Section: Floating point processing Taps (3stap)
Updated: November 2020
function::fp_to_long - Convert fp to int64
the 64 bit floating point stored in long
through 0-6, which are round to nearest even, minMag, min, max, near maxMag and round to odd
the boolean value, if exact is 1 than raising inexact exception, otherwise ignore the exception.
Given a 64 bit floating point, which is stored in long, use the long value to initiate self-defined float64_t type, then apply the f64_to_i64 function to get the string representation.