德爾福軟體試題ZZ

德爾福軟體試題ZZ
shury 發表於 2004-12-6 14:27:00

1. How do you code an infinite loop in C?
2. Volatile:
   a) What does the keyword volatile mean? Give an example
   b) Can a parameter be both const and volatile? Give an example
   c) Can a pointer be volatile? Give an example
3.  What are the values of a, b, and c after the following instructions:
    int a=5, b=7, c;
    c = a+++b;
4,  What do the following declarations mean?
        a) const int a;
        b) int const a;
        c) const int *a;
        d) int * const a;
        e) int const * a const;
5.  Which of the following statements describe the use of the keyword
static?
a) Within the body of a function: A static variable maintains its value
      between function revocations

  b) Within a module: A static variable is accessible by all functions
      within that module
  c) Within a module: A static function can only be called by other
            functions within that module
6.  Embedded systems always require the user to manipulate bits in
registers or variables. Given an integer variable a, write two code fragments.
The first should set bit 5 of a. The second shnuld clear bit 5 of a. In both
cases, the remaining bits should be unmodified.
7.  What does the following function return?
      char foo(void)
      {
                 unsigned int a = 6;
                 iht b = -20;
                 char c;
                 (a+b > 6) ? (c=1): (c=0);
                 return c;
      }
8.  What values are printed when the following C program is executed?
      int i = 8;
      void main(void)
      (

 

9.  What will be the output of the following C code?
     main()
     {
            int k, num= 30;
            k =(num > 5 ? (num <=10 ? 100:200): 500);
            printf("%d", k);
     }
10. What will the following C code do?
        int *ptr;
        ptr =(int *)Ox67a9;
        *ptr = Oxaa55;
11. What will be the output of the follow C code?
     #define product(x) (x*x)
     main()
     {
         int i = 3, j, k;
         j = product(i++);
         k = product(++i);
         printf("%d %d",j,k);
     }
12. Simplify the following Boolean expression
      !((i ==12) || (j > 15))

13. How many flip-flop circuits are needed to divide by 16?
14. Provides 3 properties that make an OS, a RTOS?
15. What is pre-emption?
16. Assume the BC register value is 8538H, and the DE register
value is 62A5H.Find the value of register BC after the following
assembly operations:
        MOV A,C
        SUB E
        MOV C,A
        MOV A,B
        SBB D
        MOV B,A
17.In the Assembly code shown below
  LOOP: MVI C,78H
        DCR C
        JNZ LOOP
        HLT
How many times is the DCR C Operation executed?
18.Describe the most efficient way(in term of execution time
and code size) to divide a number by 4 in assembly language
19.what value is stored in m in the following assembly language code
fragment if n=7?

        LDAA #n
LABEL1: CMPA #5
        BHI  L3
        BEQ  L2
        DECA
        BRA  L1
LABEL2: CLRA
LABEL3: STAA #m
20. What is the state of a process if a resource is not
available?
21. Using the #define statement, how would you
declare a manifest constant that returns the
number of seconds in a year? Disregard leap
years in your answer.
22. Interrupts are an important part of embedded
systems. Consequently, many compiler vendors
offer an extension to standard C to support interrupts.
Typically, the keyword is __interrupt. The following
code uses __interrupt to define an interrupt service
routine (ISR). Point out problems in the code.

__interrupt double compute_area (double radius)

          double area = PI * radius * radius;
          printf("/nArea = %f", area);
          return area;
}