L6502

L6502 is a 6502 library implemented in Lua.
Undefined instructions are not implemented. (Because the instructions differ from chip to chip)

Environment

Supports Lua 5.1 to 5.4 and LuaJIT 2.0.

Including

• CPU Emulator
• Assembler
• Disassembler
• Interpreter

How to Run

-- Load library
local L6502		= require("L6502")
local L6502Memory	= require("L6502Memory")

-- Create memory
memory	= L6502Memory.new()
memory:Upload(0xFFFA, {0x00, 0x80, 0x00, 0x90, 0x00, 0xA0})	-- Interrupt handler
memory:Upload(0x9000, {0xEA})	-- Program code (Reset: NOP)

-- Create cpu
cpu	= L6502.new(memory, print)	-- print is a function that displays the trace log

-- Execute cpu
cpu:Reset()	-- Go to Reset routine
cpu:Clock()	-- Execute instruction
		--   To execute the next instruction,
		--   need to call cpu:Clock() for the currently executing instruction cycle.
		--   cpu:Step() advances the clock to the next instruction in one call.

--[[ Output:
NOP             ; PC=9000, A=00, X=00, Y=00, S=FD, P=34 nvRBdIzc, Cycle=0
]]

See also Sample directory.

For NES

Set cpu.DisableDecimalMode to true to ignore the D flag.
L6502Memory_NES.lua provides .nes file reading and mapper. (currently only mapper 0, 4)

ToDo

• CPU : Memory accurate access (RMWW, dummy read)
• CPU : Cycle accurate (probably remake)
• Assembler : .include directive
• Assembler : .if directive
• Interpreter : breakpoint commands

License

MIT License.