March 2014 update

Task/Four-bit-adder/AutoHotkey/four-bit-adder.ahk

@@ -0,0 +1,42 @@
+A := 13
+B := 9
+N := FourBitAdd(A, B)
+MsgBox, % A " + " B ":`n"
+	. GetBin4(A) " + " GetBin4(B) " = " N.S " (Carry = " N.C ")"
+return
+
+Xor(A, B) {
+	return (~A & B) | (A & ~B)
+}
+
+HalfAdd(A, B) {
+	return {"S": Xor(A, B), "C": A & B}
+}
+
+FullAdd(A, B, C=0) {
+	X := HalfAdd(A, C)
+	Y := HalfAdd(B, X.S)
+	return {"S": Y.S, "C": X.C | Y.C}
+}
+
+FourBitAdd(A, B, C=0) {
+	A := GetFourBits(A)
+	B := GetFourBits(B)
+	X := FullAdd(A[4], B[4], C)
+	Y := FullAdd(A[3], B[3], X.C)
+	W := FullAdd(A[2], B[2], Y.C)
+	Z := FullAdd(A[1], B[1], W.C)
+	return {"S": Z.S W.S Y.S X.S, "C": Z.C}
+}
+
+GetFourBits(N) {
+	if (N < 0 || N > 15)
+		return -1
+	return StrSplit(GetBin4(N))
+}
+
+GetBin4(N) {
+	Loop 4
+		Res := Mod(N, 2) Res, N := N >> 1
+	return, Res
+}