feat(pm3py): transport layer with NG/MIX frame encoding and async serial I/O

tests/test_transport.py

@@ -0,0 +1,59 @@
+import struct
+from pm3py.transport import encode_ng_frame, decode_response_frame, encode_mix_frame
+from pm3py.protocol import Cmd, CMD_PREAMBLE_MAGIC, RESP_PREAMBLE_MAGIC, crc16_a
+
+def test_encode_ng_frame_ping_no_payload():
+    frame = encode_ng_frame(Cmd.PING, b"")
+    # 8 byte preamble + 0 payload + 2 postamble = 10 bytes
+    assert len(frame) == 10
+    magic, length_ng, cmd = struct.unpack_from("<IHH", frame, 0)
+    assert magic == CMD_PREAMBLE_MAGIC
+    assert length_ng & 0x8000  # ng bit set
+    assert (length_ng & 0x7FFF) == 0
+    assert cmd == Cmd.PING
+
+def test_encode_ng_frame_with_payload():
+    payload = bytes(range(32))
+    frame = encode_ng_frame(Cmd.PING, payload)
+    assert len(frame) == 10 + 32
+    _, length_ng, _ = struct.unpack_from("<IHH", frame, 0)
+    assert (length_ng & 0x7FFF) == 32
+    # verify payload in frame
+    assert frame[8:40] == payload
+    # verify CRC
+    crc_expected = crc16_a(frame[:40])
+    crc_actual = struct.unpack_from("<H", frame, 40)[0]
+    assert crc_actual == crc_expected
+
+def test_encode_mix_frame():
+    frame = encode_mix_frame(Cmd.HF_ISO14443A_READER, 0x107, 0, 0, b"")
+    _, length_ng, _ = struct.unpack_from("<IHH", frame, 0)
+    assert not (length_ng & 0x8000)  # ng bit NOT set for MIX
+    assert (length_ng & 0x7FFF) == 24  # 3x uint64 = 24 bytes
+
+def test_decode_response_frame_success():
+    # Build a fake response frame
+    payload = b"\x01\x02\x03\x04"
+    length_ng = len(payload) | 0x8000
+    preamble = struct.pack("<IHbbH", RESP_PREAMBLE_MAGIC, length_ng, 0, 0, Cmd.PING)
+    body = preamble + payload
+    crc = crc16_a(body)
+    postamble = struct.pack("<H", crc)
+    frame = body + postamble
+
+    resp = decode_response_frame(frame)
+    assert resp["cmd"] == Cmd.PING
+    assert resp["status"] == 0
+    assert resp["data"] == payload
+    assert resp["ng"] is True
+
+def test_decode_response_frame_error_status():
+    length_ng = 0 | 0x8000
+    preamble = struct.pack("<IHbbH", RESP_PREAMBLE_MAGIC, length_ng, -4, -1, Cmd.STATUS)
+    crc = crc16_a(preamble)
+    postamble = struct.pack("<H", crc)
+    frame = preamble + postamble
+
+    resp = decode_response_frame(frame)
+    assert resp["status"] == -4  # ETIMEOUT
+    assert resp["data"] == b""