51 lines
1.5 KiB
Python
51 lines
1.5 KiB
Python
"""Byte-wise cursor utilities for decoding binary ring payloads."""
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from __future__ import annotations
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import struct
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class ByteCursor:
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"""Read primitive values from bytes while tracking offset."""
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def __init__(self, payload: bytes) -> None:
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"""Create cursor at start of payload."""
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self.payload = payload
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self.offset = 0
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def read_u8(self) -> int:
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"""Read unsigned 8-bit integer."""
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value = struct.unpack_from("<B", self.payload, self.offset)[0]
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self.offset += 1
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return value
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def read_u16(self) -> int:
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"""Read unsigned 16-bit integer."""
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value = struct.unpack_from("<H", self.payload, self.offset)[0]
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self.offset += 2
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return value
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def read_u32(self) -> int:
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"""Read unsigned 32-bit integer."""
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value = struct.unpack_from("<I", self.payload, self.offset)[0]
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self.offset += 4
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return value
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def read_u64(self) -> int:
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"""Read unsigned 64-bit integer."""
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value = struct.unpack_from("<Q", self.payload, self.offset)[0]
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self.offset += 8
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return value
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def read_f32(self) -> float:
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"""Read 32-bit float."""
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value = struct.unpack_from("<f", self.payload, self.offset)[0]
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self.offset += 4
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return float(value)
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def read_bytes(self, size: int) -> bytes:
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"""Read raw byte slice of fixed size."""
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data = self.payload[self.offset : self.offset + size]
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self.offset += size
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return data
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