I am considering using a C++ compiler instead of the Arduino IDE because it alows using 64 bit double floats and 64 bit long long int. So I am thinking if I take a 64bit float, multiply it by 10000.0 to shift the decimal, then cast it to a 64 bit signed int, it should trunicate at the point of precision my application requires.
From there I am still trying to figure out what to do. I need the int to fit into a 38bit signed 2's complement type. Assuming the measurement should fit into the capability of 37 bits and a sign bit can I just pull the bytes from an array. Read the sign bit from the original 64 bit number and map it onto the 38th bit of the number I need to send? If it does fit into the 37 bit value segment then all other bits would be 0 anyway, right?
I need the 38 bit int to represent a measurement to .0001 meters. The device send this in a 64bit float value.
I really need some guidence here.