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| Developer(s) | Ben Brewer |
|---|---|
| Stable release | r64 / February 2, 2012; 12 years ago (2012-02-02) |
| Repository | |
| Written in | C99 |
| Operating system | Cross-platform |
| Type | fixed-point math library |
| License | MIT |
| Website | code |
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). 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.
History
libfixmath was developed by Ben Brewer and first released publicly as part of the Dingoo SDK. It has since been used to implement a software 3D graphics library called FGL.
Q16.16 functions
| 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 |
Other functions
| 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 |
Performance
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.
Licensing
libfixmath is released under the MIT License, a permissive free software licence, and is free software.
See also
References
- "libfixmath Project Page". GitHub.
- "64-bit Compiler Support Issues".
- "Dingoo SDK Project Page".
- "FGL Flatmush/Fixed-Point Graphics Library Project Page".
- "fixtest Download Page".