command advance sweep

h8536/emulator/sci.py

@@ -17,6 +17,7 @@ from .constants import (
     SCI_SSR_RDRF,
     SCI_SSR_TDRE,
 )
+from .uart import UartTiming
 
 
 @dataclass
@@ -53,6 +54,8 @@ class SCI1:
     _frame_buffer: bytearray = field(default_factory=bytearray)
     tx_ready_delay: int = 0
     tx_ready_ticks: int = 2
+    clock_hz: int = 10_000_000
+    tx_timing: UartTiming | None = None
     _tx_ready_pending: bool = False
 
     def read(self, address: int) -> int:
@@ -96,7 +99,7 @@ class SCI1:
             if len(self._frame_buffer) == len(HEARTBEAT_FRAME):
                 self.tx_frames.append(bytes(self._frame_buffer))
                 self._frame_buffer.clear()
-        self.tx_ready_delay = max(0, self.tx_ready_ticks)
+        self.tx_ready_delay = self._tx_ready_delay()
         self._tx_ready_pending = True
         self.tx_events.append(SciTxEvent(SCI1_TDR, value, self.scr, self.ssr, emitted))
 
@@ -116,9 +119,22 @@ class SCI1:
     def saw_heartbeat(self) -> bool:
         return HEARTBEAT_FRAME in self.tx_frames
 
-    def tick(self) -> None:
+    def configure_tx_timing(self, timing: UartTiming | None, *, clock_hz: int | None = None) -> None:
+        self.tx_timing = timing
+        if clock_hz is not None:
+            self.clock_hz = max(1, clock_hz)
+
+    def tx_busy(self) -> bool:
+        return self._tx_ready_pending and self.tx_ready_delay > 0
+
+    def tick(self, cycles: int = 1) -> None:
         if self._tx_ready_pending and self.tx_ready_delay:
-            self.tx_ready_delay -= 1
+            self.tx_ready_delay = max(0, self.tx_ready_delay - max(1, cycles))
         if self._tx_ready_pending and self.tx_ready_delay == 0 and not (self.ssr & SCI_SSR_TDRE):
             self.ssr |= SCI_SSR_TDRE
             self._tx_ready_pending = False
+
+    def _tx_ready_delay(self) -> int:
+        if self.tx_timing is None:
+            return max(0, self.tx_ready_ticks)
+        return self.tx_timing.cycles_per_character(self.clock_hz)