mirror of
https://github.com/SK8-ENGINE/skate-3-rust-engine.git
synced 2026-10-26 19:47:44 +00:00
41 lines
1.2 KiB
Python
41 lines
1.2 KiB
Python
from __future__ import annotations
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import struct
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class FormatError(ValueError):
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"""Raised when an owned input is malformed or outside supported bounds."""
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class Reader:
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def __init__(self, data: bytes, label: str = "input"):
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self.data = data
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self.label = label
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def require(self, offset: int, size: int) -> None:
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if offset < 0 or size < 0 or offset > len(self.data) - size:
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raise FormatError(
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f"{self.label}: range {offset:#x}+{size:#x} is outside "
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f"{len(self.data):#x} bytes"
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)
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def bytes(self, offset: int, size: int) -> bytes:
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self.require(offset, size)
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return self.data[offset : offset + size]
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def u8(self, offset: int) -> int:
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self.require(offset, 1)
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return self.data[offset]
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def u16be(self, offset: int) -> int:
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self.require(offset, 2)
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return struct.unpack_from(">H", self.data, offset)[0]
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def u32be(self, offset: int) -> int:
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self.require(offset, 4)
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return struct.unpack_from(">I", self.data, offset)[0]
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def align(value: int, alignment: int) -> int:
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return (value + alignment - 1) & ~(alignment - 1)
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