Bill & Ted NES Mesen lua script

Bill & Ted.lua

-- bill & ted NES Mesen lua script
-- coded by karmic, jan 18-20, 2022

figure_names = {"Cleopatra","Confucius","King Arthur","Christopher Columbus","Paul Revere","Jesse James","Al Capone","Elvis","Julius Caesar","Robin Hood","Rembrandt","William Shakespeare","George Washington","Sitting Bull","Thomas Edison","Marilyn Monroe","A stranger"}
bait_names = {"Major credit card","Fortune cookie","Holy grail","Compass","Megaphone","Uzi","Book of lawyer stuff","Headstone","Salad dressing","Bag-o-money","Paint roller","Stage prop","Pair of choppers","Lawn chair","Compact disc","Rose","Some stuff"}
good_stuff_names = {"Pudding","Firecracker","Textbook","Cassette tape","Coin","Key"}

-- helper functions
function concat11(lo, hi)
  return lo | (hi << 8)
end

function readcpu(addr)
  return emu.read(addr, emu.memType.cpuDebug, false)
end

function getprg(bank,addr)
  if addr < 0xc000 then bank = 0 end
  return (bank*0x4000)+(addr&0x3fff)
end

function readprg(bank, addr)
  return emu.read(getprg(bank,addr), emu.memType.prgRom, false)
end

function readprglittle(bank,addr)
  return emu.readWord(getprg(bank,addr), emu.memType.prgRom, false)
end

function readprgbig(bank, addr)
  return concat11(readprg(bank,addr+1), readprg(bank,addr))
end


-- ingame functions
function convert_coord(primary,secondary,cam,persp)
  -- get point at secondary=0
  local offs = primary-cam
  local x = offs*2 + 128
  local y
  if persp & 0x80 == 0x80 then
    -- horizontal --
    y = offs + 160
  else
    -- vertical --
    y = 160 - offs
  end
  
  -- adjust point for secondary
  if persp & 0x80 == 0x80 then
    x = x - (secondary*2)
  else
    x = x + (secondary*2)
  end
  y = y + secondary
  
  return x,y
end



-- main function
framecount = 0

function main()
  emu.clearScreen();
  
  -- only run if nmi vector is to main game
  if emu.readWord(0x09, emu.memType.cpuDebug, false) ~= 0xa9cd then return end
  
  -- get game state information
  local level = readcpu(0x1c)
  local world = readcpu(0x26)
  
  local bait_index = readcpu(0x03c8)
  local last_char = readcpu(0x0195)
  local last_item = readcpu(0x0196)
  local teleport_block = readcpu(0x0198)
  local bait_flags = emu.readWord(0x03c5,emu.memType.cpuDebug,false)
  
  local correct_figure = readcpu(0x03c7)
  local correct_figure_index = readcpu(0x03c9)
  
  local cam_coord_full = emu.readWord(0xd6,emu.memType.cpuDebug, false)
  local cam_coord = cam_coord_full & 0xfff
  local cam_sector = cam_coord_full >> 12
  
  local world_base = readprglittle(2, 0xcf56 + world*2)
  local sector_screens = readcpu(0xda)
  local sector_persp = sector_screens & 0x80
  sector_screens = sector_screens & 0x7f
  
  local sector_cmds = readcpu(0x06e8)
  local sector_cmd_base = emu.readWord(0x06e9,emu.memType.cpuDebug,false)
  
  
  
  -- draw sector commands
  do
    local cmdptr = sector_cmd_base
    local cmds = sector_cmds
    while cmds > 0 do
      local cmdid = readprg(2,cmdptr)
      if cmdid > 0x0f then break end
      
      local cmd_coord_full = readprgbig(2,cmdptr+1)
      local cmd_sector = cmd_coord_full >> 12
      local cmd_coord = cmd_coord_full & 0xfff
      
      
      -- get more detailed command info
      local sec_coord = 0
      local direction = nil
      local diameter = nil
      
      -- secondary coordinate?
      if cmdid == 5 or cmdid == 6 or cmdid == 7 or cmdid >= 9 then
        sec_coord = emu.read(getprg(2,cmdptr+3),emu.memType.prgRom,true)
      end
      -- direction?
      if cmdid == 3 then
        direction = readprg(2,cmdptr+3)
      elseif cmdid >= 9 then
        direction = readprg(2,cmdptr+4)
      end
      -- diameter?
      if cmdid == 6 or cmdid == 7 then
        diameter = readprg(2,cmdptr+4)
      end
      
      
      if diameter then
        -- draw a box with diameter
        local x1,y1 = convert_coord(cmd_coord-diameter,sec_coord-diameter,cam_coord,sector_persp)
        local x2,y2 = convert_coord(cmd_coord+diameter,sec_coord-diameter,cam_coord,sector_persp)
        local x3,y3 = convert_coord(cmd_coord+diameter,sec_coord+diameter,cam_coord,sector_persp)
        local x4,y4 = convert_coord(cmd_coord-diameter,sec_coord+diameter,cam_coord,sector_persp)
        
        emu.drawLine(x1,y1, x2,y2, 0xff00ff)
        emu.drawLine(x2,y2, x3,y3, 0xff00ff)
        emu.drawLine(x3,y3, x4,y4, 0xff00ff)
        emu.drawLine(x4,y4, x1,y1, 0xff00ff)
        
