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| author | William Chang <william@factual.com> | 2019-07-13 10:18:33 -0700 |
|---|---|---|
| committer | William Chang <william@factual.com> | 2019-07-13 10:18:33 -0700 |
| commit | 71493b2f9bbd5f3d18373c518fa14ccafcbf48fc (patch) | |
| tree | 3bb3e5e496621535611e087720aa5c4d7a533e5e /lib | |
| parent | 86ad4988fe7ff64916127509d84f44c56fa097aa (diff) | |
| parent | da1f05fbc19477c05c0c01bb07fabfaf1ece9d54 (diff) | |
| download | firmware-71493b2f9bbd5f3d18373c518fa14ccafcbf48fc.tar.gz firmware-71493b2f9bbd5f3d18373c518fa14ccafcbf48fc.tar.bz2 firmware-71493b2f9bbd5f3d18373c518fa14ccafcbf48fc.zip | |
Merge branch 'master' of https://github.com/qmk/qmk_firmware
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/lib8tion/trig8.h | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/lib/lib8tion/trig8.h b/lib/lib8tion/trig8.h index 6ef3ce625..cfba6373f 100644 --- a/lib/lib8tion/trig8.h +++ b/lib/lib8tion/trig8.h @@ -255,5 +255,30 @@ LIB8STATIC uint8_t cos8( uint8_t theta) return sin8( theta + 64); } +/// Fast 16-bit approximation of atan2(x). +/// @returns atan2, value between 0 and 255 +LIB8STATIC uint8_t atan2_8(int16_t dy, int16_t dx) +{ + if (dy == 0) + { + if (dx >= 0) + return 0; + else + return 128; + } + + int16_t abs_y = dy > 0 ? dy : -dy; + int8_t a; + + if (dx >= 0) + a = 32 - (32 * (dx - abs_y) / (dx + abs_y)); + else + a = 96 - (32 * (dx + abs_y) / (abs_y - dx)); + + if (dy < 0) + return -a; // negate if in quad III or IV + return a; +} + ///@} #endif |