Packing to and from different numerical types.

bitshifter.cs

// How do I get these two sets of methods to return the same output value?

void Main()
{
	uint x1 = PackUint(0.5f, 1, 0.5f, 1);
	byte[] b1 = ToBytes(x1);
	x1.Dump(); // 4286644096
	b1.Dump(); // 128, 255, 128, 255 RIGHT! :)

	ulong x2 = PackUlong(0.5f, 1, 0.5f, 1);
	byte[] b2 = ToBytes(x2);
	x2.Dump(); // 18446603340516130816
	b2.Dump(); // 255, 128, 0, 255 WRONG! :(
}

// Define other methods and classes here
public static ulong PackUlong(float r, float g, float b, float a)
{
	return ((ulong)Math.Round(r * 65535f) << 32) |
		   ((ulong)Math.Round(g * 65535f) << 16) |
		   (ulong)Math.Round(b * 65535f) |
		   ((ulong)Math.Round(a * 65535f) << 48);
}

private static uint PackUint(float r, float g, float b, float a)
{
	return ((uint)Math.Round(r * 255f) << 16) |
		   ((uint)Math.Round(g * 255f) << 8) |
		   (uint)Math.Round(b * 255f) |
		   ((uint)Math.Round(a * 255f) << 24);
}

public static byte[] ToBytes(ulong packed)
{
	return new[]
	{
		(byte)((packed >> 16) & 255),
		(byte)((packed >> 8) & 255),
		(byte)(packed & 255),
		(byte)((packed >> 24) & 255)
	};
}

public static byte[] ToBytes(uint packed)
{
	return new[]
	{
		(byte)((packed >> 16) & 255),
		(byte)((packed >> 8) & 255),
		(byte)(packed & 255),
		(byte)((packed >> 24) & 255)
	};
}

How do I get these two sets of methods to return the same output value?

The uint based methods work perfectly but the ulong ones fail.

I don't think you got your ToBytes(ulong packed) shift values updates. Should probably shift by 16, 32 and 48 bits. I haven't tested the modified code though.

Yeah I tried that originally actually. This gives me 0, 255, 0, 255 which is wrong.

Think I got it now:

    public static byte[] ToBytes(ulong packed)
    {
        return new[]
        {
            (byte)((packed >> 40) & 255),
            (byte)((packed >> 24) & 255),
            (byte)((packed >> 8) & 255),
            (byte)((packed >> 56) & 255)
        };
    }

Have to remember to use the most significant 8 bits.

I even tried out the code this time :-)

Perfect thanks!