32 bit Ripple Carry Adder in C

adder.c

/*
 * adder.c
 *
 *  Created on: Mar 8, 2014
 *      Author: braxton
 */
#include <stdio.h>

/*
 * Gets bit i of a.
 *
 * Returns 0 or 1, whichever the bit i is.
 */
int getBit(int a, int i)
{
	return ((a & (1 << i)) >> i);
}

/*
 * Adds bits a and b, taking into account the carry.
 */
int sum(carry_in, a, b)
{
	return ((carry_in ^ a) ^ b);
}

/*
 * Figures out what the carry-over is.
 */
int carry(carry_in, a, b)
{
	return (carry_in & a) & b;
}

/*
 * Sets bit i of result to be s, either 0 or 1.
 */
int setBit(result, i, s)
{
	if (s == 1)
		return result | (1 << i);
	return result & ~(1 << i);
}

int main()
{
	unsigned int x, y;
	scanf("%d %d", &x, &y);

	unsigned int result = 0;
	unsigned int carry_in = 0;

	unsigned int i = 0;
	unsigned int a = 0;
	unsigned int b = 0;
	for (i = 0; i < 32; i++) // probably can't use the increment op
	{
		a = getBit(x, i);
		b = getBit(y, i);

		unsigned int s = sum(carry_in, a, b);

		unsigned int carry_out = carry(carry_in, a, b);

		result = setBit(result, i, s);

		carry_in = carry_out;
	}

	if (carry_in > 0)
		printf("\n overflow has occurred, result incorrect\n");

	printf("%#x %d\n", result, result);

	return 0;
}

Just casually came across this, carry logic should be '(carry_in & (a ^ b)) | (a & b)' and scanf should use '%u' (for unsigned ints) instead of '%d' (for signed ints).