Function ToBinary

Dependencies/assimp/code/Common/SpatialSort.cpp:188–234

-------------------------------------------------------------------------------------------- Converts the bit pattern of a floating-point number to its signed integer representation.

// --------------------------------------------------------------------------------------------
// Converts the bit pattern of a floating-point number to its signed integer representation.
BinFloat ToBinary(const ai_real &pValue) {

    // If this assertion fails, signed int is not big enough to store a float on your platform.
    //  Please correct the declaration of BinFloat a few lines above - but do it in a portable,
    //  #ifdef'd manner!
    static_assert(sizeof(BinFloat) >= sizeof(ai_real), "sizeof(BinFloat) >= sizeof(ai_real)");

#if defined(_MSC_VER)
    // If this assertion fails, Visual C++ has finally moved to ILP64. This means that this
    //  code has just become legacy code! Find out the current value of _MSC_VER and modify
    //  the #if above so it evaluates false on the current and all upcoming VC versions (or
    //  on the current platform, if LP64 or LLP64 are still used on other platforms).
    static_assert(sizeof(BinFloat) == sizeof(ai_real), "sizeof(BinFloat) == sizeof(ai_real)");

    // This works best on Visual C++, but other compilers have their problems with it.
    const BinFloat binValue = reinterpret_cast<BinFloat const &>(pValue);
    //::memcpy(&binValue, &pValue, sizeof(pValue));
    //return binValue;
#else
    // On many compilers, reinterpreting a float address as an integer causes aliasing
    // problems. This is an ugly but more or less safe way of doing it.
    union {
        ai_real asFloat;
        BinFloat asBin;
    } conversion;
    conversion.asBin = 0; // zero empty space in case sizeof(BinFloat) > sizeof(float)
    conversion.asFloat = pValue;
    const BinFloat binValue = conversion.asBin;
#endif

    // floating-point numbers are of sign-magnitude format, so find out what signed number
    //  representation we must convert negative values to.
    // See http://en.wikipedia.org/wiki/Signed_number_representations.
    const BinFloat mask = BinFloat(1) << (CHAR_BIT * sizeof(BinFloat) - 1);

    // Two's complement?
    const bool DefaultValue = ((-42 == (~42 + 1)) && (binValue & mask));
    const bool OneComplement = ((-42 == ~42) && (binValue & mask));

    if (DefaultValue)
        return mask - binValue;
    // One's complement?
    else if (OneComplement)
        return BinFloat(-0) - binValue;
    // Sign-magnitude? -0 = 1000... binary
    return binValue;
}

} // namespace