Add a new debugger interface using a simple command language. This is
less powerful than the scheme interface (which still exists) but more
ergonomic for interactive debugging.
This debugger has no external dependencies (it will however use readline
if available) and is included in builds by default.
A sample interaction might look like:
xsystem4 --debug /path/to/game
dbg(cmd)> breakpoint bar
Set breakpoint at function 'bar' (0x00001234)
dbg(cmd)> continue
Hit breakpoint at function 'bar' (0x00001234)
dbg(cmd)> backtrace
#0 0x00001234 in bar
#1 0x00002222 in foo
#2 0x00004444 in main
dbg(cmd)> locals
[0] i: 2
[1] s: "baz"
dbg(cmd)> locals 1
[0] j: 3
[1] obj: { m_i = 0; m_s = "" }
dbg(cmd)> quit
This is implemented by inserting special opcodes into the game's code.
When the breakpoint handler is finished, it returns the original opcode
so that execute_instruction can continue executing normally.
E.g.
* start xsystem4 with --debug option to drop into debugger immediately
* run (bp "game_main")
* ^d or \exit to close debugger REPL
* ...drop into a debugger REPL again at the game_main function
- Create separate directories for source and header files.
- Build code shared between xsystem4 and aindump as a static library.
- Create header dirs gfx/ system4/ and vm/
- Make CG.c/h usable without a running VM
Nunuhara Cabbage