Missing Max Function?

Hi,

An example of something I often have to do - I have a vector with (say) 1024 floating point values and I want the maximum of every 8 values, i.e.

output[0] = max (input, 0 to 7)
output[1] = max (input, 8 to 15)
output[2] = max (input, 15 to 23)
etc.

So what's the correct / most efficient way to do this? I don't think there's a function...