I need help writing these functions in assembly language. They are written in C language 

1. int sub2(int a, int b)

{

return a - b;

}

2. int sub3(int a, int b)

{

return sub2(sub2(a, b), c);

}

3. void mystrcpy(char* dst, char* src);

4. int calc(int x, int y, int z)

{

return x * y + z x;

}