Bit Manipulation

Get Bit from the particular Position Suppose you want to get a bit from the 4 th position. You can call int get_bit_val(int number_send,int position) function. In this function, number_send is our data from where we want to get a bit. Second pass the position from where you want to get a bit.

Get Bit function int get_bit_val(int number_send,int position) { int number1=1; number1=number1<<(position-1); if(number_send & number1) { return (1); } else { return (0); }

How Get bit function works? First argument we can pass as int. so ascii value is passed there as a number_send. Suppose user has entered a character N that you pass as a argument to get bit function. Ascii of N is 78 that is Second argument you pass for the 4 th position bit.

Contd. In the first step number1 =1 is initialized. Number_send Number1 Number1<<(position-1) : Number1<<3 Number_send Number

if((number_send & number1)) return (1); else return (0); Number_send Number1 It will generate answer 0 or 1 as per the number_send value. In this case, it will generate 1. Contd &

Set Bit function Through this function, we can set the bit with our own value on the particular position. The function void setbit(int *data, int pos, int val) takes 3 argument one is data, second is position and third is the value which we want to set on the particular position in the data.

Set Bit Function void setbit(int *data, int pos, int val) { int mask=1; mask = mask<<(pos-1); if(val==0) { mask=~mask; *data=*data & mask; } else { *data=*data | mask; }

How set bit function works? First one variable mask is initialized with one then after it is shifted on the particular position. Then if value which is passed as third argument, if it is 0 then mask is complemented. So, if we perform data & mask then it sets 0 on that position. If value which we want to set is 1 then data is ored with 1 so it sets 1 on that position.

Example In the set bit function suppose arguments are for data N, position is 4 and new value what we want to set is 0. Initially it is Data Mask After performing left shift for mask Data Mask

if(val==0) { mask=~mask; *data=*data & mask; } In our case value is 0, means we want to set 0 on 4 th position. mask ~mask Then last operation is data & mask Example & =

Insert Bit int ins_bit_pos(int number_send,int position,int value) { int num1,num2; num1=number_send; num1=num1>>(position-1); num1=num1<<(position-1); num2=number_send-num1; num1=num1<<1; num1=num1 | num2; if(value==1) { num1=set_bit_val(num1,position,value); } return (num1); }

We want to add bit 0 on the 3rd position. Suppose number_send is N. which is assigned to num1 in the first step. So, Num1 Num1>> (position-1) Num1<<(position-1) Num2 = number_send – num =

num1= num1<<1 num1= Num1<<1 num1 = num1|num2 Bit 0 is set on the 3 rd Position | =