1 files changed, 47 insertions, 0 deletions
diff --git a/circuitpython/shared-module/rainbowio/__init__.c b/circuitpython/shared-module/rainbowio/__init__.c
new file mode 100644
index 0000000..b1745c3
--- /dev/null
+++ b/circuitpython/shared-module/rainbowio/__init__.c
@@ -0,0 +1,47 @@
+/*
+ * 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.
+ */
+
+#include "shared-bindings/rainbowio/__init__.h"
+
+int32_t colorwheel(mp_float_t pos) {
+    pos = pos - ((uint32_t)(pos / 256) * 256);
+    int shift1, shift2;
+    if (pos < 85) {
+        shift1 = 8;
+        shift2 = 16;
+    } else if (pos < 170) {
+        pos -= 85;
+        shift1 = 0;
+        shift2 = 8;
+    } else {
+        pos -= 170;
+        shift1 = 16;
+        shift2 = 0;
+    }
+    int p = (int)(pos * 3);
+    p = (p < 256) ? p : 255;
+    return (p << shift1) | ((255 - p) << shift2);
+}