"""probe_physobj_size.py <dump.dmp>
Find density/spacing of CPhysicsObj instances in the dump.
Spec says 90 leaked + many live ones in CObjectMaint's hash.
"""
import struct, sys
from minidump.minidumpfile import MinidumpFile
from collections import Counter


PHYS_VT = 0x007c78ec


def _ei(v):
    if v is None: return 0
    if hasattr(v, 'value'): return int(v.value)
    return int(v)


md = MinidumpFile.parse(sys.argv[1])
reader = md.get_reader().get_buffered_reader()
scan = []
for r in md.memory_info.infos:
    st, ty, pr = _ei(r.State), _ei(r.Type), _ei(r.Protect) & 0xff
    if st != 0x1000 or ty == 0x1000000 or pr not in (0x04, 0x40): continue
    scan.append((r.BaseAddress, r.RegionSize))

addrs = []
for base, size in scan:
    try:
        reader.move(base); buf = reader.read(size)
    except Exception:
        continue
    if not buf: continue
    end = (len(buf) // 4) * 4
    for off in range(0, end - 4, 4):
        if struct.unpack_from("<I", buf, off)[0] == PHYS_VT:
            addrs.append(base + off)

addrs.sort()
print(f"CPhysicsObj instances by vtable signature: {len(addrs)}")

deltas = Counter()
for i in range(1, len(addrs)):
    d = addrs[i] - addrs[i-1]
    if d < 0x8000:
        deltas[d] += 1

print("top inter-instance deltas:")
for d, n in deltas.most_common(15):
    print(f"  0x{d:04x} ({d:>6})  x{n}")