Bizhawk shim for VBA-rr lua scripts

bizhawk-shim.lua

-- VBA/Bizhawk shim, to allow lua scripts written for VBA-rr to run in BizHawk.
-- Copy and paste this script into the start of a VBA-rr script to make it run in
-- BizHawk with no further modifications.

-- Changes to BizHawk's built-in tables persist while the lua console window is open.
-- Make sure we don't copy our already-updated objects.
if type(joypad.get) == "userdata" then
  bizJoypad = copytable(joypad)
end

if vba == nil then
  -- Assume we're in BizHawk and haven't yet applied the shim if vba is nil
  suppressPolyfillWarnings = false
  function warn(message)
    if not suppressPolyfillWarnings then
    console.log("WARNING: " .. message)
    end
  end

  --------------------------------------------------------------------------------------------
  -- Non-table functions                                                                    --
  --------------------------------------------------------------------------------------------
  
  addressof = function ()
    -- addressof intentionally not implemented because why on earth would you want to expose
    -- memory addresses of tables in the process to the lua script?
    error("addressof not implemented")
  end
  
  copytable = function (tbl)
    local result = {}
    for k,v in pairs(tbl) do
      result[k] = v
    end
    return result
  end
  
  AND = function(x1, ...)
    local result = x1
    for _,v in ipairs(arg) do
      result = bit.band(result,v)
    end
    return result
  end
  
  OR = function(x1, ...)
    local result = x1
    for _,v in ipairs(arg) do
      result = bit.bor(result,v)
    end
    return result
  end
  
  XOR = function(x1, ...)
    local result = x1
    for _,v in ipairs(arg) do
      result = bit.bxor(result,v)
    end
    return result
  end
  
  SHIFT = function(x, n)
    if n > 0 then
      return bit.rshift(x, n)
    else
      return bit.lshift(x, -n)
    end
  end
  
  BIT = function(...)
    local result = 0
    for _,v in ipairs(arg) do
      result = bit.set(result, v)
    end
    return result
  end
  
  --------------------------------------------------------------------------------------------
  -- vba/emu table                                                                          --
  --------------------------------------------------------------------------------------------
  vba = {
    frameadvance = emu.frameadvance,
    pause = client.pause,
    framecount = emu.framecount,
    lagcount = emu.lagcount,
    lagged = emu.islagged,
    emulating = function ()
      warn("vba.emulating not implemented.  Assuming true.")
      return true
    end,
    registerbefore = event.oninputpoll,
    registerafter = event.onframeend,
    registerexit = event.onexit,
    message = gui.addmessage,
    print = console.log
  }
  
  --------------------------------------------------------------------------------------------
  -- memory table                                                                           --
  --------------------------------------------------------------------------------------------  
  
  memory.readbyte = function(address, domain)
    local domain = domain or "System Bus"
    return memory.read_u8(address, domain)
  end
  
  memory.readbyteunsigned = memory.readbyte
  
  memory.readword = function(address, domain)
    local domain = domain or "System Bus"
    return memory.read_u16_le(address, domain)
  end
  
  memory.readshort = memory.readword
  memory.readwordunsigned = memory.readword
  memory.readshortunsigned = memory.readword
  
  memory.readdword = function(address, domain)
    local domain = domain or "System Bus"
    return memory.read_u32_le(address, domain)
  end
  
  memory.readlong = memory.readdword
  memory.readdwordunsigned = memory.readdword
  memory.readlongunsigned = memory.readdword
  
  memory.readbytesigned = function(address, domain
    local domain = domain or "System Bus"
    return memory.read_s8(address, domain)
  end
  
  memory.readwordsigned = function(address, domain)
    local domain = domain or "System Bus"
    return memory.read_s16_le(address, domain)
  end
  
  memory.readshortsigned = memory.readwordsigned
  
  memory.readdwordsigned = function(address, domain)
    local domain = domain or "System Bus"
    return memory.read_s32_le(address, domain)
  end
  
  memory.readlongsigned = memory.readdwordsigned
  
  memory.writebyte = function(address, value, domain)
    local domain = domain or "System Bus"
    return memory.write_s8(address, value, domain)
  end
  
  memory.writeword = function(address, value, domain)
    local domain = domain or "System Bus"
    return memory.write_s16_le(address, value, domain)
  end
  
  memory.writeshort = memory.writeword
  
  memory.writedword = function(address, value, domain)
    local domain = domain or "System Bus"
    return memory.write_s32_le(address, value, domain)
  end
  
  memory.writelong = memory.writedword
  
  memory.registerwrite = function(addr, func)
    event.onmemorywrite(func, addr)
  end
  
  memory.register = memory.registerwrite
  
  memory.registerexec = function(addr, func)
    event.onmemoryexecute(func, addr)
  end
  
  memory.registerrun = memory.registerexec
  memory.registerexecute = memory.registerexec
  
  --------------------------------------------------------------------------------------------
  -- joypad table                                                                           --
  --------------------------------------------------------------------------------------------  
  
  -- Difference between BizHawk's joypad functions and VBA-rr's:
  -- * Button names are all title case in BizHawk
  -- * BizHawk also includes peripherals like the tilt sensor
  
  joypad = {
    get = function(controller)
      local buttons = bizJoypad.get()
      
      -- Translate title case button names to lowercase
      -- Removing the title case ones is probably unnecessary?
      buttons["start"] = buttons["Start"]
      buttons["select"] = buttons["Select"]
      buttons["left"] = buttons["Left"]
      buttons["right"] = buttons["Right"]
      buttons["up"] = buttons["Up"]
      buttons["down"] = buttons["Down"]
      
      return buttons
    end,
    
    read = joypad.get,
    
    getdown = function(controller)
      local buttons = joypad.get(controller)
      for k,v in pairs(buttons) do
        if not v then
          buttons[k] = nil
        end
      end
      
      return allButtons
    end,
    
    readdown = joypad.getdown,
    
    getup = function(controller)
      local buttons = joypad.get(controller)
      for k,v in pairs(buttons) do
        if v then
          buttons[k] = nil
        end
      end
      
      return buttons
    end,
    
    readup = joypad.getup,
    
    set = function(controller, buttons)
      local buttons = buttons or {}
      
      -- VBA-rr's joypad.set can only press new buttons, and not change
      -- a button to unpress.  Remove all "false" values to preserve
      -- functionality
      for k,v in pairs(buttons) do
        if not v then
          buttons[k] = nil
        end
      end
      
      bizJoypad.set(buttons)
    end,
    
    write = joypad.set
  }
end