43 lines
1.2 KiB
NASM
43 lines
1.2 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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; ...
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a dw 4A2Fh
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b dw 8241h
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c dw 931Dh
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d resw 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]
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and AX,0000_0000_0011_1110b
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shr AX,1
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mov BX,[b]
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and BX,0000_0111_1100_0000b
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shr BX,6
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mov CX,[c]
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and CX,1111_1000_0000_0000b
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shr CX,11
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mov DX,0
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add DX,AX
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add DX,BX
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add DX,CX
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mov [d],DX
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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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