Fix instability of hsv color around red

core/backlight/color.h

@@ -2,6 +2,8 @@
 
 #include <stdint.h>
 #include <cmath>
+#include "../util/math_utils.h"
+
 
 namespace core::backlight
 {
@@ -49,8 +51,13 @@ struct Color
      */
     static Color from_hsv(float hue, float saturation, float value)
     {
-        // This function was AI-generated
-        const float h = hue * 6.0f;
+        // Most of this function was AI-generated
+
+        // we need to clamp the hue as it otherwise manifests itself as a numerical
+        // instability around red.
+        const float hue_clamped = core::util::clamp(hue, 0.0001f, 0.9999f);
+
+        const float h = hue_clamped * 6.0f;
         const float f = h - floor(h);
         const float p = value * (1.0f - saturation);
         const float q = value * (1.0f - saturation * f);

core/util/math_utils.h

@@ -0,0 +1,17 @@
+#pragma once
+
+#include <cstdint>
+#include <cmath>
+#include <type_traits>
+
+namespace core::util
+{
+
+template<typename T>
+T clamp(T value, T min, T max)
+{
+    static_assert(std::is_arithmetic<T>::value, "T must be an arithmetic type");
+    return std::min(std::max(value, min), max);
+}
+
+}

docs/serialization_format.md

@@ -1,14 +1,15 @@
 # General
 
 - Everything is `uint16_t`
+- Everything is 0 indexed
 
 ## Action
 
 Action:
 ```
 [N, key_1, modifier_1, media_1, ..., key_N, modifier_N, media_N]
 ```
-where `N` is the sequence length.
+where `N` is the sequence length. A blank key is 0xF000, a blank modifier is 0xE000 and a blank media key is 0xE400.
 
 ## KeyMap