43 lines
1.2 KiB
Python
43 lines
1.2 KiB
Python
from __future__ import annotations
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from .formatting import h16
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class DecodeError(Exception):
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pass
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class Rom:
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def __init__(self, data: bytes, base: int = 0) -> None:
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self.data = data
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self.base = base
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@property
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def end(self) -> int:
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return self.base + len(self.data)
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def offset(self, address: int) -> int:
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return address - self.base
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def contains(self, address: int, size: int = 1) -> bool:
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off = self.offset(address)
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return 0 <= off and off + size <= len(self.data)
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def u8(self, address: int) -> int:
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if not self.contains(address):
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raise DecodeError(f"address out of ROM: {h16(address)}")
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return self.data[self.offset(address)]
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def u16(self, address: int) -> int:
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if not self.contains(address, 2):
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raise DecodeError(f"word out of ROM: {h16(address)}")
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off = self.offset(address)
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return (self.data[off] << 8) | self.data[off + 1]
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def slice(self, address: int, size: int) -> bytes:
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if not self.contains(address, size):
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raise DecodeError(f"range out of ROM: {h16(address)}+{size}")
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off = self.offset(address)
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return self.data[off : off + size]
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