libfixmath

Cross Platform Fixed Point Maths Library

PetteriAimonen
759
174
C

libfixmath

This is a mirror of the libfixmath’s original SVN repository on Google Code.

Not actively maintained, pull requests welcome.

Libfixmath implements Q16.16 format fixed point operations in C.

License: MIT

Options

Configuration options are compile definitions that are checked by the preprocessor with #ifdef and #ifndef. All of these are undefined by default.

FIXMATH_FAST_SIN

  • #ifndef: Most accurate version, accurate to ~2.1%.
  • #ifdef: Fast implementation, runs at 159% the speed of above ‘accurate’ version with a slightly lower accuracy of ~2.3%.

FIXMATH_NO_64BIT

  • #ifndef: For compilers/platforms that have uint64_t.
  • #ifdef: For compilers/platforms that do not have uint64_t.

FIXMATH_NO_CACHE

  • #ifndef: Use static memory caches for exponents (32KB) and trigonometry (80KB).
  • #ifdef: Do not use caches.

FIXMATH_NO_HARD_DIVISION

Note: will be automatically defined if FIXMATH_OPTIMIZE_8BIT is defined.

  • #ifndef: For platforms that have hardware integer division.
  • #ifdef: For platforms that do not have hardware integer division.

FIXMATH_NO_OVERFLOW

  • #ifndef: Check for overflow and return the overflow constants.
  • #ifdef: Do not check for overflow.

FIXMATH_NO_ROUNDING

  • #ifndef: Use rounding.
  • #ifdef: Do not use rounding.

FIXMATH_OPTIMIZE_8BIT

  • #ifndef: Do not optimize for processors with 8-bit multiplication like Atmel AVR.
  • #ifdef: Optimize for processors like Atmel AVR. Also defines FIXMATH_NO_HARD_DIVISION automatically in fix16.h.

Include the libfixmath library in your CMake Project

The simplest way to use libfixmath as a dependency is with CMake’s FetchContent API.

include(FetchContent)
FetchContent_Declare(
    libfixmath
    GIT_REPOSITORY https://github.com/PetteriAimonen/libfixmath.git
    GIT_TAG <the long git hash of the version you want>
)
FetchContent_MakeAvailable(libfixmath)

target_compile_definitions(libfixmath PRIVATE
    # FIXMATH_FAST_SIN
    # FIXMATH_NO_64BIT
    # FIXMATH_NO_CACHE
    # FIXMATH_NO_HARD_DIVISION
    # FIXMATH_NO_OVERFLOW
    # FIXMATH_NO_ROUNDING
    # FIXMATH_OPTIMIZE_8BIT
)

target_link_libraries(my_cmake_project PRIVATE libfixmath)