[ruby] NUS 11/12 Sem 1 CS2100 Tutorial 11 Q2c

q2c.rb

class Cache
  def split(addr)
    x = addr >> 3
    return [x & 3, x >> 2]
  end

  attr_reader :misses, :hits

  def initialize
    @misses = 0
    @hits = 0
    @cache = Array.new(4, nil)
  end

  def update(addr)
    index, tag = split(addr)
    old_tag = @cache[index]
    r = !old_tag.nil? && old_tag == tag
    if r
      @hits += 1
    else
      @cache[index] = tag
      @misses +=1
    end
    return r
  end
end

def q2c
  a = 0x1000
  b = 0x4010
  c = Cache.new
  999.times do
    a += 4
    b += 4
    c.update(a)
    c.update(b)
    c.update(a-4)
  end
  puts "hits: #{c.hits}"
  puts "misses: #{c.misses}"
end