ampl parser

tests/test_sweep_reader.py

@@ -66,6 +66,17 @@ def _pack_tty_point(step: int, ch1: int, ch2: int) -> bytes:
     )
 
 
+def _pack_logdet_point(step: int, value: int) -> bytes:
+    return b"".join(
+        [
+            _u16le(0x001A),
+            _u16le(step),
+            _u16le(value),
+            _u16le(0x0000),
+        ]
+    )
+
+
 def _chunk_bytes(data: bytes, size: int = 4096) -> list[bytes]:
     return [data[idx : idx + size] for idx in range(0, len(data), size)]
 
@@ -178,6 +189,26 @@ class SweepReaderTests(unittest.TestCase):
             reader.join(timeout=1.0)
             stack.close()
 
+    def test_parser_16_bit_x2_falls_back_to_logdet_1a00_stream(self):
+        payload = bytearray()
+        while len(payload) < (_PARSER_16_BIT_X2_PROBE_BYTES + 24):
+            payload += _pack_logdet_point(1, 0x0F77)
+            payload += _pack_logdet_point(2, 0x0FCB)
+            payload += _pack_logdet_point(1, 0x0F88)
+
+        stack, reader, queue, stop_event, stderr = self._start_reader(bytes(payload), parser_16_bit_x2=True)
+        try:
+            sweep, info, aux = queue.get(timeout=2.0)
+            self.assertEqual(info["signal_kind"], "bin_logdet")
+            self.assertIsNone(aux)
+            self.assertGreaterEqual(sweep.shape[0], 3)
+            self.assertAlmostEqual(float(sweep[1]), 3959.0, places=6)
+            self.assertIn("fallback -> legacy", stderr.getvalue())
+        finally:
+            stop_event.set()
+            reader.join(timeout=1.0)
+            stack.close()
+
     def test_parser_16_bit_x2_probe_inconclusive_logs_hint(self):
         payload = b"\x00" * (_PARSER_16_BIT_X2_PROBE_BYTES + 128)