any logic to small the code ????

Question

//-----write a function of increment by bitwise opretor
//-----suggest me the simple logic for that

#include<stdio.h>
int plus(int,int);
int main()
{
int M,P,i,mask=1;
printf("enter the number\n");
scanf("%d",&i);
P=plus(i,mask);
printf(" number = %d , plus = %d\n",i,P);

return 0;
}
int plus(int num,int mask)
{
int j=0;
if((num&mask)==0)
return num=num|mask;
else
{
while((num&mask)!=0)
{ mask<<=1;
++j;
}
if((num&mask)==0)
num=num|mask;
num=num>>j;
num=num<<j;

return num;
}
}