1 files changed, 85 insertions, 0 deletions
diff --git a/lcd_backlight.c b/lcd_backlight.c
new file mode 100644
index 0000000000..70187d1e00
--- /dev/null
+++ b/lcd_backlight.c
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+/*
+The MIT License (MIT)
+
+Copyright (c) 2016 Fred Sundvik
+
+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 "lcd_backlight.h"
+#include <math.h>
+
+static uint8_t current_hue = 0x00;
+static uint8_t current_saturation = 0x00;
+static uint8_t current_intensity = 0xFF;
+static uint8_t current_brightness = 0x7F;
+
+void lcd_backlight_init(void) {
+    lcd_backlight_hal_init();
+    lcd_backlight_color(current_hue, current_saturation, current_intensity);
+}
+
+// This code is based on Brian Neltner's blogpost and example code
+// "Why every LED light should be using HSI colorspace".
+// http://blog.saikoled.com/post/43693602826/why-every-led-light-should-be-using-hsi
+static void hsi_to_rgb(float h, float s, float i, uint16_t* r_out, uint16_t* g_out, uint16_t* b_out) {
+    unsigned int r, g, b;
+    h = fmodf(h, 360.0f); // cycle h around to 0-360 degrees
+    h = 3.14159f * h / 180.0f; // Convert to radians.
+    s = s > 0.0f ? (s < 1.0f ? s : 1.0f) : 0.0f; // clamp s and i to interval [0,1]
+    i = i > 0.0f ? (i < 1.0f ? i : 1.0f) : 0.0f;
+
+    // Math! Thanks in part to Kyle Miller.
+    if(h < 2.09439f) {
+        r = 65535.0f * i/3.0f *(1.0f + s * cos(h) / cosf(1.047196667f - h));
+        g = 65535.0f * i/3.0f *(1.0f + s *(1.0f - cosf(h) / cos(1.047196667f - h)));
+        b = 65535.0f * i/3.0f *(1.0f - s);
+    } else if(h < 4.188787) {
+        h = h - 2.09439;
+        g = 65535.0f * i/3.0f *(1.0f + s * cosf(h) / cosf(1.047196667f - h));
+        b = 65535.0f * i/3.0f *(1.0f + s * (1.0f - cosf(h) / cosf(1.047196667f - h)));
+        r = 65535.0f * i/3.0f *(1.0f - s);
+    } else {
+        h = h - 4.188787;
+        b = 65535.0f*i/3.0f * (1.0f + s * cosf(h) / cosf(1.047196667f - h));
+        r = 65535.0f*i/3.0f * (1.0f + s * (1.0f - cosf(h) / cosf(1.047196667f - h)));
+        g = 65535.0f*i/3.0f * (1.0f - s);
+    }
+    *r_out = r > 65535 ? 65535 : r;
+    *g_out = g > 65535 ? 65535 : g;
+    *b_out = b > 65535 ? 65535 : b;
+}
+
+void lcd_backlight_color(uint8_t hue, uint8_t saturation, uint8_t intensity) {
+    uint16_t r, g, b;
+    float hue_f = 360.0f * (float)hue / 255.0f;
+    float saturation_f = (float)saturation / 255.0f;
+    float intensity_f = (float)intensity / 255.0f;
+    intensity_f *= (float)current_brightness / 255.0f;
+    hsi_to_rgb(hue_f, saturation_f, intensity_f, &r, &g, &b);
+	current_hue = hue;
+	current_saturation = saturation;
+	current_intensity = intensity;
+	lcd_backlight_hal_color(r, g, b);
+}
+
+void lcd_backlight_brightness(uint8_t b) {
+    current_brightness = b;
+    lcd_backlight_color(current_hue, current_saturation, current_intensity);
+}