wave8_transpose_16_bf1()

FASTLED_FORCE_INLINE FL_IRAM FL_OPTIMIZE_FUNCTION void fl::detail::wave8_transpose_16_bf1	(	const u8	lanes[16],
		u8	W0,
		u8	W1,
		u8	output[16 *sizeof(Wave8Byte)] )

BF1: chipset-aware direct encode for Wave8 16-lane (#2548 deep-dive).

Bypasses the byte_lut entirely by exploiting the algebraic identity: output_bit(s, p, lane) = M0_p XOR (input_bit_(7-s)_of_lane AND D_p) where W0/W1 are the bit-0 / bit-1 waveform patterns (chipset constants), M0_p = (W0 >> (7-p)) & 1, D_p = M0_p XOR M1_p. The bit-transpose of input lane bytes (giving the per-symbol column bytes) is computed ONCE by spread_transpose16_symbol — replacing the prior 8 calls (one per symbol) plus the 16 byte_lut expansions.

Bit-identical to wave8_transpose_16(expand(lanes_input), output). Works for ANY Wave8 chipset/timing — W0/W1 are derived from the byte_lut at runtime.

Measured 6 822 → 1 757 µs/frame (3.88× faster than pipe4, 5.49× vs baseline) when fused with pipe4 (#2548 final).

Definition at line 315 of file wave8.hpp.

                                                               {
    u8 d_mask[8];
    u8 m0_mask[8];
    const u8 D_byte = W0 ^ W1;
    for (int p = 0; p < 8; ++p) {
        const int shift = 7 - p;
        d_mask[p] = ((D_byte >> shift) & 1) ? 0xFFu : 0x00u;
        m0_mask[p] = ((W0 >> shift) & 1) ? 0xFFu : 0x00u;
    }
    // Bit-transpose: spread_transpose16_symbol on input bytes gives
    // cols[2s+h] = byte where bit L = bit(7-s) of lanes[L+8h].
    u8 cols[16];
    spread_transpose16_symbol(lanes, cols);
    for (int s = 0; s < 8; ++s) {
        const u8 col_lo = cols[2 * s + 0];
        const u8 col_hi = cols[2 * s + 1];
        for (int p = 0; p < 8; ++p) {
            output[s * 16 + p * 2 + 0] = m0_mask[p] ^ (col_lo & d_mask[p]);
            output[s * 16 + p * 2 + 1] = m0_mask[p] ^ (col_hi & d_mask[p]);
        }
    }
}

References spread_transpose16_symbol(), fl::W0, and fl::W1.

Referenced by fl::wave8Transpose_16_bf1().

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