Question

Take the following program and translate it into PEP/9 assembly language:

#include <iostream>

using namespace std;

int theArray[] = { 5, 11, -29, 45, 9, -1};

void sumPos(int ary[], int len, int &sum)

{

   sum = 0;

   for (int i = 0; i < len; i++)

           if (ary[i] > 0)

               sum = sum + ary[i];

}

int main()

{

   int total;

   sumPos(theArray, 6, total);

   for (int k=0; k < 6; k++)

     cout << theArray[k] << endl;

cout << "Positive sum is " << total << endl;

   return 0;

}

You must use equates to access the stack and the index register in accessing the array. Remember, the sumPos array does NOT know about the global "theArray" – the address of the array must be passed via the parameter.

ANSWER HAS TO BE IN Pep/9. please.

Answer 1

• theArray:

  .long 5

  .long 11

  .long -29

  .long 45

  .long 9

  .long -1

  sumPos(int*, int, int&):

  push rbp

  mov rbp, rsp

  mov QWORD PTR [rbp-24], rdi

  mov DWORD PTR [rbp-28], esi

  mov QWORD PTR [rbp-40], rdx

  mov rax, QWORD PTR [rbp-40]

  mov DWORD PTR [rax], 0

  mov DWORD PTR [rbp-4], 0

  .L4:

  mov eax, DWORD PTR [rbp-4]

  cmp eax, DWORD PTR [rbp-28]

  jge .L5

  mov eax, DWORD PTR [rbp-4]

  cdqe

  lea rdx, [0+rax*4]

  mov rax, QWORD PTR [rbp-24]

  add rax, rdx

  mov eax, DWORD PTR [rax]

  test eax, eax

  jle .L3

  mov rax, QWORD PTR [rbp-40]

  mov edx, DWORD PTR [rax]

  mov eax, DWORD PTR [rbp-4]

  cdqe

  lea rcx, [0+rax*4]

  mov rax, QWORD PTR [rbp-24]

  add rax, rcx

  mov eax, DWORD PTR [rax]

  add edx, eax

  mov rax, QWORD PTR [rbp-40]

  mov DWORD PTR [rax], edx

  .L3:

  add DWORD PTR [rbp-4], 1

  jmp .L4

  .L5:

  nop

  pop rbp

  ret

  .LC0:

  .string "Positive sum is "

  main:

  push rbp

  mov rbp, rsp

  sub rsp, 16

  lea rax, [rbp-8]

  mov rdx, rax

  mov esi, 6

  mov edi, OFFSET FLAT:theArray

  call sumPos(int*, int, int&)

  mov DWORD PTR [rbp-4], 0

  .L8:

  cmp DWORD PTR [rbp-4], 5

  jg .L7

  mov eax, DWORD PTR [rbp-4]

  cdqe

  mov eax, DWORD PTR theArray[0+rax*4]

  mov esi, eax

  mov edi, OFFSET FLAT:_ZSt4cout

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

  mov esi, OFFSET FLAT:_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_

  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> >&))

  add DWORD PTR [rbp-4], 1

  jmp .L8

  .L7:

  mov esi, OFFSET FLAT:.LC0

  mov edi, OFFSET FLAT:_ZSt4cout

  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:_ZSt4endlIcSt11char_traitsIcEERSt13basic_ostreamIT_T0_ES6_

  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

  __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 .L12

  cmp DWORD PTR [rbp-8], 65535

  jne .L12

  mov edi, OFFSET FLAT:_ZStL8__ioinit

  call std::ios_base::Init::Init() [complete object constructor]

  mov edx, OFFSET FLAT:__dso_handle

  mov esi, OFFSET FLAT:_ZStL8__ioinit

  mov edi, OFFSET FLAT:_ZNSt8ios_base4InitD1Ev

  call __cxa_atexit

  .L12:

  nop

  leave

  ret

  _GLOBAL__sub_I_theArray:

  push rbp

  mov rbp, rsp

  mov esi, 65535

  mov edi, 1

  call __static_initialization_and_destruction_0(int, int)

  pop rbp

  ret