Problem 1
a) Write a complete program that will prompt the user for person records and save all the entered records into a file specified in the command line. Note that you should save all the records as binary C-structs in the data file. You also do not need to do error checking on input data. The following gives an example of how to run the program and enter the data.

>prob2 datafile
Enter record (y/n): y
Name: Ayse Cemal
Age:  32
Enter record (y/n): y
Name: Ali Cemal
Age:  33
Enter record (y/n): n

b) What will be the output of the following program ?

#include <stdio.h>

main()
{
   int a[3][3] = {1,2,3,4,5,6,7,8,9} ; 
   int *p, *q ; 

   p = a[0] ; 
   q = *a ; 
   printf("%d %d \n",p[1],q[2]) ; 

   p = a[1] ; 
   q = *(a+1) ; 
   printf("%d %d \n",p[1],q[2]) ; 
}

Problem 2
Consider the C program:

/******** C program *********/
#include <stdio.h>

func()
{
   int a,b,c ;
   register int d ;

   a = -4 ;
   b = -8 ;
   c = a + b ;
   d = c + a ;
   /* HERE */
}

main()
{
   short x ;

   x = -4 ;
   func() ;
}

        .file   "exq.c"
        .version        "01.01"
gcc2_compiled.:
.text
        .align 4
.globl func
        .type    func,@function
func:
        pushl %ebp
        movl %esp,%ebp
        subl $12,%esp
        movl $-4,-4(%ebp)
        movl $-8,-8(%ebp)
        movl -4(%ebp),%edx
        addl -8(%ebp),%edx
        movl %edx,-12(%ebp)
        movl -12(%ebp),%eax
        addl -4(%ebp),%eax
.L1:
        leave
        ret
.Lfe1:
        .size    func,.Lfe1-func
        .align 4
.globl main
        .type    main,@function
main:
        pushl %ebp
        movl %esp,%ebp
        subl $4,%esp
        movw $-4,-2(%ebp)
        call func
.L2:
        leave
        ret
.Lfe2:
        .size    main,.Lfe2-main
        .ident  "GCC: (GNU) 2.7.2.3"

Answer the following questions about the above programs:

1. Circle and name all the references to the C variables a,b,c,d and x on the assembly code.
2. Draw the memory layout of the program when it reaches the point marked as /* HERE */ during its execution. On the diagram show memory locations of all the variables and the contents of the registers (if you do not know the exact contents, you can show where they point to in the memory diagram).

Problem 3
State whether True or False:

(a)

The following piece of code segment will lead to runtime error:

       int *p, *q ;
       p = (int *) malloc(10*sizeof(int)) ;
       q = &(p[2]) ;
       free(&(q[-2])) ;

(b)

The following two function prototypes are equivalent:

       void func(int a[][5])  ;

       void func(int (*a)[5]) ;

(c)

The contents of the CS register can be updated in x86 assembly language programs.

(d)

In x86, the zero flag (ZF) indicates that the last CPU operation resulted in a quantity that contains all binary 0s.

(e)

There is no boolean type in C.

(f)

089 is an octal number in C language.

(g)

If the static keyword (modifier) appears in front of a function definition, then the scope of the function is limited to the file in which it is defined.

(h)

A procedure in C is written as a function which has void as the return type.

(i)

A void pointer can be dereferenced in C.

(j)

Automatic variables with explicit initializers are always initialized when a function is entered in C.

Problem 4
Answer all of the following short questions about 8086.

(a)

Give an example of instruction for each of the following addressing modes and state an advantage and disadvantage for each of them: (i) Immediate addressing, (ii) Register indirect.

(b)

How many bytes are adressible by 8086 ?

(c)

If the CS register contains the number B000h, and the IP contains the number ABCDh, what is the address of the instruction ?

(d)

Execute the following program line by line. Show the contents of all the affected registers after executing each line. You should express your answer using hexadecimal numbers.

            MOV  AX,513d
            MOV  CL,3d
            DIV  CL

(e)

Execute the following program line by line. Show the contents of all the affected registers after executing each line. You should express your answer using hexadecimal numbers.

            MOV   DX,1d
            MOV   AX,8d
            MOV   CX,8d
            MUL   CX

code segment 
         mov   bp,arry
         mov   bx,arry
         mov   ah,____  ;  /*  (a)   */
input:   int   21h
         cmp   al,10d   ;  read string until newline 
         je    testpal  
         mov   ____,al  ;  /*  (b)   */
         inc   bp 
         jmp   input
testpal:
         dec   bp
         mov   dl,'n'
begloop: cmp   bx,bp
         jae   ispal    ;  it is palindrome
         mov   cl,____     /*  (c)   */
         cmp   cl,____     /*  (d)   */
         jne   notpal   ; not a palindrome 
         inc   ____     ;   /*  (e)   */
         dec   bp 
         ___   ____        /* (f) (g) */
ispal:   mov   ____,'y' ;  /* (h)     */
notpal:  mov   ____,02h ;  /* (i)     */
         ___   21h      ;  /* (j)     */
finish:  int   20h 
arry:    
         db    ? 
code ends 

Problem 6
Consider the following C program which generates prime numbers:

/**************************************************************/
#include <stdio.h>

main()
{
     int prime[50] ;
     int j ; 
     int k ;
     int n ; 
     int quo,rem ; 


P1:  prime[0] = 2 ; 
     n  = 3 ; 
     j  = 0 ; 
P2:  j  = j+1 ; 
     prime[j] = n ; 
P3:  if (j == 49) goto P9 ;
P4:  n = n + 2 ; 
P5:  k = 1 ; 
P6:  quo = n / prime[k] ; 
     rem = n % prime[k] ; 
     if (rem == 0) goto P4 ; 
P7:  if (quo <= prime[k]) goto P2 ; 
P8:  k = k+1 ; 
     goto P6 ; 
P9:  for(j=0 ; j < 50 ; j++) printf("%d ",prime[j]) ; 
}
/**************************************************************/

The following x86 program generates the 50 prime numbers using the same algorithm as the above C-program. Some instructions/operands have been intentionally left blank.

code segment
;;;;;;;;;;;;;;;;;;;;;;;;;;
; PART 1: Generate primes;
;;;;;;;;;;;;;;;;;;;;;;;;;;
P1:  mov    bx,prime
     mov    ___,2d         ; /* (a)               */
     mov    si,3
     mov    cx,0
P2:  inc    cx
     add    bx,2
     mov    w[bx],___      ; /* (b)               */
P3:  cmp    cx,49
     ____________          ; /* (c)               */
P4:  ____________          ; /* (d)               */
P5:  mov    bp,prime
     add    bp,2
P6:  ____________          ; /* (e)               */
     xor    dx,dx
     div    w[bp]
     ____________          ; /* (f)               */
     je     P4
P7:  cmp    w[bp],___      ; /* (g)               */
     jae    P2       
P8:  add    bp,___         ; /* (h)               */
     jmp    P6
;;;;;;;;;;;;;;;;;;;;;;
;PART 2: PRINT PRIMES;
;;;;;;;;;;;;;;;;;;;;;;
P9:  mov    bp,prime
     mov    si,10d
     mov    di,0
moreprimes:
     cmp    di,50
     je     progfinish
     mov    ax,[bp]
     xor    dx,dx
     push   20h
     mov    cx,1d
nonzero:
     div    si
     add    dl,"0"
     push   dx
     inc    cx
     xor    dx,dx
     cmp    ax,0h
     jne    nonzero
writeloop:
     pop    dx
     mov    ah,02h
     int    21h
     dec    cx
     jnz    writeloop
     add    bp,2
     inc    di
     jmp    moreprimes
progfinish:
     int    20h
prime:
     dw    2
code ends

a) Fill in the empty boxes shown in the above assembly source. (Write your answer in the comments area). b) Look at the C-source again, and write down the corresponding operand (in PART 1 of assembly source) to the following variables:

• prime
• prime[k]
• prime[j]
• N
• quo
• rem
• j

Problem 7
The following program reads a line and prints it. a) Explain in DETAIL whether the following program has any bugs in it. b) If there are bug(s), rewrite the program without bugs. Note that you should keep the same functions. You are allowed to change parameters of functions.

#include <stdio.h>

char *readline()
{
   char line[80]  ; 

   printf("Enter a line:\n") ; 
   fgets(line,79,stdin) ; 
   return(line) ; 
}

void printline(char *line)
{
   printf("The line is:\n") ; 
   printf("%s",line) ; 
}

main()
{
   int i ; 
   char *line ; 

   for(i=0 ;  i < 1000000 ; i++) {
     line = readline() ; 
     printline(line) ; 
   }
}

Problem 8
Write a program that reads a text file containing lines of up to 60 characters and then prints it on the standard output in such a way that each line has no more than 40 characters. Note that you should pack as many tokens on a line as possible. You should also get the name of the text file from the command line. As an example, the following input:

She    sells sea shells by the seashore. The rain in 
Spain  remains in the plains. Debbie bought a little
bit of better butter. 

She sells sea shells by the seashore. 
The rain in Spain  remains in the
plains. Debbie bought a little bit of 
butter.

Problem 9
Write a program that reads a text file containing tokens separated by delimiters (blank,comma, semicolon, newline and period). The output of your program should be the list of tokens and their number of occurences in the file. As an example, for the following file:

If you can dream - and not make dreams your master;
If you can think - and not make thoughts your aim;
- Rudyard Kipling 

You should produce something like the following output: (order of words is not important)

IF  2
YOU 2
CAN 2
DREAM 1
-     3
AND   2
NOT   2
MAKE  2
DREAMS 1
YOUR  2
MASTER 1
THINK  1
THOUGHTS 1
AIM   1
RUDYARD 1
KIPLING 1

Problem 10
Write a C++ program which implements a generic sorting routine (Note: you can use any sorting algorithm you prefer, e.g. insert sort, bubblesort etc). You should use some features of C++ that are not available in C to implement your sorting routine. The following program shows how your routine is to be used. The mysort routine should accept array of data items, the number of data items and the comparison function which takes references to the two data items. Note that your implementation should conform to the usage as shown in the program below. If you do not conform (e.g if you change the number of parameters mysort routine etc), you will get 0.

#include <iostream.h>

/***** Your answer here *************
  Implement mysort routine as well as 
  any other routine you may need 
  (e.g. swap) HERE 
*************************************/

struct person {
   char name[15] ;
   int  age      ;
} ;

int person_compare(
person & p,
person & q)
{
   return(p.age - q.age) ; 
}

int int_compare(
int & p,
int & q)
{
  return(p - q)  ;
}

main()
{
   int   idata[9] = {1,5,3,6,2,7,8,1,1} ;
   struct person pdata[] = { 
            {"Veli",23},{"Ayse",24},{"Can",11},
            {"Mehmet",32},{"Ahmet",30},
            {"Pamela",20},  {"Cindy",29}} ;
   int   i ; 


   // sort the integer array 
   mysort(idata,9,int_compare) ; 
   for(i=0 ; i < 9 ; i++) {
     cout << idata[i] << endl ; 
   }

   // sort person array according to age 
   mysort(pdata,7,person_compare) ; 
   for(i=0 ; i < 7 ; i++) {
     cout << pdata[i].name 
          << "'s age is " 
          << pdata[i].age << endl ; 
   }

}