Question

在使用Chisel3构建硬件组件方面，我是一个新手。现在，我正在尝试制作一个小模块，其中有2个输入（向量A和向量B）和1个输出（输出为1位无符号整数）。 Out是A和B的点积。

我声明了模块DotProduct进行计算。这是我的代码：

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这是我的简单测试

class RealDotProduct extends Module {
  val io = IO(new Bundle {
    val vectorA = Input(Vec(2, UInt(2.W)))
    val vectorB = Input(Vec(2, UInt(2.W)))
    val out  = Output(UInt(1.W))
  })

  val product = 0.U

  //Loop to calculate the inner (dot) product
  for (i <- 0 until 2) {
      product := product + io.vectorA(i) * io.vectorB(i)
  }
  io.out := product
}

我使用sbt运行测试，并得到了错误日志：

class RealDotProductTests(c: RealDotProduct) extends PeekPokeTester(c) {
  import scala.collection.immutable._  
  val in_a = Vector(0,1)
  val in_b = Vector(2,3)

  for (i <- 0 until 2) {
      poke (c.io.vectorA(i), in_a(i))
      poke (c.io.vectorB(i), in_b(i))
  }
  step(1)
  expect(c.io.out, 3)
}

class RealDotProductTester extends ChiselFlatSpec {
  behavior of "RealDotProduct"
  backends foreach {backend =>
    it should s"perform correct math operation on dynamic operand in $backend" in {
      Driver(() => new RealDotProduct, backend)((c) => new RealDotProductTests(c)) should be (true)
    }
  }
}
object RealDotProductMain extends App {
  iotesters.Driver.execute(args, () => new RealDotProduct) {
    c => new RealDotProductTests(c)
  }
}

问题1：能否请您告诉我我的问题出在哪里编码？
问题2：如果我想用vectorA和的随机值运行许多测试，我应该替换 expect（c.io.out，3）中的 3 向量B？

非常感谢你们。

Answer 1

答案1： Chisel正在组装代表所需硬件的连接图。您遇到的问题之一是将事物多次连接到导线product。在软件中这可能有意义，但在硬件中却没有那么重要。

如果您要口头描述您想做的事情，那可能就像是，“将inA和inB中的每个元素配对，并将它们相乘，然后将这些乘积之和加起来。在Chisel中，一种方法就是这样。

val products = io.vectorA.zip(io.vectorB).map { case (a, b) => a * b }
val sum = product.reduce { case (a, b) => a + b }
io,out := sum

该拉链将两个输入vec的元素配对。该映射将每对值转换为一系列乘积。然后，您可以使用reduce总结这些产品。

您的IO端口的宽度也有一些问题。您的out端口没有足够的位来包含两个向量的内积。 Chisel可以处理有关计算所需多少位的工作，但是对于IO端口，您仍然需要仔细考虑所需的位数。

很快，随着您对使用集合的scala习惯（例如Vec，Seq）越来越熟悉，您将能够编写更多此类模块简洁地说，是这样的：

  io.out := io.vectorA.zip(io.vectorB).map(_ * _).reduce(_ + _)

答案2：只需在测试仪中编写一个函数来计算值即可。解决该问题的基本方法是

var sum = 0 for（i <-in_a.indices）{ 总和+ =（in_a（i）* in_b（i）） }

... Expect（c.io.out，sum）

您可以做一些更奇特的事情。关于位的宽度。它应该足够大，可以处理您希望对任意输入进行计算得出的最大值。

使用Chisel3在两个信号4位之间的内积（点积。）

1 个答案: