diff options
| author | Joel Bodenmann <joel@unormal.org> | 2013-11-10 21:07:16 +0100 |
|---|---|---|
| committer | Joel Bodenmann <joel@unormal.org> | 2013-11-10 21:07:16 +0100 |
| commit | da2740b706d720292113445ee1db30f8a9873dc4 (patch) | |
| tree | 8f8b1902d4af6a23b3daf26990f580b76ea31ea4 /include/gmisc/gmisc.h | |
| parent | 6ca3537a696e7ace8098771a9a7105380604253d (diff) | |
| parent | a8ce005e2621b0108863297948cea0fa52c8bf2a (diff) | |
| download | uGFX-da2740b706d720292113445ee1db30f8a9873dc4.tar.gz uGFX-da2740b706d720292113445ee1db30f8a9873dc4.tar.bz2 uGFX-da2740b706d720292113445ee1db30f8a9873dc4.zip | |
merging GDISPStreaming
Diffstat (limited to 'include/gmisc/gmisc.h')
| -rw-r--r-- | include/gmisc/gmisc.h | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/include/gmisc/gmisc.h b/include/gmisc/gmisc.h index 998dda50..ff3d0c76 100644 --- a/include/gmisc/gmisc.h +++ b/include/gmisc/gmisc.h @@ -51,6 +51,7 @@ typedef int32_t fixed; */ #define FIXED(x) ((fixed)(x)<<16) /* @< integer to fixed */ #define NONFIXED(x) ((x)>>16) /* @< fixed to integer */ +#define FIXED0_5 32768 /* @< 0.5 as a fixed (used for rounding) */ #define FP2FIXED(x) ((fixed)((x)*65536.0)) /* @< floating point to fixed */ #define FIXED2FP(x) ((double)(x)/65536.0) /* @< fixed to floating point */ /* @} */ @@ -183,6 +184,23 @@ extern "C" { /** @} */ #endif +#if GMISC_NEED_INVSQRT + /** + * @brief Fast inverse square root function (x^-1/2) + * @return The approximate inverse square root + * + * @param[in] n The number to find the inverse square root of + * + * @note This function generates an approximate result. Higher accuracy (at the expense + * of speed) can be obtained by modifying the source code (the necessary line + * is already there - just commented out). + * @note This function relies on the internal machine format of a float and a long. + * If your machine architecture is very unusual this function may not work. + * + * @api + */ + float invsqrt(float n); +#endif #ifdef __cplusplus } #endif |