// Similar to packHalf2x16, but the two values share exponent, and are stored
// as 12-bit fixed point numbers multiplied by that exponent (the leading one
// can't be implicit in this kind of format). This allows us to store a much
// Similar to packHalf2x16, but the two values share exponent, and are stored
// as 12-bit fixed point numbers multiplied by that exponent (the leading one
// can't be implicit in this kind of format). This allows us to store a much