circuitpython/shared-module/rainbowio/__init__.c

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/*
* This file is part of the CircuitPython project, https://github.com/adafruit/circuitpython
*
* The MIT License (MIT)
*
* Copyright (c) 2021 Kattni Rembor
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
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#include "shared-bindings/rainbowio/__init__.h"
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int32_t colorwheel(mp_float_t pos) {
pos = pos - ((uint32_t)(pos / 256) * 256);
int shift1, shift2;
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if (pos < 85) {
shift1 = 8;
shift2 = 16;
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} else if (pos < 170) {
pos -= 85;
shift1 = 0;
shift2 = 8;
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} else {
pos -= 170;
shift1 = 16;
shift2 = 0;
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}
int p = (int)(pos * 3);
return (p << shift1) | ((255 - p) << shift2);
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}