magic6502

Simple NMOS 6502 emulation library (without decimal mode)

Building

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

make

API

Initialization

magic6502_ctx* magic6502_init(void* app_ctx, unsigned char* (*ma)(void*, unsigned short));

Parameters:

• app_ctx: Pointer to an application context. Used in ma callback. Optional.
• ma: Callback for memory access. Parameters are the application context and memory address, respectively. Should return pointer to the requested memory.

Interrupts

void magic6502_interrupt(magic6502_ctx* ctx, char type);

Parameters:

• ctx: Pointer to the context returned from initialization.
• type: Type of interrupt to execute.
  • MAGIC6502_INT_BRK
  • MAGIC6502_INT_IRQ
  • MAGIC6502_INT_NMI
  • MAGIC6502_INT_RESET

Execution

The library is designed to execute one instruction per magic6502_exec call.

unsigned char magic6502_exec(magic6502_ctx* ctx);

Parameters:

• ctx: Pointer to the context returned from initialization.

Returns amount of CPU "cycles" consumed during instruction execution. This is useful for timing.

Memory access tracking

Basic memory access tracking is available via two variables in magic6502_ctx. address_accessed will provide the accessed memory address from the last instruction, if any (0 if there was no memory access). is_last_instr_write is a boolean which indicates whether the last instruction was a memory write.

Cleanup

void magic6502_free(magic6502_ctx* ctx);

Tests

Test execution

Run test in the bin folder after building. It will execute all instructions in functional_test.bin.

Functional test is from https://github.com/Klaus2m5/6502_65C02_functional_tests