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simak65 - 6502 CPU simulator library

This simulator is based on the simualator of AK6502 CPU. NMOS version of the CPU is simulated, cycle accurate. There's no undocumented intructions support, invalid opcodes are decoded as nop.

Build

There're no dependencies, only make and gcc are needed. Simply type make to build the library. It can be installed to /usr/local/lib via sudo make install, along with the api header (to /usr/local/include).

API

Library interface is available in simak65.h header.

struct simak65_bus

This structure holds CPU bus read/write callback, that are need to provided by the library user.

struct simak65_cpustate

This structure holds internal CPU state. It is stored by the library user and needs to be passed to the library functions.

void simak65_step(struct simak65_cpustate *cpu, unsigned int *cycles)

Execute the next instruction.

  • cpu - cpu state,
  • cycles - optional (can be NULL), number of cycles passed for the execution of the instruction is added to this variable.

void simak65_rst(struct simak65_cpustate *cpu, unsigned int *cycles)

Perform the CPU reset. This operation must be performed pefored before executing first instruction.

  • cpu - cpu state,
  • cycles - optional (can be NULL), number of cycles passed for the execution of the instruction is added to this variable.

void simak65_nmi(struct simak65_cpustate *cpu, unsigned int *cycles)

Execute the non-maskable interrupt.

  • cpu - cpu state,
  • cycles - optional (can be NULL), number of cycles passed for the execution of the instruction is added to this variable.

void simak65_irq(struct simak65_cpustate *cpu, unsigned int *cycles)

Execute the interrupt.

  • cpu - cpu state,
  • cycles - optional (can be NULL), number of cycles passed for the execution of the instruction is added to this variable.

void simak65_init(struct simak65_cpustate *cpu, const struct simak65_bus *ops)

Initialize the library and the cpu state.

  • cpu - cpu state,
  • ops - CPU memory bus callbacks.

License

See LICENSE for details.