MSP430 IAR C/C++ Compiler reference guide - Rice University

Data representation64-bit floating-point formatThe representation of a 64-bit floating-point number as an integer is:63 62 52 51 0S Exponent MantissaThe exponent is 11 bits, and the mantissa is 52 bits.The value of the number is:(-1) S * 2 (Exponent-1023) * 1.MantissaThe range of the number is:±2.23E-308 to ±1.79E+308The precision of the float operators (+, -, *, and /) is approximately 15 decimal digits.Representation of special floating-point numbersThe following list describes the representation of special floating-point numbers:● Zero is represented by zero mantissa and exponent. The sign bit signifies positive ornegative zero.● Infinity is represented by setting the exponent to the highest value and the mantissato zero. The sign bit signifies positive or negative infinity.● Not a number (NaN) is represented by setting the exponent to the highest positivevalue and the mantissa to a non-zero value. The value of the sign bit is ignored.Note: The IAR CLIB Library does not fully support the special cases of floating-pointnumbers, such as infinity and NaN. A library function which gets one of these specialcases of floating-point numbers as an argument may behave unexpectedly.Pointer typesThe MSP430 IAR C/C++ Compiler has two basic types of pointers: function pointersand data pointers.FUNCTION POINTERSFor the MSP430 architecture, function pointers are always 16 bits. For the MSP430Xarchitecture, function pointers are 20 bits (4 bytes when stored in memory) and they canaddress the entire 1 Mbyte of memory.Part 2. Compiler reference173