Скачать или смотреть Computer Architecture: x86 in-line Assembly in C

How to write in-line x86 Assembly code in C

For the complete lecture series, please visit:
http://www.stallinga.org/Youtube/Comp...

The C program:

/********************************************
file: asm.c *
How to use in-line x86 Assembly in C *
gcc -no-pie -masm=intel asm.c *
./a.out *
********************************************/

#include stdio.h ; // add angled brackets here (not allowed on Youtube)

int a, b; // global vars are on the heap

int foo(int x){ // arguments are on the stack
int i = 4; // local vars too
asm("mov rax, [rsp-20]"); // int x;
asm("mov rcx, [rsp-4]"); // int i;
asm("mul rcx"); // rax = i*x;
asm("mov rcx, [a]"); // global int a;
asm("mul rcx"); // rax = a*i*x;
asm("mov rcx, [b]"); // global int b;
asm("mul rcx"); // rax = b*a*i*x;
// return value is in rax
// stack adjusted by gcc and 'ret' is added by gcc
}

void printstring(char *q){
asm("mov rsi, [rsp-8]"); // q*
asm("mov rax, 1");
asm("mov rdi, 1");
asm("mov rdx, 0xD");
asm("syscall");
// stack adjusted by gcc and 'ret' is added by gcc
}

int main(int argc, char **argv){
char p[] = "Hello world!\n";
int y;

a = 10; b = 2;
y = foo(3);
printstring(p);
printf("foo return value: y = %d\n", y);

return 0;
}