magic2c02

Partially working Ricoh 2C02 PPU emulation library

Kind of working, kind of broken

Not supported:

• Sprite flipping
• Nametable mirroring (except for horizontal mirroring)
• PPU master/slave select
• Color emphasis/PPUMASK register
• PAL (NTSC only)

Building

Should build with gcc/make. I used MinGW (32-bit) and MSYS to build this on Windows.

make

API

Initialization

magic2c02_ctx* magic2c02_init(unsigned char* (*cpu_ma) (void*, unsigned short),
  void (*cpu_interrupt)(void*),
  void* cpu_ctx,
  void (*render)(void*, unsigned char*));

Parameters:

• cpu_ma: Callback for main memory access. Parameters are the application context and memory address, respectively. Should return pointer to the requested memory.
• cpu_interrupt: Callback for invoking on NMI on the CPU.
• cpu_ctx: Pointer to an application context. Used in cpu_ma, cpu_interrupt and render callbacks. Optional.
• render: Callback for displaying rendered image to screen. First argument is application context. Second argument is an RGB array.

PPU register processing

Should probably execute this before you render a scanline. Uses the NES CPU/PPU register mappings ($2000-2007 / $4014).

void magic2c02_process_registers(magic2c02_ctx* ctx, unsigned short last_memory_access_addr);

Parameters:

• ctx: Pointer to the context returned from initialization.
• last_memory_access_addr: Memory access address from last CPU instruction. 0 if no memory access in last instruction.

Execution

void magic2c02_render_scanline(magic2c02_ctx* ctx);

Parameters:

• ctx: Pointer to the context returned from initialization.

Cleanup

void magic2c02_free(magic2c02_ctx* ctx);

Tests

Test build/execution

"Test" program depends on SDL 2. The Makefile assumes you have an SDL build in the parent directory.

make test

Run test in the bin folder after building.