Color summing
=============

First let's define a Color ``Bundle`` with an addition operator.

.. code-block:: scala

     case class Color(channelWidth: Int) extends Bundle {
       val r = UInt(channelWidth bits)
       val g = UInt(channelWidth bits)
       val b = UInt(channelWidth bits)

       def +(that: Color): Color = {
         val result = Color(channelWidth)
         result.r := this.r + that.r
         result.g := this.g + that.g
         result.b := this.b + that.b
         return result
       }

       def clear(): Color ={
         this.r := 0
         this.g := 0
         this.b := 0
         this
       }
     }

Then let's define a component with a ``sources`` input which is a vector of colors, and a ``result`` output which is the sum of the ``sources`` input.

.. code-block:: scala

     class ColorSumming(sourceCount: Int, channelWidth: Int) extends Component {
       val io = new Bundle {
         val sources = in Vec(Color(channelWidth), sourceCount)
         val result = out(Color(channelWidth))
       }

       var sum = Color(channelWidth)
       sum.clear()
       for (i <- 0 to sourceCount - 1) {
         sum \= sum + io.sources(i)
       }
       io.result := sum
     }