add some docs

hal/src/main/native/athena/AddressableLEDSimd.h

@@ -78,6 +78,17 @@ void RGBConvert_16(const uint8_t* src, uint8_t* dst) {
   }
 }
 
+/**
+ * Copies 8 pixels from src to dst, converting from RGB(?) to order. Optimizes based on alignment of input and output arrays specified by inAlign and outAlign
+ * @tparam order the color order to convert to
+ * @tparam inAlign whether src is aligned to the size of a NEON register (16 bytes)
+ * @tparam outAlign whether dst is aligned to the size of a NEON register (16 bytes)
+ * @param[in] src The source array
+ * @param[out] dst the destination array
+ * @pre src and dst must contain at least 32 bytes (8 pixels)
+ * @pre if inAlign is true, src must be 16 byte aligned
+ * @pre if outAlign is true, src muts be 16 byte aligned
+ */
 template <HAL_AddressableLEDColorOrder order, bool inAlign, bool outAlign>
 void RGBConvert_8(const uint8_t* src, uint8_t* dst) {
   switch (order) {
@@ -98,7 +109,13 @@ void RGBConvert_8(const uint8_t* src, uint8_t* dst) {
       break;
   }
 }
-
+/**
+ * Copies 1 pixel from in to out, converting from RGB to the specified order.
+ * @param[in] order the color order to convert to
+ * @param[in] in the source array
+ * @param[out] the destination array
+ * @pre in and out must contain at least 1 pixel.
+*/
 void RGBConvert_1(HAL_AddressableLEDColorOrder order, const uint8_t* in, uint8_t* out) {
   uint8_t tmp[4];
   std::memcpy(tmp, in, 4);
@@ -122,7 +139,18 @@ void RGBConvert_1(HAL_AddressableLEDColorOrder order, const uint8_t* in, uint8_t
       std::memcpy(out, in, 4);
   }
 }
-
+/**
+ * Copies len pixels from src to dst, converting from RGB(?) to order. Optimizes based on alignment of input and output arrays specified by inAlign and outAlign
+ * @tparam order the color order to convert to
+ * @tparam inAlign whether src is aligned to the size of a NEON register (16 bytes)
+ * @tparam outAlign whether dst is aligned to the size of a NEON register (16 bytes)
+ * @param[in] src The source array
+ * @param[out] dst the destination array
+ * @param[in] len the size (in pixels, len = (size in bytes) / 4)
+ * @pre src and dst must have at least len*4 capacity in bytes
+ * @pre if inAlign is true, src must be 16 byte aligned
+ * @pre if outAlign is true, src muts be 16 byte aligned
+ */
 template <HAL_AddressableLEDColorOrder order, bool inAlign, bool outAlign>
 void RGBConvert(const uint8_t* src, uint8_t* dst, size_t len) {
   if(len >= 16) {
@@ -147,13 +175,18 @@ void RGBConvert(const uint8_t* src, uint8_t* dst, size_t len) {
     for(size_t i = 0; i < len; i += 4) {
       RGBConvert_1(order, src + i, dst + i);
     }
+    // we could also use neon single lane instructions
     // https://developer.arm.com/documentation/ddi0406/c/Application-Level-Architecture/Instruction-Details/Alphabetical-list-of-instructions/VLD4--single-4-element-structure-to-all-lanes-
     // https://developer.arm.com/documentation/102474/0100/Fundamentals-of-Armv8-Neon-technology/Registers--vectors--lanes-and-elements
     // vld4_lane_u8
   }
 
 }
 
+/**
+ * Copies pixelCount pixels from src to dst, converting from RGB to the specified order 
+ * 
+ */
 template <HAL_AddressableLEDColorOrder order>
 void RGBConvert(const uint8_t* src, uint8_t* dst, size_t pixelCount) {
   if (Aligned(src) && Aligned(dst)) {