UART simulation

tests/test_emulator_rx_probe.py

@@ -1,7 +1,15 @@
 import argparse
 import unittest
 
-from h8536.emulator.rx_probe import frame_checksum, frame_checksum_ok, parse_frame
+from h8536.emulator import H8536Emulator, SCI1_RDR, SCI1_SSR, SCI_SSR_ORER, SCI_SSR_RDRF
+from h8536.emulator.rx_probe import RunContext, UartTiming, _inject_frame_uart_timed, frame_checksum, frame_checksum_ok, parse_frame
+
+
+def rom_with_reset(*, reset: int = 0x1000, size: int = 0x1020) -> bytearray:
+    rom = bytearray([0xFF] * size)
+    rom[0:2] = reset.to_bytes(2, "big")
+    rom[reset : reset + 2] = b"\x20\xFE"  # BRA self
+    return rom
 
 
 class EmulatorRxProbeTest(unittest.TestCase):
@@ -22,6 +30,23 @@ class EmulatorRxProbeTest(unittest.TestCase):
         with self.assertRaises(argparse.ArgumentTypeError):
             parse_frame("04 00 00 40")
 
+    def test_uart_timed_injection_does_not_wait_for_rdrf_consumption(self):
+        emulator = H8536Emulator(bytes(rom_with_reset()), clock_hz=10_000_000)
+        context = RunContext()
+
+        steps, reason = _inject_frame_uart_timed(
+            emulator,
+            b"\x11\x22",
+            timing=UartTiming(baud=38_400),
+            max_steps_per_gap=1000,
+            context=context,
+        )
+
+        self.assertEqual(reason, "frame_injected_uart_timing")
+        self.assertGreater(steps, 0)
+        self.assertEqual(emulator.memory.read8(SCI1_RDR), 0x11)
+        self.assertEqual(emulator.memory.read8(SCI1_SSR) & (SCI_SSR_RDRF | SCI_SSR_ORER), SCI_SSR_RDRF | SCI_SSR_ORER)
+
 
 if __name__ == "__main__":
     unittest.main()

tests/test_emulator_sci_timing.py

@@ -12,6 +12,7 @@ from h8536.emulator import (
     SCI_SSR_RDRF,
     SCI_SSR_TDRE,
     SCI1,
+    UartTiming,
 )
 
 
@@ -66,6 +67,22 @@ class SciTimingTest(unittest.TestCase):
         self.assertEqual(sci.tx_frames, [HEARTBEAT_FRAME])
         self.assertTrue(sci.saw_heartbeat())
 
+    def test_inject_rx_sets_overrun_if_rdrf_is_still_full(self):
+        sci = SCI1()
+
+        sci.inject_rx(0x11)
+        sci.inject_rx(0x22)
+
+        self.assertEqual(sci.read(SCI1_SSR) & (SCI_SSR_RDRF | SCI_SSR_ORER), SCI_SSR_RDRF | SCI_SSR_ORER)
+        self.assertEqual(sci.rdr, 0x11)
+
+    def test_uart_8n1_38400_byte_timing(self):
+        timing = UartTiming(baud=38_400)
+
+        self.assertEqual(timing.bits_per_character, 10)
+        self.assertAlmostEqual(timing.micros_per_character(), 260.416666, places=3)
+        self.assertEqual(timing.cycles_per_character(10_000_000), 2604)
+
 
 if __name__ == "__main__":
     unittest.main()