fp is an ISO/IEC 9899:1999 (C99) compliant software floating point library. It supports up to 14 decimal digits of precision, utilizing an internal format based on packed BCD. I chose this format to mimic the floating point representation used on the TI-8x line of calculators. This format takes up slightly more (2 bytes) space than an IEEE 754 binary64 type, but it has several advantages:

• It's easy to read. Since the data is in BCD, you can examine and manipulate the hexadecimal representation easily.
• It accurately stores common values such as 0.1. This is not possible in base-2 floating point representations.

• tools/fpp: Preprocessor used to turn %FP(...) or %FP_CONST(...) into an internal representation.
• tools/fp-calc: Simple REPL used to provide interactive testing of library.

• Basic arithmetic (+, -, *, /) and comparison
• Polynomial evaluation using the Horner scheme
• Conversion operations to/from various data types
• Arithmetic-geometric mean
• Exponential functions (exp, pow, log, sqrt) (WIP)

• Basic trigonometric functions (sin, cos, tan)

The only programs required to build this program are gcc, bison and flex. To build and install, all you have to do is

$ make && sudo make install

The API is designed for ease of use over efficiency. You can find examples available in the ex directory. If %FP(...) or %FP_CONST(...) is used in your source code for floating-point constants, you need to run your code through the fpp preprocessor before compiling. A sample invocation is given below:

$ fpp mycode.c | gcc -xc - -o mycode