Ex_2.6_setbits.c

/**
 *
 * Exercise 2.6 -  Write a function setbits(x,p,n,y) that returns x with the
 * n bits that begin at positionp set to the rightmost n bits of y,leaving
 * the other bits unchanged.
 **/

#include<stdio.h>

unsigned setbits(unsigned x,int p,int n,unsigned y);

int main(void)
{
	printf("%u",setbits((unsigned)12,3,2,(unsigned)57));
}

unsigned setbits(unsigned x,int p,int n,unsigned y)
{
	return x & ~(~(~0 << n) << (p+1-n)) | ( y & (~(~0<<n)) << (p+1-n));
}