package ro.pub.cs.pp.a51hadoop.algorithm.a51;

public class A51Bitops
{

	public static int reverse_bits_int(int x)
	{
		int nr_bits = 32;
		int ret = 0;
		for (int i = 0; i < nr_bits; i++)
			if ((x & 1 << i) != 0)
				ret |= 1 << (nr_bits - 1 - i);
		return ret;
	}

	public static long reverse_bits_long(long x)
	{
		int nr_bits = 64;
		long ret = 0;
		long one = 1;
		for (int i = 0; i < nr_bits; i++)
			if ((x & one << i) != 0)
				ret |= one << (nr_bits - 1 - i);
		return ret;
	}

	public static int parity(int x)
	{
		x ^= x >> 16;
		x ^= x >> 8;
		x ^= x >> 4;
		x ^= x >> 2;
		x ^= x >> 1;
		return x & 1;
	}


	/* Clock one shift register */
	public static int clockone(int reg, int mask, int taps)
	{
		int t = reg & taps;
		reg = (reg << 1) & mask;
		reg |= parity(t);
		return reg;
	}



	/*
	 * @return 1 or 0 as the i-th bit of x is 1 or 0
	 */
	public static int get_ith_bit(int x, int i)
	{
		return (x & (1 << i)) >> i;
	}

}