Assembly x64 Intro - Logic Operate

; intlogic_64.asm show some simple C code and corresponding nasm code

; the nasm code is one sample, not unique

;

; compile: nasm -f elf64 -l intlogic_64.lst intlogic_64.asm

; link: gcc -m64 -o intlogic_64 intlogic_64.o

; run: ./intlogic_64 > intlogic_64.out

;

; the output from running intlogic_64.asm and intlogic.c is

; c=5 , a=3, b=5, c=15

; c=a&b, a=3, b=5, c=1

; c=a|b, a=3, b=5, c=7

; c=a^b, a=3, b=5, c=6

; c=~a , a=3, b=5, c=-4

;

;The file intlogic_64.c is:

; #include <stdio.h>

; int main()

; {

; long int a=3, b=5, c;

;

; c=15;

; printf("%s, a=%ld, b=%ld, c=%ld\n","c=5 ", a, b, c);

; c=a&b; /* and */

; printf("%s, a=%ld, b=%ld, c=%ld\n","c=a&b", a, b, c);

; c=a|b; /* or */

; printf("%s, a=%ld, b=%ld, c=%ld\n","c=a|b", a, b, c);

; c=a^b; /* xor */

; printf("%s, a=%ld, b=%ld, c=%ld\n","c=a^b", a, b, c);

; c=~a; /* not */

; printf("%s, a=%ld, b=%ld, c=%d\n","c=~a", a, b, c);

; return 0;

; }

extern printf ; the C function to be called

%macro pabc 1 ; a "simple" print macro

section .data

.str db %1,0 ; %1 is first actual in macro call

section .text

mov rdi, fmt ; address of format string

mov rsi, .str ; users string

mov rdx, [a] ; long int a

mov rcx, [b] ; long int b

mov r8, [c] ; long int c

mov rax, 0 ; no xmm used

call printf ; Call C function

%endmacro

section .data ; preset constants, writable

a: dq 3 ; 64-bit variable a initialized to 3

b: dq 5 ; 64-bit variable b initializes to 4

fmt: db "%s, a=%ld, b=%ld, c=%ld",10,0 ; format string for printf

section .bss ; unitialized space

c: resq 1 ; reserve a 64-bit word

section .text ; instructions, code segment

global main ; for gcc standard linking

main: ; label

push rbp ; set up stack

lit5: ; c=5;

mov rax,15 ; 5 is a literal constant

mov [c],rax ; store into c

pabc "c=5 " ; invoke the print macro

andb: ; c=a&b;

mov rax,[a] ; load a

and rax,[b] ; and with b

mov [c],rax ; store into c

pabc "c=a&b" ; invoke the print macro

orw: ; c=a-b;

mov rax,[a] ; load a

or rax,[b] ; logical or with b

mov [c],rax ; store into c

pabc "c=a|b" ; invoke the print macro

xorw: ; c=a^b;

mov rax,[a] ; load a

xor rax,[b] ; exclusive or with b

mov [c],rax ; store result in c

pabc "c=a^b" ; invoke the print macro

notw: ; c=~a;

mov rax,[a] ; load c

not rax ; not, complement

mov [c],rax ; store result into c

pabc "c=~a " ; invoke the print macro

pop rbp ; restore stack

mov rax,0 ; exit code, 0=normal

ret ; main returns to operating system

c=5 , a=3, b=5, c=15

c=a&b, a=3, b=5, c=1

c=a|b, a=3, b=5, c=7

c=a^b, a=3, b=5, c=6

c=~a , a=3, b=5, c=-4