first commit

test/protocol.py

@@ -0,0 +1,22 @@
+def sum16(data: bytes) -> int:
+    return sum(data) & 0xFFFF
+
+
+def build_frame(cmd: int, device_id: int, payload: bytes = b"") -> bytes:
+    frame = bytearray()
+    frame += b'\x23\xA9'                  # 帧头
+    frame += b'\x00\x00'                  # 长度占位
+    frame += device_id.to_bytes(4, 'little')
+    frame += bytes([cmd])
+    frame += payload
+
+    length = len(frame) + 2               # 加上校验和
+    frame[2:4] = length.to_bytes(2, 'big')
+
+    s = sum16(frame)
+    frame += s.to_bytes(2, 'big')
+    return bytes(frame)
+
+
+def parse_device_id(frame: bytes) -> int:
+    return int.from_bytes(frame[4:8], 'little')