93 lines
2.2 KiB
Python
93 lines
2.2 KiB
Python
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import struct, warnings
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try:
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import lz4
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except ImportError:
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lz4 = None
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else:
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import lz4.block
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# old scheme for VERSION < 0.9 otherwise use lz4.block
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def decompress(data):
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(compression,) = struct.unpack(">L", data[4:8])
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scheme = compression >> 27
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size = compression & 0x07FFFFFF
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if scheme == 0:
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pass
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elif scheme == 1 and lz4:
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res = lz4.block.decompress(struct.pack("<L", size) + data[8:])
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if len(res) != size:
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warnings.warn("Table decompression failed.")
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else:
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data = res
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else:
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warnings.warn("Table is compressed with an unsupported compression scheme")
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return (data, scheme)
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def compress(scheme, data):
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hdr = data[:4] + struct.pack(">L", (scheme << 27) + (len(data) & 0x07FFFFFF))
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if scheme == 0:
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return data
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elif scheme == 1 and lz4:
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res = lz4.block.compress(
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data, mode="high_compression", compression=16, store_size=False
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)
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return hdr + res
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else:
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warnings.warn("Table failed to compress by unsupported compression scheme")
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return data
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def _entries(attrs, sameval):
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ak = 0
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vals = []
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lastv = 0
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for k, v in attrs:
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if len(vals) and (k != ak + 1 or (sameval and v != lastv)):
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yield (ak - len(vals) + 1, len(vals), vals)
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vals = []
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ak = k
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vals.append(v)
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lastv = v
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yield (ak - len(vals) + 1, len(vals), vals)
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def entries(attributes, sameval=False):
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g = _entries(sorted(attributes.items(), key=lambda x: int(x[0])), sameval)
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return g
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def bininfo(num, size=1):
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if num == 0:
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return struct.pack(">4H", 0, 0, 0, 0)
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srange = 1
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select = 0
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while srange <= num:
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srange *= 2
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select += 1
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select -= 1
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srange //= 2
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srange *= size
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shift = num * size - srange
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return struct.pack(">4H", num, srange, select, shift)
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def num2tag(n):
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if n < 0x200000:
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return str(n)
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else:
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return (
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struct.unpack("4s", struct.pack(">L", n))[0].replace(b"\000", b"").decode()
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)
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def tag2num(n):
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try:
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return int(n)
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except ValueError:
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n = (n + " ")[:4]
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return struct.unpack(">L", n.encode("ascii"))[0]
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