terranigma_rng.lua

-- Window properties
local title = "     RNG     "
local nr_rows = 16
local nr_columns = 2
local column_width = 6

local targetxpos = 0
local targetypos = 36
local xpos = targetxpos
local ypos = targetypos

local getCollapsedWidth = function()
  return (math.max(column_width,string.len(title))+1)*4
end

local my_text = function(x,y,counter,rn)
  gui.text(x,y,string.upper(string.format('%02x: %02x',counter,rn)))
end

local my_display = function()

  -- Update the position of the RNG window
  if ypos<targetypos then
    ypos = ypos + 1
  elseif ypos>targetypos then
    ypos = ypos - 1
  end
  if xpos<targetxpos then
    xpos = xpos + 1
  elseif xpos>targetxpos then
    xpos = xpos - 1
  end

  -- Read the current state of the RNG
  local currentRNG = memory.readbyterange(0x7e0408,16)

  -- Render the title box
  gui.box (xpos,ypos-9,xpos+4*(string.len(title)+1) ,ypos-1,0x000000FF)
  gui.text(xpos+3,ypos-8,title)

  -- Render the RNG boxes
  for c=0,math.floor(nr_columns)-1 do

    local xcolumn = xpos+c*(column_width+1)*4*(1-math.abs(xpos/getCollapsedWidth()))
    gui.box (xcolumn,  ypos,  xcolumn+(column_width+1)*4 ,ypos+nr_rows*8+2,0x00000080)

    for n=0,math.floor(nr_rows)-1 do

      -- Render the text
      my_text(xcolumn+3,ypos+(n)*8+2,currentRNG[16],currentRNG[1])

      -- Update the set of random numbers to predict the next one
      local carry = 0
      local temp
      for i=16,2,-1 do
        temp  = currentRNG[i-1]+currentRNG[i]+carry
        currentRNG[i-1] = AND(temp,0xff)
        carry = (temp-AND(temp,0xff))/256
      end

      i=16
      repeat
        currentRNG[i]=AND(currentRNG[i]+1,0xff)
        i=i-1
      until i<1 or currentRNG[i+1]~=0
    --
    end

  end
end

-- Hook the display function to the GUI update
local on_gui_update_old = gui.register()
local function on_gui_update_new()
  if on_gui_update_old then
    on_gui_update_old()
  end
  my_display()
end
gui.register(on_gui_update_new)

-- Create a public RNG object to interact with
rng      = {}
rng.show = function() targetxpos = 0 end
rng.hide = function() targetxpos = -(getCollapsedWidth()+1) end
rng.set_title = function( new_title ) title = new_title end
rng.set_text = function( new_text ) my_text = new_text end
rng.set_nr_rows = function( new_nr_rows ) nr_rows = new_nr_rows end
rng.set_nr_columns = function( new_nr_columns ) nr_columns = new_nr_columns end
rng.set_column_width = function( new_column_width ) column_width = new_column_width end