Luhn validation algorithm

Hello, I needed a modified version of Luhn Algorithm into one installer and I didn't see anything similar on the wiki/forum, so here's the validation algorithm, it might be useful for someone.
The example needs NSISArray and PassDialog to work.
My 2 cents...

Name    "Luhn_Algorithm"

OutFile "Luhn_Algorithm.exe"



## Include headers

!include MUI.nsh

!include NSISArray.nsh



## Pages

Page Custom NumberPageShow NumberPageLeave

!insertmacro MUI_PAGE_COMPONENTS

!insertmacro MUI_PAGE_INSTFILES



## Languages

!insertmacro MUI_LANGUAGE English



Var Checksum

Var Numbers



Function NumberPageShow

 !insertmacro MUI_HEADER_TEXT "Luhn algorithm validation" ""



 PassDialog:😁ialog Serial           \

                    /HEADINGTEXT "Enter the number that you want to check." \

                    /CENTER             \

                    /BOXDASH 62  70 4 '' \

                    /BOXDASH 142 70 4 ''  \

                    /BOXDASH 222 70 4 ''   \

                    /BOX     302 70 4 ''



 Pop $R0 

FunctionEnd 



Function NumberPageLeave

	Pop $R0

	Pop $R1

	Pop $R2

	Pop $R3		

                                             

	StrCpy $Numbers $R0$R1$R2$R3         

	Goto checkKey

	

	checkKey:

	${Array} array 9 3

	${ArrayFunc} WriteList

	${ArrayFunc} Read

	${array->Init}	

	StrCpy $Checksum "0"  

	${array->WriteList} '"0" "1" "2" "3" "4" "-4" "-3" "-2" "-1" "0"' 

	StrCpy $R6 15   # Numbers length - 1

	${Do}                                                              

	  StrCpy $0 "$R0$R1$R2$R3" 1 $R6                                                                                 

	  IntOp $Checksum $Checksum + $0                                   

	  Math::script "a = $R6; b = 16; c = 2; r9 = a; r1 = b; r2 = c; z = ((a - b) % c); r4 = #[z == 0, 'Valid', 'Invalid']"

	  ${If} $4 == 'Valid'                                              

	    ${array->Read} $R7 $0

		IntOp $Checksum $Checksum + $R7                                

	  ${EndIf}

	  IntOp $R6 $R6 - 1

	${LoopUntil} $R6 = -1		

	${array->Delete}

	Math::script "a = $Checksum; b = 10; r0 = a; r1 = b; z = a % b; r2 = #[z == 0, 'Valid', 'Invalid']"

	

	${If} $2 == 'Valid'

		Goto success

    ${Else}

		Goto returnError

	${EndIf}

	

	returnError:

	MessageBox MB_OK|MB_ICONEXCLAMATION "Wrong number"

    Abort



	success:

FunctionEnd



Section "dummy"



SectionEnd

I'll try to write Verhoeff now.

See you.