, timeout=60)
@@ -40,6 +63,19 @@ def main():
secs = int(sys.argv[1]) if len(sys.argv) > 1 else 240
every = int(sys.argv[2]) if len(sys.argv) > 2 else 25
w = gworld.World(); fd = w.fd
# Witness. This is the FOURTH probe written without one, and the third to
# produce a run whose flat output could not be distinguished from a freeze.
# The recurring fix is a shared harness; until that exists, carry it.
b0, _ = region(fd); time.sleep(3.0); b1, _ = region(fd)
a0 = np.frombuffer(b0, dtype='>u4').astype(np.int64)
a1 = np.frombuffer(b1, dtype='>u4').astype(np.int64)
d = a1 - a0
rates = collections.Counter((d[(d > 15) & (d < 600)] // 3).tolist())
band = [r for r in rates if 8 <= r <= 40]
pick = max(band, key=lambda r: rates[r]) if band else None
ticks = np.nonzero(d // 3 == pick)[0][:32] if pick is not None else np.array([], dtype=int)
print('tick witnesses: %d at %s/s' % (len(ticks), pick), flush=True)
last_t = a1[ticks] if len(ticks) else None
cand = None; base = None; seen = []
t0 = time.time()
while time.time() - t0 < secs:
@@ -48,23 +84,39 @@ def main():
if v is None:
print(' t=%4ds HUD unreadable (%s)' % (el, note), flush=True)
else:
r, base = region(fd)
hit = set(np.nonzero(r == v)[0].tolist())
cand = hit if cand is None else (cand & hit)
buf, base = region(fd)
hit = matches(buf, v)
if cand is None:
cand = hit
else:
cand = {k: np.intersect1d(cand[k], hit[k], assume_unique=True)
for k in cand if k in hit}
seen.append(v)
print(' t=%4ds HUD=%-4d words==%d: %-8d -> candidates %d (%s)'
% (el, v, v, len(hit), len(cand), note), flush=True)
if len(cand) <= 40 and len(set(seen)) >= 2:
st = ''
if len(ticks):
now_t = np.frombuffer(buf, dtype='>u4').astype(np.int64)[ticks]
if int((now_t > last_t).sum()) == 0: st = ' *** GUEST STALLED ***'
last_t = now_t
print(' t=%4ds HUD=%-4d %s%s (%s)'
% (el, v, ' '.join('%s:%d' % (k, len(cand[k])) for k in cand), st, note),
flush=True)
live = {k: c for k, c in cand.items() if len(c)}
if live and len(set(seen)) >= 2 and min(len(c) for c in live.values()) <= 40:
break
time.sleep(every)
print('\nHUD values seen: %s' % sorted(set(seen)))
if cand and base is not None:
print('candidates: %d' % len(cand))
for i in sorted(cand)[:20]:
va = gmem.primary_va(base + i * 4)
print(' va %s' % (('%#010x' % va) if va else '?'))
for k in sorted(cand, key=lambda k: len(cand[k])):
c = cand[k]
print(' %-8s %d candidate(s)' % (k, len(c)))
for off in c[:8]:
va = gmem.primary_va(base + int(off))
print(' va %s' % (('%#010x' % va) if va else '?'))
if all(len(c) == 0 for c in cand.values()):
print('\nEVERY encoding eliminated -- the counter is not in this region '
'in any of them, or a HUD reading is wrong.')
else:
print('no candidates (HUD never read, or value never matched a u32)')
print('no candidates (HUD never read)')
return 0
if __name__ == '__main__':