regenerator2000: Skill for Claude Code

Analyze Symbol Workflow

Use this skill when the user asks to "analyze this label", "what is this variable?", or "trace this address". This skill focuses on data flow—understanding what a memory location represents rather than just what code executes.

1. Determine Context & System

• Get the Target: If the user provides a label or address, use that. If not, use r2000_get_disassembly_cursor or r2000_get_address_details to identify the address under the cursor.
• Get the System: Use r2000_get_binary_info.
  • CRITICAL: Knowing the system is essential for identifying hardware registers and OS/KERNAL addresses. You MUST use your knowledge of the specific target computer's memory map, hardware registers, and OS entry points.
  • CONTEXT: Use the filename response and description (if provided) to identify the specific game or program. This allows you to infer domain-specific labels (e.g., "lap_counter" for a racing game, "lives" for a platformer) and look up known memory maps for popular titles.
  • UNDOCUMENTED OPCODES: If may_contain_undocumented_opcodes is true, the binary may use illegal/undocumented MOS 6502 opcodes. When tracing cross-references, be aware that instructions like LAX, SAX, DCP, etc. are valid and their read/write side effects must be considered in the data flow analysis.

2. Gather Usage Data

• Use r2000_get_cross_references on the target address.
  • This returns a list of everywhere the address is used (read, write, or modify).
  • Note: Pay attention to the instruction type at each reference.
    • Writes: STA, STX, STY, INC, DEC, ASL, LSR, ROR, ROL.
    • Reads: LDA, LDX, LDY, BIT, CMP, CPX, CPY, ADC, SBC.
    • Modify: INC, DEC, ASL, LSR, ROR, ROL (read-modify-write).
• If r2000_get_cross_references returns zero results:
  • The symbol may be referenced indirectly via a pointer — check if the address is in Zero Page ($00–$FF) and whether nearby code uses ($addr),Y or ($addr,X) patterns.
  • The symbol may be a well-known OS/KERNAL address that the disassembler doesn't generate an explicit cross-reference for — use your knowledge of the target system's memory map based on the system value from r2000_get_binary_info.
  • It may be dead code / an unused variable. Note this in the report.