Question

I need to be able to convert from a Delphi Real48 to C# double.

I’ve got the bytes I need to convert but am looking for an elegant solution. to the problem.

Anybody out there had to do this before?

I’m needing to do the conversion in C#

Thanks in advance

Answer 1

I’ve done some hunting around and I found some C++ code to do the job, converted it and it seems to be giving the right answer… damned if I understand it all though :S

    private static double Real48ToDouble(byte[] real48)
    {

        if (real48[0] == 0)
            return 0.0; // Null exponent = 0

        double exponent = real48[0] - 129.0;
        double mantissa = 0.0;

        for (int i = 1; i < 5; i++) // loop through bytes 1-4
        {
            mantissa += real48[i];
            mantissa *= 0.00390625; // mantissa /= 256
        }


        mantissa += (real48[5] & 0x7F);
        mantissa *= 0.0078125; // mantissa /= 128
        mantissa += 1.0;

        if ((real48[5] & 0x80) == 0x80) // Sign bit check
            mantissa = -mantissa;

        return mantissa * Math.Pow(2.0, exponent);
    }

If somebody can explain it that would be great 😀