Implements sub: passing tests

src/main/scala/projet/Alu.scala

@@ -5,7 +5,7 @@ import chisel3.util.switch
 import chisel3.util.is
 
 object AluOpCode extends ChiselEnum {
-    val Add, And, Or, Xor, ShiftLeft, ShiftRight, ShiftArithmeticRight,
+    val Add, Sub, And, Or, Xor, ShiftLeft, ShiftRight, ShiftArithmeticRight,
         LessThanSigned, LessThanUnsigned, GreaterEqualSigned,
         GreaterEqualUnsigned, Equal = Value
 }
@@ -28,6 +28,10 @@ class Alu extends Module {
             io.out := io.a + io.b;
         }
 
+        is(Sub) {
+            io.out := io.a - io.b;
+        }
+
         is(And) {
             io.out := io.a & io.b;
         }