        -- draw string describing the item
        local strx = math.min(x1,x2,x3,x4)+2
        local stry = math.min(y1,y2,y3,y4)-12
        local item = readprg(2,cmdptr+5)
        
        local str
        local strbg = 0x7f000000
        local strcol = 0xffffff
        if cmdid == 6 then
          local bait = readcpu(0x019a+item+bait_index)
          if bait > 0x0f then
            str = "Already got"
          else
            str = bait_names[bait+1]
          end
          if bait == correct_figure and framecount % 20 >= 10 then
            strbg = 0x7fbfbf00
          end
        elseif cmdid == 7 then
          local unav = item == last_item
          item = item & 0x7f
          if item > 0x06 then
            str = "Invalid"
          else
            str = good_stuff_names[item+1]
          end
          if unav then
            strx = strx - 20
            str = str.." (unavailable)"
          end
        end
        
        emu.drawString(strx,stry,str,strcol,strbg)
      elseif direction then
        -- draw an arrow
        local x,y = convert_coord(cmd_coord,sec_coord,cam_coord,sector_persp)
        local xend,yend
        local xa1,ya1,xa2,ya2
        if sector_persp == 0x80 then direction = (direction+2)&7 end
        if direction == 0 then
          -- north
          xend = x + 20
          yend = y - 10
          xa1 = xend - 8
          ya1 = yend + 2
          xa2 = xend - 4
          ya2 = yend + 5
        elseif direction == 2 then
          -- east
          xend = x + 20
          yend = y + 10
          xa1 = xend - 8
          ya1 = yend - 2
          xa2 = xend - 4
          ya2 = yend - 5
        elseif direction == 4 then
          -- south
          xend = x - 20
          yend = y + 10
          xa1 = xend + 8
          ya1 = yend - 2
          xa2 = xend + 4
          ya2 = yend - 5
        elseif direction == 6 then
          -- west
          xend = x - 20
          yend = y - 10
          xa1 = xend + 8
          ya1 = yend + 2
          xa2 = xend + 4
          ya2 = yend + 5
        end
        emu.drawLine(x,y,xend,yend,0xff00ff)
        emu.drawLine(xend,yend,xa1,ya1,0xff00ff)
        emu.drawLine(xend,yend,xa2,ya2,0xff00ff)
        
        -- output string
        local strx = math.min(x,xend) - 10
        local stry = math.min(y,yend) - 12
        
        local str
        local strbg = 0x7f000000
        local strcol = 0xffffff
        
        if cmdid == 0x0b then
          str = "Blocked"
        elseif cmdid == 0x0c then
          str = "Exit"
        elseif cmdid == 0x0d then
          str = "Jail exit"
        elseif cmdid == 0x0e then
          if teleport_block == 0x0a then
            str = "Teleporter"
          else
            strx = strx - 10
            str = string.format("Blocked teleporter (%02X)",teleport_block)
          end
        elseif cmdid == 0x0f then
          str = "Unknown door $f"
        elseif cmdid == 0x09 then
          local charid = readprg(2,cmdptr+0x0e)
          if last_char == charid then
            strx = strx - 20
            str = "Unavailable character"
          else
            str = "Character"
          end
        elseif cmdid == 0x0a then
          local figix = readprg(2,cmdptr+0x0d)
          if figix == correct_figure_index and framecount % 20 >= 10 then
            strbg = 0x7f00ffff
          end
          strx = strx - 10
          if figix == correct_figure_index then
            strx = strx - 10
            if bait_flags & (1<<correct_figure) == 0 and framecount % 150 >= 75 then
              strx = strx - 20
              str = "...but you need a " .. bait_names[correct_figure+1] .. "."
            else
              str = figure_names[correct_figure+1] .. " is here!"
            end
          else
            str = "Historical figure"
          end
        end
        
        emu.drawString(strx,stry,str,strcol,strbg)
      elseif cmdid ~= 8 then
        -- otherwise just draw a line through the thing (ignore crossroads)
        local x,y = convert_coord(cmd_coord,sec_coord,cam_coord,sector_persp)
        if sector_persp == 0x80 then
          emu.drawLine(x-512,y+256,x+512,y-256,0xff00ff)
        else
          emu.drawLine(x-512,y-256,x+512,y+256,0xff00ff)
        end
        emu.drawString(x,y-12,cmdid,0xffffff,0x000000)
      end
      
      
      
      
      
      -- next command
      cmdptr = cmdptr + readcpu(0xafc1 + cmdid)
      cmds = cmds-1
    end
  end
  
  
  
  -- camera info
  emu.drawString(4,212,string.format("Camera: %i:%03X",cam_sector,cam_coord),0xffffff,0x9f0000ff)
  
  
  
  framecount = framecount + 1
end


-- init

emu.addEventCallback(main, emu.eventType.startFrame)