Bitwise Operators are mainly used in low-level programming. Using the bit-wise operators we can set bit, check bit, clear or toggle the bits of an integral type. In the embedded system, a bit-wise operator performs the bit-wise operation on an individual bit of a PORT or Register.
Note: Quiz on bit-wise operators.
Note: Here I assume that bit of register starts with 0th position, it means the 2nd position is actually the 3rd bit.
| D7 | D6 | D5 | D4 | D3 | D2 | D1 | D0 |
Setting N-th Bit
Setting an N-th bit means that if the N-th bit is 0, then set it to 1 and if it is 1 then leave it unchanged. In C, bitwise OR operator (|) used to set a bit of integral data type. As we know that | (Bitwise OR operator) evaluates a new integral value in which each bit position is 1 only when operand’s (integer type) has a 1 in that position.
In simple words, you can say that “Bitwise OR ” of two bits is always one if any one of them is one.
That means, 0 | 0 = 0 1 | 0 = 1 0 | 1 = 1 1 | 1 = 1
Algorithm to set the bits:
Number | = (1UL << nth Position);
Method1: Set nth- bit in C using the function:
#include <stdio.h>
//function to set bit
int setBit(unsigned int data,unsigned int pos)
{
return (data|(1 << pos));
}
int main()
{
unsigned int cData=0x00;
unsigned int pos =0;
printf("cData = 0x%x\n\n",cData);
//Get position from the user
printf("Enter the position which you want set = ");
scanf("%u",&pos);
//Call function to set the bit
cData = setBit(cData,pos);
//Print the data
printf("\n\n%dth Bit Set Now cData will be = 0x%x\n",pos,cData);
return 0;
}
OutPut:
Explanation:
0 is represented as 0 in binary and has its D2 bit(third bit) 0, so setting it will result in 100 i.e. 4.
Method2: Set nth- bit in C using macro
#include <stdio.h>
//Macro to set nth-bit
#define SET_BIT(value, pos) (value |= (1U<< pos))
int main()
{
//value
unsigned int value =0;
//bit position
unsigned int pos = 0;
printf("Enter the value = ");
scanf("%u",&value);
printf("Enter the position you want to Set = ");
scanf("%u",&pos);
//Calling Macro to set nth-bit
printf("After setting nth-bit value will be = %d\n",SET_BIT(value,pos));
return 0;
}
OutPut:
Enter the value = 5
Enter the position you want to Set = 0
After setting nth-bit value will be = 5
Explanation:
5 is represented as 101 in binary and has its first bit 1. So after setting the 0th position, it will result in 101 i.e. 5.
Clearing a Bit
Clearing a bit means that if N-th bit is 1, then clear it to 0 and if it is 0 then leave it unchanged. Bitwise AND operator (&) use to clear a bit of integral data type. “AND” of two bits is always zero if any one of them is zero.
That means, 0 & 0 = 0 1 & 0 = 0 0 & 1 = 0 1 & 1 = 1
Algorithm to clear the bit:
To clear the nth bit, first, you need to invert the string of bits then AND it with the number.
Number &= ~(1UL << nth Position);
Method1: Clear nth- bit in C using the function:
#include <stdio.h>
//function to clear nth-bit
int clearNthBit(unsigned int data,unsigned int pos)
{
return (data & (~(1 << pos)));
}
int main()
{
unsigned int cData=0xFF;
unsigned int pos =0;
printf("Initially cData = 0x%x\n\n",cData);
printf("Enter the position which you want clear = ");
scanf("%u",&pos);
//clear the nth bit.
cData = clearNthBit(cData,pos);
//Print the data
printf("\n\n%uth Bit clear Now cData will be = 0x%x\n",pos,cData);
return 0;
}
OutPut:
Explanation:
Clearing of D1 bit of 0XFF will give 0XFD.
Method2: Clear nth- bit in C using the macro:
#include <stdio.h>
//Macro to clear nth-bit
#define CLEAR_BIT(value, pos) (value &= (~(1U<< pos)))
int main()
{
unsigned int cData=0xFF;
unsigned int pos =0;
printf("Initially cData = 0x%x\n\n",cData);
printf("Enter the position which you want clear = ");
scanf("%u",&pos);
//Calling macro to clear nth-bit
printf("After clearing nth-bit cData will be = 0x%x\n",CLEAR_BIT(cData,pos));
return 0;
}
Output:
Initially cData = 0xff
Enter the position which you want clear = 0
After clearing nth-bit cData will be = 0xfe
Checking a Bit
To check the nth bit, shift the ‘1’ nth position toward the left and then “AND” it with the number.
An algorithm to check the bit
Bit = Number & (1UL << nth)
Method1: Check nth- bit in C using the function
#include <stdio.h>
#define SET 1
#define NOT_SET 0
//function to check nth bit
int isNthBitSet(unsigned int data,unsigned int pos)
{
return ((data & (1 << pos))? SET : NOT_SET);
}
int main()
{
//Given data
unsigned int cData=0xFc;
unsigned int pos =0;
unsigned int isBitSet = 0;
printf("Initially cData = 0x%x\n\n",cData);
printf("Enter the position which you want check = ");
scanf("%u",&pos);
//Check bit set or not
isBitSet = isNthBitSet(cData,pos);
if(isBitSet)
{
printf("\nBit is One\n");
}
else
{
printf("\nBit is zero\n");
}
return 0;
}
OutPut 1:
OutPut 2:
Method2: Check nth- bit in C using macro
#include <stdio.h>
//Macro to check nth-bit
#define IS_BIT_SET(value, pos) (value & (1U<< pos))
int main()
{
//Given data
unsigned int cData=0xFc;
unsigned int pos =0;
printf("Initially cData = 0x%x\n\n",cData);
printf("Enter the position which you want check = ");
scanf("%u",&pos);
//Macro to check nth bit
if(IS_BIT_SET(cData,pos))
{
printf("\n\nBit is One");
}
else
{
printf("\n\nBit is zero");
}
return 0;
}
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Toggling a Bit
Toggling a bit means that if the N-th bit is 1, then change it to 0 and if it is 0 then change it to 1. Bitwise XOR (^) operator used to toggle the bit of an integral data type. To toggle the nth bit shift the ‘1’ nth position toward the left and “XOR” it.
That means, 0 ^ 0 = 0 1 ^ 0 = 1 0 ^ 1 = 1 1 ^ 1 = 0
An algorithm to toggle the bits
Number ^= (1UL << nth Position);
A simple program to toggle a bit
#include <stdio.h>
#include <stdlib.h>
int main()
{
unsigned int cData=0xF8;
int pos =0;
system("COLOR F");
printf("Initially cData = 0x%x\n\n",cData);
printf("Enter the position which you want toggle = ");
scanf("%u",&pos);
//toggle the nth bit.
cData^=1<<pos;
//Print the data
printf("\n\n%uth Bit Set Now cData will be = 0x%x\n",pos,cData);
return 0;
}
Output:
OutPut 2:
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Your opinion matters
Although here I have tried to puts a lot of points regarding the bit operators but I want to know your opinion on the binary operators, so please don’t forget to write a comment in the comment box.