command advance sweep

h8536/emulator/uart.py

@@ -7,10 +7,20 @@ from dataclasses import dataclass
 class UartTiming:
     baud: int = 38_400
     data_bits: int = 8
-    parity_bits: int = 0
+    parity: str = "N"
     stop_bits: int = 1
     start_bits: int = 1
 
+    def __post_init__(self) -> None:
+        parity = self.parity.upper()
+        if parity not in {"N", "E", "O"}:
+            raise ValueError("parity must be N, E, or O")
+        object.__setattr__(self, "parity", parity)
+
+    @property
+    def parity_bits(self) -> int:
+        return 0 if self.parity == "N" else 1
+
     @property
     def bits_per_character(self) -> int:
         return self.start_bits + self.data_bits + self.parity_bits + self.stop_bits
@@ -26,10 +36,27 @@ class UartTiming:
 
     def summary(self, clock_hz: int) -> str:
         return (
-            f"uart_{self.data_bits}{'N' if self.parity_bits == 0 else 'P'}{self.stop_bits} "
+            f"uart_{self.data_bits}{self.parity}{self.stop_bits} "
             f"baud={self.baud} byte_us={self.micros_per_character():.3f} "
             f"byte_cycles={self.cycles_per_character(clock_hz)}"
         )
 
+    @classmethod
+    def from_format(cls, text: str, *, baud: int = 38_400) -> "UartTiming":
+        normalized = text.strip().upper()
+        if len(normalized) != 3 or normalized[0] not in "78" or normalized[1] not in "NEO" or normalized[2] not in "12":
+            raise ValueError(f"unsupported UART format {text!r}; expected 8E1, 8N1, 8O1, etc.")
+        return cls(baud=baud, data_bits=int(normalized[0]), parity=normalized[1], stop_bits=int(normalized[2]))
+
+    @classmethod
+    def from_sci_smr(cls, smr: int, *, baud: int = 38_400) -> "UartTiming":
+        data_bits = 7 if smr & 0x40 else 8
+        if smr & 0x20:
+            parity = "O" if smr & 0x10 else "E"
+        else:
+            parity = "N"
+        stop_bits = 2 if smr & 0x08 else 1
+        return cls(baud=baud, data_bits=data_bits, parity=parity, stop_bits=stop_bits)
+
 
 __all__ = ["UartTiming"]