1 files changed, 98 insertions, 0 deletions
diff --git a/atk16_emu/debugger.py b/atk16_emu/debugger.py
new file mode 100644
index 0000000..f887ed0
--- /dev/null
+++ b/atk16_emu/debugger.py
@@ -0,0 +1,98 @@
+from getch import getche
+from .emu import Machine
+
+class Debugger:
+  def __init__(self):
+    self.rom_image = None
+    self.breakpoints: set[int] = set()
+    self.machine = Machine()
+    self.machine.reset()
+    self.machine.run()
+
+  def load_rom_image(self, rom_image: bytearray) -> None:
+    self.rom_image = rom_image
+    self.machine.load_rom_image(rom_image)
+
+    print("Loaded rom image.")
+
+  def print_pc_context(self):
+    print("=== Program context")
+    for i in range(-4, 5):
+      addr = self.machine.pc.value + i
+      if addr < 0 or addr >= 64 * 2 ** 16:
+        continue
+
+      if i == 0:
+        print(f"> 0x{addr:>04x}: 0x{self.machine.mem_read(addr):>04x}")
+      else:
+        print(f"  0x{addr:>04x}: 0x{self.machine.mem_read(addr):>04x}")
+
+    print()
+
+  def activate(self):
+    print("=== ATK16 debugger ===")
+    print("Press ? to show command help. Press q to quit.")
+    print()
+
+    while True:
+      self.print_pc_context()
+      print("dbg> ", end="", flush=True)
+      cmd = getche()
+      print()
+
+      if cmd == "q":
+        break
+      elif cmd == "?":
+        self.print_help()
+      elif cmd == "r":
+        while self.machine.running:
+          self.machine.step()
+          if self.machine.pc.value in self.breakpoints:
+            print(f"Breakpoint hit at 0x{self.machine.pc.value:>04x}")
+            break
+
+        if not self.machine.running:
+          print("Machine halted.")
+
+      elif cmd == "b":
+        print("Set breakpoints:")
+        for addr in self.breakpoints:
+          print(f"  0x{addr:>04x}")
+        if len(self.breakpoints) == 0:
+          print("<no breakpoints>")
+        print()
+
+        try:
+          addr = eval(input("Breakpoint address: "), {})
+        except:
+          print("Cancelled")
+          continue
+        if type(addr) != int or addr < 0 or addr >= 64 * 2 ** 16:
+          print("Invalid address")
+
+        if addr in self.breakpoints:
+          self.breakpoints.remove(addr)
+          print(f"Removed breakpoint at 0x{addr:>04x}")
+        else:
+          self.breakpoints.add(addr)
+      elif cmd == "n":
+        self.machine.step()
+      elif cmd == "s":
+        self.machine.print_state_summary()
+      elif cmd == "0":
+        self.machine.reset()
+        print("Machine reset.")
+      else:
+        print(f"Unknown command: {cmd}")
+
+  def print_help(self):
+    print("Debugger commands:")
+    print("  r     run until next breakpoint or until halted")
+    print("  n     step forward")
+    print("  b     step backward")
+    print("  b     set or remove breakpoint")
+    print("  s     show state summary")
+    print("  0     reset the machine state")
+    print("  q     quit")
+    print("  ?     show this help")
+    print()