prime # assembly language program

I am learning assembly language and need some help in figureing out how to get this program to display only prime numbers from 2 to 19. please help /prog/

; prime.asm
; sample program to demonstrate procedures
; calulates and prints prime numbers from 1 to 20

include 'emu8086.inc'

org  100h ; set location counter to 100h

jmp CodeStart

DataStart:
   max dw 19
   space db " ", 0

CodeStart:
   mov bx, 2
  
   LoopStart:
      
       ; must be a prime
       mov ax, bx
       call print_num
      
       ; print a space
       mov si, offset space
       call print_string
      
       add bx, 1
       cmp bx, max

   jle LoopStart
  
   ret

   IsPrime PROC
       ; uses a loop to determine if number in bx is prime
       ; upon return if bx not prime dx will be 0, otherwise dx > 0

       ; we only have to test divisors from 2 to bx/2
      
       ; prepare to divide dx:ax / 2
       mov ax, bx        
       mov dx, 0
       mov cx, 2 
       div cx
      
       ; move result into si for loop
       mov si, ax
      
       ; assume the value is prime
       mov dx, 1
      
       ; start loop at 2
       mov cx, 2
      
       PrimeLoop:
      
           ; compare loop count(in cx) and max loop value (in si)
           cmp cx, si
          
           ; jump out of loop if count(cx) > si
           ja StopLabel
      
           ; divide test value (in bx) by loop count (in cx)
           mov ax, bx
           mov dx, 0           
           div cx
          
           ; check remainder (in dx), if zero then we found a divisor
           ; and the number cannot be prime
           cmp dx, 0
          
           ; if dx = 0 then we found a divisor and can stop looking
           je StopLabel
          
           ; increment count
           add cx, 1
      
       jmp PrimeLoop
      
       StopLabel:
      
       ret
   IsPrime ENDP
  
DEFINE_PRINT_STRING
DEFINE_SCAN_NUM
DEFINE_PRINT_NUM
DEFINE_PRINT_NUM_UNS

Assemble it

write it in c, compile it, assemble it, run it

If you are confused, apply labels to your registers.  Reading back your code will make a lot more sense. Also, write pseudocode first.

Not that I know my x86 ASM, but it looks like your code here will print the numbers 2-20, then exit the program.

; prime.asm
; sample program to demonstrate procedures
; calulates and prints prime numbers from 1 to 20

include 'emu8086.inc'

org  100h ; set location counter to 100h

jmp CodeStart

DataStart:
   primes db "2 3 5 7 11 13 17 19", 0

CodeStart:
   mov si, offset primes
   call print_string

   ret


;CALCULATE AND PRINT PRIMES 1-20
FACTORS .DB 0
DIVDEND .DB 0
NUMBER  .DB 0
INTMAIN LDY #20
NEXT    TYA
        PHA ;save .A
        JSR ISPRIME ;sets Z if prime
        PLA ;restore .A
        BNE AINT
        ;[.A here will have a prime number]
        ;[Depending on architecture, insert print routine here]
        ;[Note, convert to ASCII (or unicore) first
        NOP
AINT    ;[if you want do something for non primes, put it here]
        DEY
        BPL NEXT
        RTS
ISPRIME ;number to be tested in A
        LDA #0
        STA FACTORS
        TAX
        DEX ;don't bother dividing by itself
        STA NUMBER ;save it because DIVTEST destroys .A
NEXT    LDA NUMBER
        JSR DIVTEST
        BNE ISNT
        INC FACTORS
ISNT    DEX
        CMP #1 ;don't bother dividing by 1
        BNE NEXT
        LDA FACTORS
        CMP #1
        RTS
DIVTEST ;divide A by X, set Z if even
        ;division by 0 results in infinite loop
        ;.A is destroyed, so save it if you need it
        STA DIVDEND
        TXA
DIVLOOP SBC DIVDEND
        BPL DIVLOOP
        LDA DIVDEND
        RTS

>>6
how do i converted to unicore

>>6
Oh wow, nostalgia

Wait what? BNE? is this ARM?

bump if not equal

>>9
It's 6502.  The designers of the ARM instruction set were fans of the 6502 and borrowed a lot of syntax conventions from it.

>>11
Kudos.  I would have avr'd the fucker. Here's hoping his assignment is in x86.

>>11
Yep, that's because the project originally started at Acorn, in fact ARM originally stood for Acorn RISC Machine. Acorn were the creators of the BBC Micro range of machines which used the 6502 chip.

I was surprised to learn that the original designer of the ARM chip is a male to female transsexual

>>14
Can you believe it?

>>14
Computer science tends to have more than its fair share of M2F trannies, some other examples include Lynn Conway, Joanna Rutkowska and Jeri Ellsworth.

>>16
My theory is that most people who succeed in the Computer Science fields tend to be the girly, nerdy type who used to get picked on in school.

>>17
TRU.DAT

>>17
Nah, HR makes them do it to even the gender ratio. A quick slash with the scalpel, and suddenly you're an equal opportunity employer.

It's the only way programmers can reproduce.

Assembler eh?

i swore i would never use it again

>>16

Um, I don't think Jeri was a male at any point...

>>22
Then you think incorrectly

http://en.wikipedia.org/wiki/David_Reimer

^disgust_ing