Question

S4.1) Write C code to set all odd bits (b1, 63, b5, b7) in the uint_8 variable PORT. All other bits should not be changed. S4.2) Write C code to clear bits b3, 64, and b5 in the uint_8 variable PORT. All other bits should not be changed. S4.3) Write C code to toggle all even bits in the uint_8 variable PORT. All other bits should not be changed.

Answer 1

1. To set the bit we use bitwise OR operator because 0 | 0 = 1 and 1 | 0 = 1. So for setting a specific bit we use shift operator.

2. To set the bit we use bitwise OR operator because 0 & 0 = 0 and 1 & 0 = 0. So for clearing a specific bit we use shift operator.

3. To toggle the bit we use bitwise XOR operator because 0 ^ 1 = 1 and 1 ^ 1 = 0. So for toggling a specific bit we use shift operator.

Code:

//you can use int instead of unit8_t.

#include<stdio.h>

#include<stdint.h>

//function to set odd bits.

uint8_t set(uint8_t n){   

    for(uint8_t i=1;i<=8;i+=2){

        n = (n | (1 << (i - 1)));

    }

    return n;

}

//function to clear b3,b4,b5 bits.

uint8_t clear(uint8_t n){

    for(uint8_t i=3;i<=5;i++){

        n = (n & (~(1 << (i - 1))));

    }

    return n;

}

//function to toggle even bits.

uint8_t toggle(uint8_t n){

    for(uint8_t i=2;i<=8;i+=2){

        n = (n ^ (1 << (i - 1)));

    }

    return n;

}

int main()

{

    uint8_t n = 6;

    printf("%d with odd bist Set: %d\n", n, set(n));

    printf("%d with bits b3,b4,b5 clear: %d\n", n, clear(n));

    printf("%d with even bits toggle: %d\n", n, toggle(n));

    return 0;

}

Screenshot of code:

1 #include<stdio.h> #include<stdint.h> 2 3 4 5 // function to set odd bits. uint8_t set(uint8_t n){ for(uint8_t i=1;i<=8;i+=2) { n = (n | (1 « (i - 1))); 8 9 10 return n; } //function to clear b3, 64, b5 bits. uint8_t clear(uint8_t n){ 11 12 13 14 for(uint8_t i=3;i<=5;i++){ n = (n & (~(1 « (i - 1)))); 15 16 17 18 return n; } 1/function to toggle even bits. uint8_t toggle(uint8_t n) 19 20 21 for(uint8_t i=2;i<=8;i+=2) { n = (n ^ (1 « (i - 1))); 22 23 24 25 26 27 return n; } 28 29 30 31 int main() { uint8_t n = 6; 32 33 printf("%d with odd bist Set: %d\n", n, set(n)); printf("%d with bits b3, b4,b5 clear: %d\n", n, clear(n)); printf("%d with even bits toggle: %d\n", n, toggle(n)); return 0; 34 35 36 }

Output :

6 with odd bits Set: 87 6 with bits b3, 64, b5 clear: 2 6 with even bits toggle: 172