Vs. System DIP Switch Setter for Mesen2

VsDIPSwitch.lua

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-- Name: Vs. System DIP Switch Setter
-- Author: TakuikaNinja
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-- Simulates the Vs. System's DIP switch settings, for games not tracked in Mesen2's database.
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-- DIP switch setting (8 bits)
-- this is reversed from typical DIP switch ordering
-- rightmost bit is switch 1, leftmost bit is switch 8
-- examples: 00000111 = free play in Vs. SMB
dipSwitch = "00000000"

-- Do not touch anything below this
local consoleType = emu.getState()["consoleType"]
if consoleType ~= "Nes" then
	emu.displayMessage("Script", "This script only works on the NES/FC.")
	return
end

P1_DATA = 0x18 -- %00011000
P2_DATA = 0xFC -- %11111100

function poll(address, value)
	local output = value
	
	local bits = 0
	if address == 0x4016 then
		output = value & ~P1_DATA
		bits = (tonumber(dipSwitch,2) & 3) << 3
	elseif address == 0x4017 then
		output = value & ~P2_DATA
		bits = tonumber(dipSwitch,2) & P2_DATA
	end
	
	-- compose & return final output
	output = (output | bits) & 0xff
	return output
end

emu.displayMessage("Script", "Vs. System DIP switch setter")
emu.log(string.format("DIP switch = %#02x", tonumber(dipSwitch,2)))

emu.addMemoryCallback(poll, emu.callbackType.read, 0x4016)
emu.addMemoryCallback(poll, emu.callbackType.read, 0x4017)