浮点运算软实现

http://www.jhauser.us/arithmetic/SoftFloat.html

mpfr
 The MPFR library is a C library for multiple-precision floating-point
computations with correct rounding.
GCC 就是用的 mpfr

http://gcc.gnu.org/onlinedocs/gccint/Soft-float-library-routines.html

mathFP (for java)