A C function to compute an average without the risk of integer overflow

BitwiseMagic.c

#include <stdio.h>

/* https://twitter.com/mikeash/status/240471662422810624
 * Compute average with no possibility of integer overflow.
 * Note: patented in 1996, so you can't use it!
 */
int patentedAverage(int a, int b)
{
	int av = (a/2) + (b/2) + (a&b&1);
	return av;
}

/* http://aggregate.org/MAGIC/#Average%20of%20Integers */
int alternativeAverage(int a, int b)
{
	int av = (a&b)+((a^b)>>1);
	return av;
}

int main(int argc, char *argv[])
{
	int a = 10;
	int b = 20;
	
	int av = patentedAverage(a, b);
	printf("Patented average: %d\n", av);
	
	int alt = alternativeAverage(a, b);
	printf("Alternative average: %d\n", alt);
	
	return 0;
}

This is not parented, other people have discovered this code

This appears to be the patent. https://patents.google.com/patent/US5751617A/en

I just dropped it in a gist because I saw the tweet from mikeash and thought it was interesting.