callingFunctions.S

1. callingFunctions.S Passing arguments to functions via the stack
2. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 8(%esp) argv 4(%esp) argc (%esp) return addr %esp 28ff2c %ebp old %ebp %eax $0
3. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 8(%esp) argv 4(%esp) argc (%esp) return addr %esp 28ff2c %ebp old %ebp %eax $0
4. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 12(%esp) argv 8(%esp) argc 4(%esp) return addr (%esp) old %ebp %esp 28ff28 %ebp old %ebp %eax $0
5. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 12(%esp) argv 8(%esp) argc 4(%esp) return addr (%esp) old %ebp %esp 28ff28 %ebp old %ebp %eax $0
6. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp %esp 28ff28 %ebp 28ff28 %eax $0
7. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp %esp 28ff28 %ebp 28ff28 %eax $0
8. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp %esp 28ff20 %ebp 28ff28 %eax $0
9. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp %esp 28ff20 %ebp 28ff28 %eax $0
10. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax $0
11. LC0: .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax $0
12. .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax $0
13. .ascii "The argument was %d\12\0" .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax $0
14. .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax $0
15. .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax argv
16. .text .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax argv Address of pointer to prog name
17. .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax argv Address of pointer to prog name
18. .globl _main .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax argv+4 Address of pointer to first arg
19. .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax argv+4 Address of pointer to first arg
20. .def _main; .scl 2; .type 32; .endef _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax argv[1] pointer to first arg
21. _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) %esp 28ff00 %ebp 28ff28 %eax argv[1]
22. _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax argv[1]
23. _main: pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax For our purposes argv[1] = "67" 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax argv[1]
24. pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) For our purposes argv[1] = "67" 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax argv[1]
25. pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) For our purposes argv[1] = "67" _atoi grabs the char array at the address stored in (%esp), converts the ASCII string to an int, and returns the int in %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax argv[1]
26. pushl %ebp movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) For our purposes argv[1] = "67" _atoi grabs the char array at the address stored in (%esp), converts the ASCII string to an int, and returns the int in %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax $67
27. movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $1234 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax $67
28. movl %esp, %ebp andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax $67
29. andl $-16, %esp subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax $67
30. subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax $67
31. subl $32, %esp call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) $67 (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax $67
32. call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) $67 (%esp) argv[1] %esp 28ff00 %ebp 28ff28 %eax $67
33. call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) $67 (%esp) $LC0 %esp 28ff00 %ebp 28ff28 %eax $67
34. call ___main movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) $67 (%esp) $LC0 $LC0 is the location in memory of our format string. "The argument was %d\12\0" %esp 28ff00 %ebp 28ff28 %eax $67
35. movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave ret 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) $67 (%esp) $LC0 %esp 28ff00 %ebp 28ff28 %eax $67 $LC0 is the location in memory of our format string. "The argument was %d\12\0"
36. movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave ret 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) $67 (%esp) $LC0 %esp 28ff00 %ebp 28ff28 %eax $67
37. movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave ret 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) $67 (%esp) $LC0 %esp 28ff00 %ebp 28ff28 %eax $0
38. movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave ret 12(%ebp) argv 8(%ebp) argc 4(%ebp) return addr (%ebp) old %ebp 28(%esp) $67 24(%esp) 20(%esp) 16(%esp) 12(%esp) 8(%esp) 4(%esp) $67 (%esp) $LC0 %esp 28ff00 %ebp 28ff28 %eax $0
39. movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave ret 8(%esp) argv 4(%esp) argc (%esp) return addr %esp 28ff2c %ebp old %ebp %eax $0
40. 8(%esp) argv 4(%esp) argc (%esp) return addr %esp 28ff2c %ebp old %ebp %eax $0 movl $1234, 28(%esp) movl 12(%ebp), %eax addl $4, %eax movl (%eax), %eax movl %eax, (%esp) call _atoi movl %eax, 28(%esp) movl 28(%esp), %eax movl %eax, 4(%esp) movl $LC0, (%esp) call _printf movl $0, %eax leave ret
41. callingFunctions.S Passing arguments to functions via the stack This presentation by Pat Hawks is licensed under a Creative Commons Attribution 4.0 International License