; This is an implementation of the ripple carry adder
; http://en.wikipedia.org/wiki/Adder_(electronics)#Ripple_carry_adder

#include <Math.au3>
#include <String.au3>

; using strings for simple user input
Dim $numA =   "00001001" ; 9
Dim $numB = "11111100" ; -4

; Try a big value, such as 11111111
; And add a value 1 to it, so overflow will occur
; $numA = "11111111"
; $numB = "00000001"

; Gets the longest string of the two and turns them into a binary array like: [1,0,1,1]
Dim $len = _LongestString($numA,$numB)
; Alternatively you can set this to a number like 8 to indicate the number of full adders to use
$len = 8 ; 16 bits full adder

Dim $binA = _BinStringToBinArray($numA, $len)
Dim $binB = _BinStringToBinArray($numB, $len)

; Makes a variable for the result number
Dim $sum[$len]
Dim $carry = 0

For $i = 0 to $len-1
	$res = _FullAdder( $binA[$i], $binB[$i], $carry )
	
	$sum[$i] = $res[0]
	$carry = $res[1]
Next

If ( $carry == 1 ) Then ; Overflow 
	MsgBox(0,"AutoIt Implementation of Full Adder","Overflow has occured, your results will not be accurate.")
EndIf

MsgBox(0, "AutoIt Implementation of Full Adder", "Result: " & _BinArrayToBinString($sum) )

;; Utility function for IO

; Turns a string "1011" into a 'binary array' : [1,0,1,1]
Func _BinStringToBinArray($in, $len = 8)
	$in = _StringReverse($in) ; it would've been easier to switch the MSB and LSB but whatever
	
	Local $t = StringSplit($in,"")
	Local $ret[$len]
	
	For $i = 0 to $len-1
		$ret[$i] = 0
	Next
	
	For $i = 1 to UBound($t)-1
		$ret[$i-1] = Number($t[$i])
	Next
	
	Return $ret
EndFunc

; Turns a string "1011" into a 'binary array' : [1,0,1,1]
Func _BinArrayToBinString($in)
	Local $ret = ""
	For $i = UBound($in)-1 to 0 Step -1
		$ret &= String($in[$i])
	Next
	Return $ret
EndFunc

; Returns the length of the longest string
Func _LongestString($a,$b)
	Return _Max(StringLen($a),StringLen($b))
EndFunc

;; Binary mathematical functions

; http://en.wikipedia.org/wiki/Adder_(electronics)#Full_adder
Func _FullAdder($a, $b, $cIn = 0)
	Local $cOut = BitOR( BitAND($a,$b) , BitAND($cIn, BitXOR($a,$b)))
	Local $S = BitXOR(BitXOR($a,$b),$cIn)
	local $ret[2] = [$S,$cOut]
	Return $ret
EndFunc

; http://en.wikipedia.org/wiki/Adder_(electronics)#Half_adder
Func _HalfAdder($a,$b)
	Local $S = BitXOR($a,$b) ; sum
	Local $C = BitAND($a,$b) ; carry
	local $ret[2] = [$S,$C]
	Return $ret
EndFunc