title: How to define custom float-point format (type) in C++?
body: <p>How can I define my own float-point format (type) with specific precision and certain bitness of exponent and significand? For example, 128-bit float-point number with 20-bit exponent and 107-bit significand (not standart 15/112-bit), or 256-bit one with 19/236-bit exponent/significand. </p>