45 lines
1.4 KiB
NASM
45 lines
1.4 KiB
NASM
bits 32 ; assembling for the 32 bits architecture
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; declare the EntryPoint (a label defining the very first instruction of the program)
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global start
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; declare external functions needed by our program
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extern exit ; tell nasm that exit exists even if we won't be defining it
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import exit msvcrt.dll ; exit is a function that ends the calling process. It is defined in msvcrt.dll
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; msvcrt.dll contains exit, printf and all the other important C-runtime specific functions
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; our data is declared here (the variables needed by our program)
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segment data use32 class=data
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a dd 1
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b db 1
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c dw 1
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d dw 1
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x resd 1
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; our code starts here
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segment code use32 class=code
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start:
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mov ax,[a] ;AX=a-low
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mov dx,[a+2] ;DX=a-high DX:AX=a-low
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mov bx,2 ;BX=2
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idiv bx ;AX=a/2
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mov dx,ax ;DX=a/2
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mov al,[b] ;AL=b
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mov bl,3 ;BL=3
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imul bl ;AX=b*3
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add dx,ax
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mov ax,[c]
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imul word [d]
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push dx
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push ax
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pop eax
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mov eax,ecx
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mov ax,dx
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cwde
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sub eax,ecx
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add eax,100
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mov [x],eax
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; exit(0)
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push dword 0 ; push the parameter for exit onto the stack
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call [exit] ; call exit to terminate the program
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