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libfixmath is a platform-independent fixed-point math library aimed at developers wanting to perform fast non-integer math on platforms lacking a (or with a low performance) FPU. It offers developers a similar interface to the standard math.h functions for use on Q16.16 fixed-point numbers. libfixmath has no external dependencies other than stdint.h and a compiler which supports 64-bit integer arithmetic (such as GCC).cite-ref-1[1] Conditional compilation options exist to remove the requirement for a 64-bit capable compiler as many compilers for microcontrollers and DSPs do not support 64-bit arithmetic.cite-ref-2[2]

• History

• Q16.16 functions

• Other functions

• Performance

• Licensing

• See also

• References

• External links

libfixmath was developed by Ben Brewer and first released publicly as part of the Dingoo SDK.cite-ref-3[3] It has since been used to implement a software 3D graphics library called FGL.cite-ref-4[4]

| Name | Description |

|---|---|

| fix16_acos | inverse cosine |

| fix16_asin | inverse sine |

| fix16_atan | one-parameter inverse tangent |

| fix16_atan2 | two-parameter inverse tangent |

| fix16_cos | cosine |

| fix16_exp | exponential function |

| fix16_sin | sine |

| fix16_sqrt | square root |

| fix16_tan | tangent |

| fix16_mul | multiplication |

| fix16_div | division |

| fix16_sadd | saturated addition |

| fix16_smul | saturated multiplication |

| fix16_sdiv | saturated division |

| Name | Description |

|---|---|

| fix16_to_dbl | Convert Q16.16 to a double |

| fix16_to_float | Convert Q16.16 to a float |

| fix16_to_int | Convert Q16.16 to an integer |

| fix16_from_dbl | Convert double to a Q16.16 |

| fix16_from_float | Convert float to a Q16.16 |

| fix16_from_int | Convert integer to a Q16.16 |

For the most intensive function (atan2) benchmark results show the following results:

| Name | Time Compared to Float |

|---|---|

| ARM Cortex-M0 | 26.3% |

| Marvell PXA270 ( ARM ) @ 312 MHz | 58.45% |

| Intel T5500 | 120% |

| Intel Atom N280 | 141% |

Note: These results were calculated using fixtest with caching optimizations turned off.cite-ref-5[5]

libfixmath is released under the MIT License, a permissive free software licence, and is free software.

• Binary scaling

• Fixed-point arithmetic

• Floating-point arithmetic

• Q (number format)

cite-note-11. ↑ "libfixmath Project Page". GitHub.

cite-note-22. ↑ "64-bit Compiler Support Issues".

cite-note-33. ↑ "Dingoo SDK Project Page".

cite-note-44. ↑ "FGL Flatmush/Fixed-Point Graphics Library Project Page".

cite-note-55. ↑ "fixtest Download Page".

• Project Page

• Group Page/Mailing List