Data commit

Task/Four-bit-adder/Scala/four-bit-adder-1.scala

@@ -0,0 +1,26 @@
+object FourBitAdder {
+   type Nibble=(Boolean, Boolean, Boolean, Boolean)
+
+   def xor(a:Boolean, b:Boolean)=(!a)&&b || a&&(!b)
+
+   def halfAdder(a:Boolean, b:Boolean)={
+      val s=xor(a,b)
+      val c=a && b
+      (s, c)
+   }
+
+   def fullAdder(a:Boolean, b:Boolean, cIn:Boolean)={
+      val (s1, c1)=halfAdder(a, cIn)
+      val (s, c2)=halfAdder(s1, b)
+      val cOut=c1 || c2
+      (s, cOut)
+   }
+
+   def fourBitAdder(a:Nibble, b:Nibble)={
+      val (s0, c0)=fullAdder(a._4, b._4, false)
+      val (s1, c1)=fullAdder(a._3, b._3, c0)
+      val (s2, c2)=fullAdder(a._2, b._2, c1)
+      val (s3, cOut)=fullAdder(a._1, b._1, c2)
+      ((s3, s2, s1, s0), cOut)
+   }
+}

Task/Four-bit-adder/Scala/four-bit-adder-2.scala

@@ -0,0 +1,15 @@
+object FourBitAdderTest {
+   import FourBitAdder._
+   def main(args: Array[String]): Unit = {
+      println("%4s   %4s   %4s %2s".format("A","B","S","C"))
+      for(a <- 0 to 15; b <- 0 to 15){
+         val (s, cOut)=fourBitAdder(a,b)
+         println("%4s + %4s = %4s %2d".format(nibbleToString(a),nibbleToString(b),nibbleToString(s),cOut.toInt))
+      }
+   }
+
+   implicit def toInt(b:Boolean):Int=if (b) 1 else 0
+   implicit def intToBool(i:Int):Boolean=if (i==0) false else true
+   implicit def intToNibble(i:Int):Nibble=((i>>>3)&1, (i>>>2)&1, (i>>>1)&1, i&1)
+   def nibbleToString(n:Nibble):String="%d%d%d%d".format(n._1.toInt, n._2.toInt, n._3.toInt, n._4.toInt)
+}