Life.scala

// See LICENSE.txt for license details.
package TutorialExamples

import Chisel._
import util.Random

class Cell(isBorn: Boolean) extends Module {
  val io = new Bundle {
    val nbrs = Vec(8, Bool(INPUT))
    val out  = Bool(OUTPUT)
  }
  val isAlive = Reg(init=Bool(isBorn))
  val count   = io.nbrs.foldRight(UInt(0, 3))((x: Bool, y: UInt) => x.toUInt + y)
  when (count < UInt(2)) {
    isAlive := Bool(false)
  } .elsewhen (count < UInt(4)) {
    isAlive := Bool(true)
  } .elsewhen (count >= UInt(4)) {
    isAlive := Bool(false)
  } .elsewhen(!isAlive && count === UInt(3)) {
    isAlive := Bool(true)
  }
  io.out := isAlive
}

class Life(val n: Int) extends Module {
  val tot = n*n
  val io = new Bundle {
    val state = Vec(tot, Bool(OUTPUT))
  }
  def idx(i: Int, j: Int) = ((j+n)%n)*n+((i+n)%n)
  val rnd = new Random(1)
  val cells = Range(0, tot).map(i => Module(new Cell(rnd.nextInt(2) == 1)))
  for (k <- 0 until tot)
    io.state(k) := cells(k).io.out
  for (j <- 0 until n) {
    for (i <- 0 until n) {
      val cell = cells(j*n + i)
      var ni = 0
      for (dj <- -1 to 1) {
        for (di <- -1 to 1) {
          if (di != 0 || dj != 0) {
            cell.io.nbrs(ni) := cells(idx(i+di, j+dj)).io.out
            ni = ni + 1
          }
        }
      }
    }
  }
}

class LifeTests(c: Life) extends Tester(c) {
  for (t <- 0 until 16) {
    step(1)
    for (j <- 0 until c.n) {
      for (i <- 0 until c.n) {
        print(peek(c.io.state(c.idx(i, j))))
      }
      println()
    }
  }
}