Finish debugger

The emulator has a handful of debugger views implemented so far, and most of them are interactive, but not very useful.

Below is a raw dump of everything I planned to do for the debugger:

SMPC

• Raw registers view
• Command log/trace, including all parameters and responses
• Pending INTBACK state
• Peripheral (controller) states (and maybe raw reports, but might be too memory-intensive)
• RTC state and settings

CD block

• Raw registers view
• Current status, maybe a status change trace?
• Interrupts
• Command log/trace, including all parameters and responses
• Transfer logs (including pointers to data in disc if possible)
• Filters view
• Buffer partitions view
• Filesystem view
  • Include the standard Saturn file format viewers here (stretch goal)

SH-2

• Disassembly view
  • Scrollable disassembly view
  • Single-step (step in, step over, step out)
  • Branch arrows
  • Call stack (fix bugs and figure out call/return patterns in the existing tracer)
  • Breakpoints
  • Watchpoints
  • Assemble code
  • Load and display symbols from .elf files, maybe other types
• On-chip peripherals
  • Power (SBYCR)
  • BSC
  • SCI
  • UBC
• Stack view (memory view focused on stack pointer with annotations like "return address", "stack frame", etc.)
• Highlight cache hits on cached memory region
• Instruction trace
• Memory access trace
• Exception trace
• Combined event view (breakpoints, watchpoints, interrupts, exceptions, anything traced by the CPU)
• Suspend CPU option (disable CPU during emulation; everything else still runs)

M68K

• Disassembly view
  • Registers view
  • Stack views: memory views focused on each stack pointer, annotated with the contents (e.g. return addresses, allocated frames, etc.)
  • Instruction trace
  • Memory access trace
  • Exception trace
  • Interrupts
  • Interrupt trace
  • Single-step (step in, step over, step out)
  • Branch arrows
  • Call stack (fix bugs and figure out call/return patterns in the existing tracer)
  • Breakpoints
  • Watchpoints
  • Assemble code
  • Load and display symbols from .elf files
• Open memory viewer
• Combined event view (breakpoints, watchpoints, interrupts, exceptions, anything traced by the CPU)
• Suspend CPU option (disable CPU during emulation; everything else still runs)

SCU

• DSP view
  • Controls (start, stop, pause, step)
  • Branch arrows
  • Execution trace
  • Breakpoints, watchpoints
  • Assemble code

VDPs

• Raw registers view
• Raw VRAM/CRAM/FBRAM views
  • Colored VDP2 CRAM view
  • VDP1 command list
  • Display both VDP1 framebuffers graphically
• Tile view
• Background (NBG/RBG) view with plane > page > charpat > cell > dot breakdown
  • Rotation parameter tables
  • Line scroll tables
• Line color and back screen views
• Sprite layer view
• Composite layer view with details on how each pixel is drawn
• Windows view
• Frame capture (single-shot, continuous, last N frames snapshot)
• Standard Saturn graphics format viewers - textures, 3D models, etc. (stretch goal)
• Implementation notes
  • Refactor VDP to allow capturing the entire state
    • Move VDP state into a dedicated object
    • Move renderer into a dedicated class
    • Make renderer consume a VDP state object to render graphics
      • Optionally consume a list of events (memory writes, VCNT increments) for captured states
        • Writes stored as XOR values to allow going forward or backward
      • Expose renderer on the public interface
      • Use the renderer on the frontend to draw the VDP state
      • Allow editing command list on the fly in frame capture window and see results in real time
  • Add note in mainpage.hpp documentation that some VDP tracers will execute from the renderer thread if that option is enabled

SCSP

• Raw registers view
• General registers
  • Master volume
  • DAC 18-bit toggle
  • 4 Mbit RAM toggle
• Slots/channels view
  • "Piano roll" view (shows played notes over time)
    • Color notes by slot or by sample start address
  • Oscilloscopes, spectrum analyzers, frequency graphs, etc.
• Sample collector/extractor
• Noise LFSR output
• LFOs
• CDDA output
• Interrupts (SCU, M68K)
• Timers
• Monitor/slot call view, displaying value for all slots
  • Highlight currently selected slot
• DMA transfer trace
• DSP view
  • All memory blocks
  • Program disassembly
  • Execution traces
  • Memory transfer traces
• FM algorithms graph view
• MIDI events trace/view
• DSP view
  • Branch arrows
  • Breakpoints, watchpoints
  • Assemble code
• Standard Saturn sound drivers/engines - TON, SEQ, etc. (stretch goal)