Cool_Tools/bemaniutils
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Add a few more missing bytes, assert where we always see constants.

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This commit is contained in:
Jennifer Taylor 2020-11-09 02:46:36 +00:00
parent d9f96f4b4c
commit f7ffd9185b
1 changed files with 66 additions and 9 deletions
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75
bemani/utils/afputils.py
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@ -53,6 +53,26 @@ def get_until_null(data: bytes, offset: int) -> bytes:
return out
def cap32(val: int) -> int:
return val & 0xFFFFFFFF
def poly(val: int) -> int:
if (val >> 31) & 1 != 0:
return 0x4C11DB7
else:
return 0
def crc32(bytestream: bytes) -> int:
# Janky 6-bit CRC for ascii names in PMAN structures.
result = 0
for byte in bytestream:
for i in range(6):
result = poly(result) ^ cap32((result << 1) | ((byte >> i) & 1))
return result
def descramble_text(text: bytes, obfuscated: bool) -> str:
if len(text):
if obfuscated and (text[0] - 0x20) > 0x7F:
@ -68,12 +88,17 @@ def descramble_text(text: bytes, obfuscated: bool) -> str:
def descramble_pman(package_data: bytes, offset: int, endian: str, obfuscated: bool) -> List[str]:
# Unclear what the first three unknowns are, but the fourth
# looks like it could possibly be two int16s indicating unknown?
magic, _, _, _, numentries, _, data_offset = struct.unpack(
magic, expect_zero, flags1, flags2, numentries, flags3, data_offset = struct.unpack(
f"{endian}4sIIIIII",
package_data[offset:(offset + 28)],
)
add_coverage(offset, 28)
# I have never seen the first unknown be anything other than zero,
# so lets lock that down.
if expect_zero != 0:
raise Exception("Got a non-zero value for expected zero location in PMAN!")
if endian == "<" and magic != b"PMAN":
raise Exception("Invalid magic value in PMAN structure!")
if endian == ">" and magic != b"NAMP":
@ -84,13 +109,12 @@ def descramble_pman(package_data: bytes, offset: int, endian: str, obfuscated: b
# Jump to the offset, parse it out
for i in range(numentries):
file_offset = data_offset + (i * 12)
# Really not sure on the first entry here, it looks
# completely random, so it might be a CRC?
_, entry_no, nameoffset = struct.unpack(
name_crc, entry_no, nameoffset = struct.unpack(
f"{endian}III",
package_data[file_offset:(file_offset + 12)],
)
add_coverage(file_offset, 12)
if nameoffset == 0:
raise Exception("Expected name offset in PMAN data!")
@ -99,6 +123,9 @@ def descramble_pman(package_data: bytes, offset: int, endian: str, obfuscated: b
name = descramble_text(bytedata, obfuscated)
names[entry_no] = name
if name_crc != crc32(name.encode('ascii')):
raise Exception(f"Name CRC failed for {name}")
for i, name in enumerate(names):
if name is None:
raise Exception(f"Didn't get mapping for entry {i + 1}")
@ -237,12 +264,32 @@ def extract(
else:
# Now, see if we can extract this data.
print(f"Writing {filename} texture data...")
magic, _, _, length, width, height, fmtflags = struct.unpack(
f"{endian}4sIIIHHI",
raw_data[0:24],
(
magic,
header_flags1,
header_flags2,
length,
width,
height,
fmtflags,
expected_zero1,
expected_zero2,
) = struct.unpack(
f"{endian}4sIIIHHIII",
raw_data[0:32],
)
if length != len(raw_data):
raise Exception("Invalid texture length!")
# I have only ever observed the following values across two different games.
# Don't want to keep the chunk around so let's assert our assumptions.
if (expected_zero1 | expected_zero2) != 0:
raise Exception("Found unexpected non-zero value in texture header!")
if raw_data[32:44] != b'\0' * 12:
raise Exception("Found unexpected non-zero value in texture header!")
if struct.unpack(f"{endian}I", raw_data[44:48])[0] != 3:
raise Exception("Found unexpected value in texture header!")
if raw_data[48:64] != b'\0' * 16:
raise Exception("Found unexpected non-zero value in texture header!")
fmt = fmtflags & 0xFF
# Extract flags that the game cares about.
@ -655,9 +702,14 @@ def extract(
# I am not sure what the unknown byte is for. It always appears as
# all zeros in all files I've looked at.
_, length, binxrpc_offset = struct.unpack(f"{endian}III", data[offset:(offset + 12)])
expect_zero, length, binxrpc_offset = struct.unpack(f"{endian}III", data[offset:(offset + 12)])
add_coverage(offset, 12)
if expect_zero != 0:
# If we find non-zero versions of this, then that means updating the file is
# potentially unsafe as we could rewrite it incorrectly. So, let's assert!
raise Exception("Expected a zero in font package header!")
if binxrpc_offset != 0:
benc = BinaryEncoding()
fontdata = benc.decode(data[binxrpc_offset:(binxrpc_offset + length)])
@ -697,13 +749,18 @@ def extract(
# First word is always zero, as observed. I am not ENTIRELY sure that
# the second field is length, but it lines up with everything else
# I've observed and seems to make sense.
_, afp_header_length, afp_header = struct.unpack(
expect_zero, afp_header_length, afp_header = struct.unpack(
f"{endian}III",
data[structure_offset:(structure_offset + 12)]
)
add_coverage(structure_offset, 12)
add_coverage(afp_header, afp_header_length)
if expect_zero != 0:
# If we find non-zero versions of this, then that means updating the file is
# potentially unsafe as we could rewrite it incorrectly. So, let's assert!
raise Exception("Expected a zero in font package header!")
# This chunk of data is referred to by name, and then a chunk.
anim_name_offset, anim_afp_data_length, anim_afp_data_offset = struct.unpack(
f"{endian}III",