encodeHD108()

template<typename InputIterator, typename OutputIterator>

void fl::encodeHD108	(	InputIterator	first,
		InputIterator	last,
		OutputIterator	out,
		u8	global_brightness = 255 )

Encode pixel data in HD108 format with global brightness.

Template Parameters

InputIterator	Iterator yielding fl::array<u8, 3> (3 bytes in wire order)
OutputIterator	Output iterator accepting uint8_t

Parameters

first	Iterator to first pixel
last	Iterator past last pixel
out	Output iterator for encoded bytes
global_brightness	Accepted and ignored. HD108's per-channel 5-bit gains are pinned at maximum (31) for precision and brightness is expected to be applied to the 16-bit values before encoding, so this argument reaches neither the header nor the payload. Kept for source compatibility; the sole in-tree caller passes 255 and pre-scales. Passing anything else does not dim (FastLED#4042).

Note

Uses gamma 2.8 correction for 16-bit RGB

HD108 uses RGB wire order: pixel[0]=Red, pixel[1]=Green, pixel[2]=Blue

Definition at line 43 of file hd108.h.

                                                          {
    // Start frame: 64 bits (8 bytes) of 0x00
    for (int i = 0; i < 8; i++) {
        *out++ = 0x00;
    }
 
    // Compute brightness header bytes (cached for all LEDs)
    u8 f0, f1;
    hd108BrightnessHeader(global_brightness, &f0, &f1);
 
    // LED data: 2-byte header + 6-byte RGB16 (count as we go)
    size_t num_leds = 0;
    while (first != last) {
        const fl::array<u8, BYTES_PER_PIXEL_RGB>& pixel = *first;
 
        // Apply gamma correction (2.8) to 16-bit (RGB order: 0=R, 1=G, 2=B)
        u16 r16 = hd108GammaCorrect(pixel[0]);  // Red
        u16 g16 = hd108GammaCorrect(pixel[1]);  // Green
        u16 b16 = hd108GammaCorrect(pixel[2]);  // Blue
 
        // Transmit: 2 header + 6 color bytes (16-bit RGB, big-endian)
        *out++ = f0;
        *out++ = f1;
        *out++ = static_cast<u8>(r16 >> 8);
        *out++ = static_cast<u8>(r16 & 0xFF);
        *out++ = static_cast<u8>(g16 >> 8);
        *out++ = static_cast<u8>(g16 & 0xFF);
        *out++ = static_cast<u8>(b16 >> 8);
        *out++ = static_cast<u8>(b16 & 0xFF);
 
        ++first;
        ++num_leds;
    }
 
    // End frame: (num_leds / 2) + 4 bytes of 0xFF
    const size_t latch = num_leds / 2 + 4;
    for (size_t i = 0; i < latch; i++) {
        *out++ = 0xFF;
    }
}

References FL_NO_EXCEPT, hd108BrightnessHeader(), and hd108GammaCorrect().

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