sk9822.h

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#pragma once

 
#include "fl/stl/stdint.h"
#include "fl/stl/array.h"
#include "fl/chipsets/encoders/encoder_utils.h"
#include "fl/chipsets/encoders/encoder_constants.h"
#include "fl/stl/compiler_control.h"
#include "fl/stl/noexcept.h"
 
namespace fl {

template <typename InputIterator, typename OutputIterator>
void encodeSK9822(InputIterator first, InputIterator last, OutputIterator out,
                  u8 global_brightness = 31) FL_NO_EXCEPT {
    // Clamp brightness to 5-bit range
    global_brightness = global_brightness & 0x1F;
 
    // Start frame: 4 bytes of 0x00
    *out++ = 0x00;
    *out++ = 0x00;
    *out++ = 0x00;
    *out++ = 0x00;
 
    // LED data: brightness header + BGR (count as we go)
    size_t num_leds = 0;
    while (first != last) {
        const fl::array<u8, BYTES_PER_PIXEL_RGB>& pixel = *first;
        *out++ = 0xE0 | global_brightness;
        *out++ = pixel[0];  // Index 0 (BGR order: Blue)
        *out++ = pixel[1];  // Index 1 (BGR order: Green)
        *out++ = pixel[2];  // Index 2 (BGR order: Red)
        ++first;
        ++num_leds;
    }
 
    // The vendor datasheet requires all ones for the end clocks. These clocks
    // shift the final LED frame through a long cascade; a zero frame is not a
    // substitute because it is itself a valid start-frame pattern.
    size_t end_dwords = (num_leds / 32) + 1;
    for (size_t i = 0; i < end_dwords * 4; i++) {
        *out++ = 0xFF;
    }
}

template <typename InputIterator, typename BrightnessIterator, typename OutputIterator>
void encodeSK9822_HD(InputIterator first, InputIterator last,
                     BrightnessIterator brightness_first, OutputIterator out) FL_NO_EXCEPT {
    // Start frame: 4 bytes of 0x00
    *out++ = 0x00;
    *out++ = 0x00;
    *out++ = 0x00;
    *out++ = 0x00;
 
    // LED data: brightness header + BGR (per-LED brightness, count as we go)
    size_t num_leds = 0;
    while (first != last) {
        const fl::array<u8, BYTES_PER_PIXEL_RGB>& pixel = *first;
        u8 brightness_8bit = *brightness_first;
        u8 brightness_5bit = mapBrightness8to5(brightness_8bit);
 
        *out++ = 0xE0 | brightness_5bit;
        *out++ = pixel[0];  // Index 0 (BGR order: Blue)
        *out++ = pixel[1];  // Index 1 (BGR order: Green)
        *out++ = pixel[2];  // Index 2 (BGR order: Red)
 
        ++first;
        ++brightness_first;
        ++num_leds;
    }
 
    // See encodeSK9822(): the end clocks are all ones.
    size_t end_dwords = (num_leds / 32) + 1;
    for (size_t i = 0; i < end_dwords * 4; i++) {
        *out++ = 0xFF;
    }
}

template <typename InputIterator, typename OutputIterator>
FL_NO_INLINE_IF_AVR
void encodeSK9822_AutoBrightness(InputIterator first, InputIterator last,
                                 OutputIterator out) FL_NO_EXCEPT {
    if (first == last) {
        // Keep zero LEDs as a full frame, matching the non-auto encoder.
        *out++ = 0x00; *out++ = 0x00; *out++ = 0x00; *out++ = 0x00;
        *out++ = 0xFF; *out++ = 0xFF; *out++ = 0xFF; *out++ = 0xFF;
        return;
    }
 
    // Start frame
    *out++ = 0x00;
    *out++ = 0x00;
    *out++ = 0x00;
    *out++ = 0x00;
 
    // Extract global brightness from first pixel
    const fl::array<u8, BYTES_PER_PIXEL_RGB>& first_pixel = *first;
    const u16 maxBrightness = 0x1F;
    // Use sequential comparisons to avoid nested fl::max (helps AVR register allocation)
    u8 max_rg = (first_pixel[2] > first_pixel[1]) ? first_pixel[2] : first_pixel[1];
    u8 max_component = (max_rg > first_pixel[0]) ? max_rg : first_pixel[0];
    u16 brightness = ((((u16)max_component + 1) * maxBrightness - 1) >> 8) + 1;
    u8 global_brightness = static_cast<u8>(brightness);
 
    // Write first LED with extracted brightness (BGR order: 0=B, 1=G, 2=R)
    u8 s0 = (maxBrightness * first_pixel[2] + (brightness >> 1)) / brightness;  // Red
    u8 s1 = (maxBrightness * first_pixel[1] + (brightness >> 1)) / brightness;  // Green
    u8 s2 = (maxBrightness * first_pixel[0] + (brightness >> 1)) / brightness;  // Blue
 
    *out++ = 0xE0 | (global_brightness & 0x1F);
    *out++ = s2;  // Blue
    *out++ = s1;  // Green
    *out++ = s0;  // Red
    ++first;
 
    // Write remaining LEDs (count as we go)
    size_t num_leds = 1;  // Already wrote first pixel
    while (first != last) {
        const fl::array<u8, BYTES_PER_PIXEL_RGB>& pixel = *first;
        *out++ = 0xE0 | (global_brightness & 0x1F);
        *out++ = pixel[0];  // Index 0 (BGR order: Blue)
        *out++ = pixel[1];  // Index 1 (BGR order: Green)
        *out++ = pixel[2];  // Index 2 (BGR order: Red)
        ++first;
        ++num_leds;
    }
 
    // End frame: all ones clock the final data through the cascade.
    size_t end_dwords = (num_leds / 32) + 1;
    for (size_t i = 0; i < end_dwords * 4; i++) {
        *out++ = 0xFF;
    }
}
 
} // namespace fl