Explicit Conversions of ap_[u]fixpt

There are several functions to explicitly convert ap_[u]fixpt types into other types, besides value based assignments. The raw_bits function produces a uint of the same width as the ap_[u]fixpt with the same raw data, and to_double returns a double representing the value of the ap_[u]fixpt. Note that for wide enough ap_[u]fixpt to_double can lose precision, and can be inefficient in hardware. These are demonstrated in the following code snippet.

#include "hls/ap_fixpt.hpp"
#include <iostream>
#include <stdio.h>

using namespace hls;

    //...
    ap_fixpt<12, 5> ffixed("898");

    ap_uint<12> logical_fixed = ffixed.raw_bits();
    logical_fixed == 0x898; // true

    double double_fixed = ffixed.to_double();
    double_fixed == -14.8125; // true