Function DecodeDouble

src/util/serfloat.cpp:10–35

#include <limits>

double DecodeDouble(uint64_t v) noexcept {
    static constexpr double NANVAL = std::numeric_limits<double>::quiet_NaN();
    static constexpr double INFVAL = std::numeric_limits<double>::infinity();
    double sign = 1.0;
    if (v & 0x8000000000000000) {
        sign = -1.0;
        v ^= 0x8000000000000000;
    }
    // Zero
    if (v == 0) return copysign(0.0, sign);
    // Infinity
    if (v == 0x7ff0000000000000) return copysign(INFVAL, sign);
    // Other numbers
    int exp = (v & 0x7FF0000000000000) >> 52;
    uint64_t man = v & 0xFFFFFFFFFFFFF;
    if (exp == 2047) {
        // NaN
        return NANVAL;
    } else if (exp == 0) {
        // Subnormal
        return copysign(ldexp((double)man, -1074), sign);
    } else {
        // Normal
        return copysign(ldexp((double)(man + 0x10000000000000), -1075 + exp), sign);
    }
}

uint64_t EncodeDouble(double f) noexcept {
    int cls = std::fpclassify(f);