Question

In Assembly Language (Visual Studio 2017), create a procedure that generates a random string of Length L, containing all capital letters. When calling the procedure, pass the value of L in EAX, and pass a pointer to an array of byte that will hold the random string. Write a test program that calls your procedure 20 times and displays the strings in the console window. In your program, the random string size shall be preset as a constant.

Please include output.

Objectives:

1. Write user defined procedures
2. Call and test user defined procedures
3. Use Irvine.inc library to take input and display output. (INCLUDE Irvine32.inc)

How to See Result

You may notice that your console window will show up then quickly disappear. You have two ways to view your result from console window. One way is to set the break point at exit statement in main procedure. Another way is to add the following statement before exit statement in main procedure:

Call ReadChar

This will hold the console window to wait for your input. You can hit any key to close the console window. It is better if you add a prompt to tell user what to do. For instance: “Press any key to continue…”. To do so, you simply add

prompt BYTE “Press any key to continue…”, 0

in your .data section and add the following code before Call ReadChar:

move dx, OFFSET prompt

Call WriteString

Answer 1

.LC0:

.string "Before swapping"

.LC1:

.string "a = "

.LC2:

.string "b = "

.LC3:

.string "\nAfter swapping"

main:

push rbp

mov rbp, rsp

sub rsp, 16

mov DWORD PTR [rbp-4], 1

mov DWORD PTR [rbp-8], 2

mov esi, OFFSET FLAT:.LC0

mov edi, OFFSET FLAT:std::cout

call std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)

mov esi, OFFSET FLAT:std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)

mov rdi, rax

call std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))

mov esi, OFFSET FLAT:.LC1

mov edi, OFFSET FLAT:std::cout

call std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)

mov rdx, rax

mov eax, DWORD PTR [rbp-4]

mov esi, eax

mov rdi, rdx

call std::basic_ostream<char, std::char_traits<char> >::operator<<(int)

mov esi, OFFSET FLAT:std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)

mov rdi, rax

call std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))

mov esi, OFFSET FLAT:.LC2

mov edi, OFFSET FLAT:std::cout

call std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)

mov rdx, rax

mov eax, DWORD PTR [rbp-8]

mov esi, eax

mov rdi, rdx

call std::basic_ostream<char, std::char_traits<char> >::operator<<(int)

mov esi, OFFSET FLAT:std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)

mov rdi, rax

call std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))

lea rdx, [rbp-8]

lea rax, [rbp-4]

mov rsi, rdx

mov rdi, rax

call swap(int&, int&)

mov esi, OFFSET FLAT:.LC3

mov edi, OFFSET FLAT:std::cout

call std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)

mov esi, OFFSET FLAT:std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)

mov rdi, rax

call std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))

mov esi, OFFSET FLAT:.LC1

mov edi, OFFSET FLAT:std::cout

call std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)

mov rdx, rax

mov eax, DWORD PTR [rbp-4]

mov esi, eax

mov rdi, rdx

call std::basic_ostream<char, std::char_traits<char> >::operator<<(int)

mov esi, OFFSET FLAT:std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)

mov rdi, rax

call std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))

mov esi, OFFSET FLAT:.LC2

mov edi, OFFSET FLAT:std::cout

call std::basic_ostream<char, std::char_traits<char> >& std::operator<< <std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&, char const*)

mov rdx, rax

mov eax, DWORD PTR [rbp-8]

mov esi, eax

mov rdi, rdx

call std::basic_ostream<char, std::char_traits<char> >::operator<<(int)

mov esi, OFFSET FLAT:std::basic_ostream<char, std::char_traits<char> >& std::endl<char, std::char_traits<char> >(std::basic_ostream<char, std::char_traits<char> >&)

mov rdi, rax

call std::basic_ostream<char, std::char_traits<char> >::operator<<(std::basic_ostream<char, std::char_traits<char> >& (*)(std::basic_ostream<char, std::char_traits<char> >&))

mov eax, 0

leave

ret

swap(int&, int&):

push rbp

mov rbp, rsp

mov QWORD PTR [rbp-24], rdi

mov QWORD PTR [rbp-32], rsi

mov rax, QWORD PTR [rbp-24]

mov eax, DWORD PTR [rax]

mov DWORD PTR [rbp-4], eax

mov rax, QWORD PTR [rbp-32]

mov edx, DWORD PTR [rax]

mov rax, QWORD PTR [rbp-24]

mov DWORD PTR [rax], edx

mov rax, QWORD PTR [rbp-32]

mov edx, DWORD PTR [rbp-4]

mov DWORD PTR [rax], edx

nop

pop rbp

ret

__static_initialization_and_destruction_0(int, int):

push rbp

mov rbp, rsp

sub rsp, 16

mov DWORD PTR [rbp-4], edi

mov DWORD PTR [rbp-8], esi

cmp DWORD PTR [rbp-4], 1

jne .L6

cmp DWORD PTR [rbp-8], 65535

jne .L6

mov edi, OFFSET FLAT:std::__ioinit

call std::ios_base::Init::Init()

mov edx, OFFSET FLAT:__dso_handle

mov esi, OFFSET FLAT:std::__ioinit

mov edi, OFFSET FLAT:std::ios_base::Init::~Init()

call __cxa_atexit

.L6:

nop

leave

ret

_GLOBAL__sub_I_main:

push rbp

mov rbp, rsp

mov esi, 65535

mov edi, 1

call __static_initialization_and_destruction_0(int, int)

pop rbp

ret