mcdosbox-x/examples/ripterm_bezier.py

#!/usr/bin/env python3
"""Example: Tracing the Bezier algorithm in RIPTERM.EXE

This script demonstrates how to use the DOSBox-X MCP server to trace
the unpublished Bezier curve algorithm in RIPTERM.EXE.

The goal is to:
1. Launch DOSBox-X with RIPTERM
2. Set breakpoints at suspected Bezier drawing code
3. Feed a test RIPscrip file with Bezier commands
4. Capture register/memory state at each point
5. Reconstruct the algorithm from the captured data

Prerequisites:
- RIPTERM.EXE in the ./dos directory
- A test RIP file with Bezier commands
- DOSBox-X MCP server running

Usage:
    python examples/ripterm_bezier.py

Note: This is a conceptual example. The actual addresses would need to be
determined through static analysis (e.g., in Ghidra) first.
"""

import json
import time
from pathlib import Path


def trace_bezier():
    """Trace the Bezier algorithm execution."""

    # These would be determined from Ghidra analysis
    # Hypothetical addresses for RIPTERM's Bezier code
    BEZIER_ENTRY = "1234:0100"  # Where Bezier processing starts
    DRAW_POINT = "1234:0200"   # Where individual points are drawn
    CALCULATE = "1234:0300"    # The core calculation routine

    print("=" * 60)
    print("RIPTERM Bezier Algorithm Tracer")
    print("=" * 60)
    print()

    # This would use the MCP tools via Claude or direct API
    # For demonstration, we'll show the intended flow:

    print("Step 1: Launch DOSBox-X with RIPTERM")
    print("  launch('/path/to/dos/RIPTERM.EXE')")
    print()

    print("Step 2: Attach to GDB stub")
    print("  attach('localhost', 1234)")
    print()

    print("Step 3: Set breakpoints at key addresses")
    print(f"  breakpoint_set('{BEZIER_ENTRY}')  # Bezier entry")
    print(f"  breakpoint_set('{DRAW_POINT}')    # Draw point")
    print(f"  breakpoint_set('{CALCULATE}')     # Calculation")
    print()

    print("Step 4: Continue execution until breakpoint")
    print("  continue_execution()")
    print()

    print("Step 5: When breakpoint hit, capture state:")
    print("""
  # Read registers
  regs = registers()
  print(f"AX={regs['ax']} BX={regs['bx']} CX={regs['cx']} DX={regs['dx']}")

  # Read stack (parameters often passed on stack)
  stack_data = stack(16)

  # Read data segment (for global variables)
  mem = memory_read("DS:0000", 256)

  # Step through to see calculation
  for i in range(100):
      step()
      regs = registers()
      # Log coordinate values
      print(f"Step {i}: X={regs['cx']} Y={regs['dx']}")
""")

    print("Step 6: Analyze captured data to reconstruct algorithm")
    print()

    # Example of what the captured data might look like
    example_trace = [
        {"step": 0, "x": 100, "y": 50, "note": "Control point 1"},
        {"step": 10, "x": 112, "y": 58, "note": "Interpolated"},
        {"step": 20, "x": 125, "y": 65, "note": "Interpolated"},
        {"step": 30, "x": 138, "y": 71, "note": "Interpolated"},
        {"step": 40, "x": 150, "y": 75, "note": "Control point 2 region"},
        {"step": 50, "x": 162, "y": 71, "note": "Curving back"},
        {"step": 60, "x": 175, "y": 65, "note": "Interpolated"},
        {"step": 70, "x": 188, "y": 58, "note": "Interpolated"},
        {"step": 80, "x": 200, "y": 50, "note": "End point"},
    ]

    print("Example trace output:")
    print("-" * 40)
    for point in example_trace:
        print(f"  Step {point['step']:3d}: ({point['x']:3d}, {point['y']:3d}) - {point['note']}")
    print()

    print("From this data, we could determine:")
    print("  - Whether it uses De Casteljau's algorithm")
    print("  - The number of subdivisions")
    print("  - Fixed-point vs floating-point math")
    print("  - Any optimizations or approximations")


def create_test_rip():
    """Create a simple RIP file to test Bezier drawing."""

    # RIPscrip Level 0 Bezier command
    # The format is: !|z<x1><y1><x2><y2><x3><y3><x4><y4>
    # Using MegaNum encoding

    test_rip = """!|
!|E
!|c0F
!|z00320064009600C800C8006400640032
"""

    # This draws a Bezier curve with:
    # Start: (50, 100)
    # Control 1: (150, 200)
    # Control 2: (200, 100)
    # End: (100, 50)

    test_file = Path("dos/test-bezier.RIP")
    test_file.parent.mkdir(exist_ok=True)
    test_file.write_text(test_rip)

    print(f"Created test file: {test_file}")
    return test_file


def main():
    """Main entry point."""
    print()
    trace_bezier()
    print()
    print("=" * 60)
    print("To actually run this:")
    print("1. Use Ghidra to find the real Bezier addresses in RIPTERM.EXE")
    print("2. Start the DOSBox-X MCP server")
    print("3. Use Claude to interactively debug with these tools")
    print("=" * 60)


if __name__ == "__main__":
    main()