CooPatch.lua

-- MMBN coop lua script test
-- requires Bizhawk w/ VBA-Next core
-- hooks ingame functions to create and complete events
-- events would be sent between players to simulate a Co-op experience 
-- currently only works with NTSC 3 Blue
-- by NMarkro
memory.usememorydomain("System Bus")

pressed = false
queue = {}
valid_registers = emu.getregisters()

end_main_func_addr = 0x08000322
-- function calls are addr+1 to call in THUMB mode
give_chip_func_addr = 0x08011281
give_zenny_func_addr = 0x0801480B
give_bugfrag_func_addr = 0x0801485F

-- IDEA: watch the function that sets chip library flags
-- send give_chip events with "amount = 0" to update the other player's library without adding the chip
-- this is mainly for when players pick up extra folders and folder 2
-- we can't actually call this by itself as it sets off anti-cheat
give_library_func_addr = 0x080112AE

--[[
hooks the end of the main function
code normally looks like this:
    0800031C    ldr     r0,=3006825h                        load some function addr into r0
    0800031E    mov     r14,r15                             move the PC into r14 for returning here
    08000320    bx r0                   <- hooking here     call the function loaded in r0
    08000322    b       80002B4h                            goes back to start of main loop
the idea is to call whatever function we want with r0 then rerun this code normally
--]]
function main_hook()
    if next(queue) ~= nil then
        local index, event = next(queue)
        emu.setregister("R0", event.addr)
        emu.setregister("R14", 0x0800031C)
    end
end

-- r0 is used to call functions and as function args
-- we need to set the args manually at the beginning of functions
function set_args(registers)
    for reg, value in pairs(registers) do
        if valid_registers[reg] ~= nil then
            emu.setregister(reg, value)
        end
    end
end

-- hooks the give_chip function
-- has 2 purposes, to create new events for other players or complete current queued events
function give_chip_hook()
    -- check if we called this function
    if emu.getregister("R14") == 0x0800031C then
        local index, event = next(queue)
        set_args(event.registers)
        table.remove(queue, 1)
    else
        -- the player was given this chip normally
        -- here you would create an event from the given args to be sent over the network
    end
end

-- hooks the give_zenny function
-- has 2 purposes, to create new events for other players or complete current queued events
function give_zenny_hook()
    -- check if we called this function
    if emu.getregister("R14") == 0x0800031C then
        local index, event = next(queue)
        set_args(event.registers)
        table.remove(queue, 1)
    else
        -- the player was given this zenny normally
        -- here you would create an event from the given args to be sent over the network
    end
end

-- hooks the give_bugfrag function
-- has 2 purposes, to create new events for other players or complete current queued events
function give_bugfrag_hook()
    -- check if we called this function
    if emu.getregister("R14") == 0x0800031C then
        local index, event = next(queue)
        set_args(event.registers)
        table.remove(queue, 1)
    else
        -- the player was given this bugfrag normally
        -- here you would create an event from the given args to be sent over the network
    end
end


event.onmemoryexecute(main_hook, end_main_func_addr)
-- bizhawk needs even addr for events
event.onmemoryexecute(give_chip_hook, give_chip_func_addr+1)
event.onmemoryexecute(give_zenny_hook, give_zenny_func_addr+1)
event.onmemoryexecute(give_bugfrag_hook, give_bugfrag_func_addr+1)

while true do
    local inputs = joypad.get()
    -- pressing L+R+A will give you 1x LavaStg T
    if inputs.L and inputs.R and inputs.A then
        if not pressed then
            -- for give_chip the args are
            -- R0 = chip_id
            -- R1 = chip_code
            -- R2 = amount
            local new_event = {
                addr=give_chip_func_addr, 
                registers={["R0"]=0x0B3,["R1"]=0x13,["R2"]=0x1}
            }
            table.insert(queue, new_event)
            pressed = true
        end
    -- pressing L+R+B will give you 1000z
    elseif inputs.L and inputs.R and inputs.B then
        if not pressed then
            -- for give_zenny the args are
            -- R0 = amount
            local new_event = {
                addr=give_zenny_func_addr, 
                registers={["R0"]=1000}
            }
            table.insert(queue, new_event)
            pressed = true
        end
    -- pressing L+R+Select will give you 10 bugfrags
    elseif inputs.L and inputs.R and inputs.Select then
        if not pressed then
            -- for give_bugfrag the args are
            -- R0 = amount
            local new_event = {
                addr=give_bugfrag_func_addr, 
                registers={["R0"]=10}
            }
            table.insert(queue, new_event)
            pressed = true
        end
    -- pressing L+R+Start will add AntiDmg to your library
    elseif inputs.L and inputs.R and inputs.Start then
        if not pressed then
            -- for give_chip the args are
            -- R0 = chip_id
            -- R1 = chip_code (shouldn't matter)
            -- R2 = amount (set to 0 to only update library)
            local new_event = {
                addr=give_chip_func_addr, 
                registers={["R0"]=0x0BF,["R1"]=0x01,["R2"]=0x0}
            }
            table.insert(queue, new_event)
            pressed = true
        end
    else
        pressed = false
    end

    emu.frameadvance()
end