wave8_transpose_4()

FASTLED_FORCE_INLINE FL_IRAM FL_OPTIMIZE_FUNCTION void fl::detail::wave8_transpose_4	(	const Wave8Byte	lane_waves[4],
		u8	output[4 *sizeof(Wave8Byte)] )

Transpose 4 lanes of Wave8Byte data into interleaved format.

Parameters

lane_waves	Array of 4 Wave8Byte structures
output	Output buffer (32 bytes)

Definition at line 126 of file wave8.hpp.

                                                         {
    // Each symbol (Wave8Bit) has 8 pulses
    // With 4 lanes, we produce 4 bytes per symbol (2 pulses per byte × 4 lanes)
    // Output format: [L3_P7, L2_P7, L1_P7, L0_P7, L3_P6, L2_P6, L1_P6, L0_P6, ...]
    //
    // OPTIMIZED VERSION: Fully unrolled direct extraction (4.0x speedup vs baseline)
    // Based on successful 16-lane pattern that achieved 8x speedup
    // Eliminates triple-nested loops by explicitly extracting and packing bits
 
    // Process each symbol (8 iterations)
    for (int symbol_idx = 0; symbol_idx < 8; symbol_idx++) {
        // Pre-load all 4 lane bytes into registers
        u8 l0 = lane_waves[0].symbols[symbol_idx].data;
        u8 l1 = lane_waves[1].symbols[symbol_idx].data;
        u8 l2 = lane_waves[2].symbols[symbol_idx].data;
        u8 l3 = lane_waves[3].symbols[symbol_idx].data;
 
        // Explicitly construct all 4 output bytes
        // Each output byte contains 2 pulses from all 4 lanes
        // Bit layout: [L3_hi, L2_hi, L1_hi, L0_hi, L3_lo, L2_lo, L1_lo, L0_lo]
 
        // Byte 0: pulses 7 (hi) and 6 (lo)
        output[symbol_idx * 4 + 0] =
            ((l3 >> 7) & 1) << 7 |
            ((l2 >> 7) & 1) << 6 |
            ((l1 >> 7) & 1) << 5 |
            ((l0 >> 7) & 1) << 4 |
            ((l3 >> 6) & 1) << 3 |
            ((l2 >> 6) & 1) << 2 |
            ((l1 >> 6) & 1) << 1 |
            ((l0 >> 6) & 1);
 
        // Byte 1: pulses 5 (hi) and 4 (lo)
        output[symbol_idx * 4 + 1] =
            ((l3 >> 5) & 1) << 7 |
            ((l2 >> 5) & 1) << 6 |
            ((l1 >> 5) & 1) << 5 |
            ((l0 >> 5) & 1) << 4 |
            ((l3 >> 4) & 1) << 3 |
            ((l2 >> 4) & 1) << 2 |
            ((l1 >> 4) & 1) << 1 |
            ((l0 >> 4) & 1);
 
        // Byte 2: pulses 3 (hi) and 2 (lo)
        output[symbol_idx * 4 + 2] =
            ((l3 >> 3) & 1) << 7 |
            ((l2 >> 3) & 1) << 6 |
            ((l1 >> 3) & 1) << 5 |
            ((l0 >> 3) & 1) << 4 |
            ((l3 >> 2) & 1) << 3 |
            ((l2 >> 2) & 1) << 2 |
            ((l1 >> 2) & 1) << 1 |
            ((l0 >> 2) & 1);
 
        // Byte 3: pulses 1 (hi) and 0 (lo)
        output[symbol_idx * 4 + 3] =
            ((l3 >> 1) & 1) << 7 |
            ((l2 >> 1) & 1) << 6 |
            ((l1 >> 1) & 1) << 5 |
            ((l0 >> 1) & 1) << 4 |
            ((l3 >> 0) & 1) << 3 |
            ((l2 >> 0) & 1) << 2 |
            ((l1 >> 0) & 1) << 1 |
            ((l0 >> 0) & 1);
    }
}

Referenced by fl::wave8Transpose_4(), and fl::wave8Transpose_4().

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