Code Trouble

[GregL]

Hey etow,

Please use Code Tags when posting code. You can use the 'Insert Code' button or just put in the tags manually.

[etow]

Yes, thanks

All my problems are solved.

[GregL]

Keep at it etow.  :U 

[etow]

Here is my final code in zip file.

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[RuiLoureiro]

Etow,
           I want to say that i am not a programmer and i am not young.
           Are you a mathematics student ? You have some troubles with Math.

; This code should be:           

Code Select Expand


.While Factor <= Esi      ; while Factor less than or equal to (Number = Esi)
Mov Eax, Number     ; set Eax = Number
Mov Ebx, Factor       ; set Ebx = Factor
Cdq                        ; convert to double quad word or 64-bit long word
Div   Ebx                 ; Eax = Eax / Ebx
Mov Quotient, Eax    ; set Quotient = Eax
                              ; Quotient = Number / Factor

;                  Mov Eax, Number     ; set Eax = Number
;                  Cdq                 ; convert to double quad word or 64-bit long word
;                  Mov Ebx, Factor     ; set Ebx = Factor
;                  Div Ebx             ; Eax = Eax / Ebx, Edx contains the remainder

            Do you believe you need to divide EDX:EAX 2 times, one to get
            the quotient and the other to get the remainder ? Why ? And
            then, why do you believe we need to do it one more time ? Why ?
            This is the case here:

; This code should be:           

Code Select Expand


Inc primeCounter        ; primeCounter = primeCounter + 1
                               ; generate PrimeFactor string by
                               ; concatenating prime factors and
                               ; adding them to PrimeFactor string
Mov Esi, Quotient       ; set Esi = Quotient
Mov Number, Esi         ; Esi = Number = Quotient
;                Mov Edi, Quotient       ; set Edi = Quotient
;                Mov Number, Edi         ; Edi = Number = Quotient             
;                Mov Eax, Number         ; set Eax = Number
;                Mov Ebx, Factor     ; set Ebx = Factor
;                Cdq                 ; convert to double quad word or 64-bit long word
;                Div Ebx             ; Eax = Eax / Ebx
;                Mov Quotient, Eax   ; set Quotient = Eax
                           ; Quotient = Number / Factor
                           ;    Mov Remainder, Edx  ; set Remainder = Edx


            I try to explain: you want to get Factor *** While Factor <= Esi ***
                              where ESI is the Number to be factored.
                       
            Look at this example:  Number=70, Factor=2 (at the begining). ESI=70.
           
                           Number               Factor
            Now, begin:     70      divided by    2     quotient=35     remainder=0

            It means:   70 = 2 * 35 and means also that to get the next factor of 70
                                    we need to get the factors of the Number=35
                                    and we begin with the same Factor=2;
            ;.......................................................................
            Now we want to get the factors of 35, so Number=35, ESI=35, Factor=2

                           Number               Factor
            Next step:       35      divided by    2     quotient=???    remainder=not 0
                             35                    3             =???             =not 0
                             35                    4             =???             =not 0
                             35                    5     quotient=7      remainder= 0

            It means:   35 = 5 * 7 and means also that to get the next factor
                                    we need to use the Number=7 and the same Factor=5;
                                   
            Then:   70 = 2 * 35 = 2 * 5 * 7 because 35 = 5 * 7
            ;.........................................................................
            Now we want to get the factors of 7, so Number=7, ESI=7, Factor=5

                           Number               Factor
            Next step:       7      divided by    5     quotient=???    remainder=not 0
                             7                    6             =???             =not 0
                             7                    7     quotient= 1    remaider= 0
           
            It means:   7 = 7 * 1 and means also that to get the next factor
                                  we need to use the Number=1 and the same Factor=7;
                                  ESI should be =1, too.

            Then:   70 = 2 * 5 * 7.
                                     
            Now stop because Factor is not less than or equal ESI (ESI=1 and Factor=7).

            Isnt it?
RuiLoureiro           

[etow]

Hi RuiLoureiro,

Sorry I have not cleaned the code properly.
No, I do not have problems with math.  I do well with math.
I think I have difficulty visualizing using assembly language instructions to get the math to work properly, that is all.

[etow]

Here is the algorithm to get the prime factorization:

Code Select Expand


PrimeFactor = " "
Factor = 2

Do while (Factor <= Number)
   Quotient = Number / Factor
   Remainder = Number mod Factor

   If (Remainder = 0) then
          .If (primeCounter = 1) ; if primeCounter equals to 1
              PrimeFactor = concat(PrimeFactor, Factor)
              ; insert the first prime factor to the PrimeFactor string
           .ElseIf (primeCounter > 1) ; if primeCounter greater than 1
                PrimeFactor = concat(PrimeFactor, " x ", Factor)
                ; concatenate additional prime factors to the PrimeFactor string
            .EndIf
           Number = Quotient
           Quotient = Number / Factor
           Remainder = Number mod Factor
   Else
      Factor = Factor + 1
   EndIf
Loop


[etow]

Here is my edited final code.



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[etow]

Sorry I forgot to mention how to increment primeCounter.

Here is the revised algorithm to do prime factorization:

Code Select Expand



primeCounter = 1
PrimeFactor = " "
Factor = 2

Do while (Factor <= Number)
   Quotient = Number / Factor
   Remainder = Number mod Factor

   If (Remainder = 0) then

          .If (primeCounter = 1) then ; if primeCounter equals to 1
              PrimeFactor = concat(PrimeFactor, Factor)
              ; insert the first prime factor to the PrimeFactor string
           .ElseIf (primeCounter > 1) then ; if primeCounter greater than 1
                PrimeFactor = concat(PrimeFactor, " x ", Factor)
                ; concatenate additional prime factors to the PrimeFactor string
            .EndIf

           Number = Quotient
           Quotient = Number / Factor
           Remainder = Number mod Factor

           primeCounter = primeCounter + 1           
   ElseIf
      Factor = Factor + 1
   EndIf
Loop



[etow]

Reminder:

Number is a positive integer greater or equal to 2.

[etow]

Another version of prime factorization but with a procedure call :



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