base.exe

compiler.rb

# -*- coding: utf-8 -*-

class String
  # offset 文字目から val の長さぶん val で置き換える
  def write(offset, val)
    self[offset, val.length] = val
  end
end

base = File.open("base.exe", "rb").read
text = [0xb8, 123, 0xc3].pack("CIC")
base.write(0x180, [text.length].pack("I"))
base.write(0x200, text)

File.open("output.exe", "wb").write(base)