Question

PLEASE ANSWER I WILL RATE YOUR ANSWER AND THUMBS UP

For the following C functions:

int q7(int x) {

    return x & (~x+1);

}

int q8(int x, int m, int n) {

    int a = ~m+1;

    int b = ~x +1;

    a = x + a;

    b = b + n;

    return !((a|b) >> 31);

}

int q9(int x, int n) {

   /* assume x and n are not a negative integer */

    int temp = (1 << n);

    int z = temp + ~0;

    return (z & x);

}

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Part i) Explain what each function does without running the code. EXPLAIN YOUR ANSWER OR YOU WILL NOT RECEIVE CREDIT.

Part ii) For each of the above functions, write a simpler version of the function (if there is one)

Answer 1

Let us analyze each of the fuction,

Given function,

A)

int q7(int x) {

    return x & (~x+1);

}

i) Explaination: Given function computes bitwise and with its compliment plus one, and therefore returns 1 if least significiant bit 1, else return 2 for least significiant bit 0.

ii) above function already in simpler form.

B)

int q8(int x, int m, int n) {

    int a = ~m+1;

    int b = ~x +1;

    a = x + a;

    b = b + n;

    return !((a|b) >> 31);

}

i) Explaination: given function q8 takes 3 input parameter and computes bitwise compliment for first and second integer bit + 1, and add integer first integer with computed second bitwise integer store as int a, and second with third integer store as b, returns compliment of bitwise a or b shifting 31 bits to right. in simpler words we simply divide a | b with 2, 31 times, so function already in simpler form.

C)

int q9(int x, int n) {

   /* assume x and n are not a negative integer */

    int temp = (1 << n);

    int z = temp + ~0;

    return (z & x);

}

i) Explaination: function q9 takes two integer, shift bitwise left which means multiplying with 2 second integer n and store in temp, integer z stores temp subtracted with one, since bitwise compliment of 0 returns -1, finally return bitwise and of z and first integer x parameter.

In simpler words always integer second parameter or n value will be returned.

ii) More simplified version:

int q9(int x, int n) {
        /* assume x and n are not a negative integer */
        return n;

}