further digging and basic emulator

tests/test_emulator.py

@@ -0,0 +1,76 @@
+import unittest
+from pathlib import Path
+
+from h8536.emulator import (
+    HEARTBEAT_FRAME,
+    ON_CHIP_RAM_START,
+    REGISTER_FIELD_START,
+    SCI1_SCR,
+    SCI1_SSR,
+    SCI1_TDR,
+    SCI_SCR_TE,
+    SCI_SSR_TDRE,
+    H8536Emulator,
+    MemoryMap,
+    SCI1,
+    discover_rom_path,
+    load_rom,
+)
+
+
+class EmulatorHarnessTest(unittest.TestCase):
+    def test_memory_map_routes_rom_ram_register_and_external(self):
+        memory = MemoryMap(bytes([0x12, 0x34, 0x56, 0x78]))
+
+        self.assertEqual(memory.read8(0x0001), 0x34)
+        memory.write8(ON_CHIP_RAM_START, 0xA5)
+        self.assertEqual(memory.read8(ON_CHIP_RAM_START), 0xA5)
+        memory.write8(REGISTER_FIELD_START, 0x5A)
+        self.assertEqual(memory.read8(REGISTER_FIELD_START), 0x5A)
+        memory.write8(0xF000, 0x11)
+        self.assertEqual(memory.read8(0xF000), 0x11)
+
+    def test_sci_transmit_capture_requires_enabled_transmitter(self):
+        sci = SCI1()
+        sci.write(SCI1_TDR, 0x33)
+        self.assertEqual(sci.tx_bytes, [])
+        self.assertFalse(sci.tx_events[-1].emitted)
+
+        sci.write(SCI1_SCR, sci.scr | SCI_SCR_TE)
+        for byte in HEARTBEAT_FRAME:
+            sci.write(SCI1_TDR, byte)
+
+        self.assertEqual(bytes(sci.tx_bytes), HEARTBEAT_FRAME)
+        self.assertEqual(sci.tx_frames, [HEARTBEAT_FRAME])
+        self.assertTrue(sci.saw_heartbeat())
+        self.assertTrue(sci.read(SCI1_SSR) & SCI_SSR_TDRE)
+
+    def test_vector_decoding_uses_minimum_mode_reset_word(self):
+        rom = bytearray(0x1004)
+        rom[0:2] = b"\x10\x00"
+        rom[0x1000] = 0x00
+
+        emulator = H8536Emulator(bytes(rom))
+
+        self.assertEqual(emulator.reset_vector(), 0x1000)
+        self.assertEqual(emulator.cpu.pc, 0x1000)
+        self.assertEqual(emulator.vectors[0x0000][1], 0x1000)
+
+    def test_harness_instantiates_on_repo_artifacts(self):
+        root = Path(__file__).resolve().parents[1]
+        rom_path = discover_rom_path(root)
+        self.assertIsNotNone(rom_path)
+        rom_bytes, loaded_path = load_rom(root=root)
+
+        emulator = H8536Emulator(rom_bytes)
+        report = emulator.run(max_steps=4)
+
+        self.assertEqual(loaded_path, rom_path)
+        self.assertEqual(emulator.reset_vector(), 0x1000)
+        self.assertGreaterEqual(len(rom_bytes), 0x1002)
+        self.assertEqual(report.steps, 4)
+        self.assertFalse(report.heartbeat_seen)
+
+
+if __name__ == "__main__":
+    unittest.main()