Finding primes with sieve of Eratosthenes using assembly.

Eratosthenes.asm

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    include \masm32\include\masm32rt.inc
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comment * -----------------------------------------------------
				Johnny Vestergaard - 2011
				finding primes with sieve 
				of Eratosthenes in assembler
        ----------------------------------------------------- *

	arraySize EQU 100					; size of array to hold the prime candidates
										; (arraySize - 1) is the max prime candidate.

    .data
    array1 dd arraySize dup(0)			; initialize array.
    
    .code

start:
   
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    call main
    inkey
    exit

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main proc

    cls
      
    xor ecx, ecx					; Zero out counter
 
   fillArrayLoop:					
	   	mov eax, ecx				; Move counter value to eax
	   	add eax, 2					; The sieve starts at 2, therefore add 2 to the loop counter
	   	mov [array1+4*ecx], eax		; Insert value into array
	   	inc ecx						; Increment counter
	   	cmp ecx, arraySize			; 
	   	jb fillArrayLoop			; Jump to loop start is we are not finished
	   	
	   	
   	
   	xor ecx, ecx					; Zero out counter
   	loop1:							; This is out outer loop
		mov ebx, ecx				; Prepare ebx to be used af counter in innerloop (loop2)
		inc ebx						; Inner loop starts at ecx + 1
	   	cmp [array1+4*ecx], -1		; Value discarded?
	   	jne loop2					; if not jump to inner loop(loop2)
	   	resume1:					; Resume point
		inc ecx						; Increment out primary counter
		cmp ecx, arraySize			; Are we done?
		jb loop1					; If not jump to loop start.
		jmp theEnd					; All done!

	loop2:							; Inner loop
		cmp [array1+4*ebx], -1		; Value discarded?
		jne loop3					; if nor jump to loop3
		resume2:					; Resumt point
		inc ebx						; Increment inner loop counter
		cmp ebx, arraySize			; Are we done?
		jb loop2					; if not go to loop start.
		jmp resume1					; Loop2 dont, return to loop1.
		
	loop3:							; Here we will test if it is a prime...
		xor edx, edx				; Zero out edx
		xor eax, eax				; Zero out eax
		mov eax, [array1+4*ebx]		; Place the number we want to divite in eax
		div [array1+4*ecx]			; Divide the numbe in eax with the value from outer loop
		cmp edx, 0					; Check edx for remainder
		je nukeIt					; If we have no remainder it the number in eax is not a prime
									; therefore we nuke it. (set it to -1)
		resume3:					; Resume point
		jmp resume2					; Done, jump to resume point in loop2
		
				
   	nukeIt:
   	mov [array1+4*ebx], -1			; Not a prime, set it to -1
   	jmp resume3						; Jump to resume point
   	
   	printArrayElement:				; Just printing all the primes.
   		push ecx					; Preserve ecx
   		print str$([array1+4*ecx]), 10, 13	; Using the masm32 print macro
   		inc ebx						; Incrementing a counter used to store the number of primes.
   		pop ecx						; Callback the preserved ecx
   		jmp resumePrintArray		; Jump to resumepoint in print array.
   		
   	
   theEnd: 							; exit point
   	
   	
   	xor ecx, ecx					; Zero out.
   	xor ebx, ebx					; Zero out.

   	printArray:					
   		cmp [array1+4*ecx], -1		; Check if we have a prime.
   		jne printArrayElement		; If we have jump to printArrayElement.
   		resumePrintArray:			; Resume point
   		inc ecx						; Incrementing
   		 cmp ecx, arraySize			; Are we done?
   		jb printArray				; If not jump to printArray...

	print "Number of primes below "
	print str$(arraySize)
	print ": "
	print str$(ebx), 10, 13

    ret

main endp

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end start