transpose_8lane_inline()

void fl::transpose_8lane_inline ( const u8 *const lanes[8], u8 * output, size_t num_bytes )

inline

Low-level bit-interleaving primitive for 8 lanes (ISR-safe)

Transposes 8 input bytes into 8-way interleaved format with optimized bit extraction. This function is ISR-safe: no allocations, no exceptions, minimal overhead. Inline functions are automatically placed where needed - no IRAM_ATTR required.

Parameters

lanes	Array of 8 lane byte pointers
output	Output buffer (must have space for num_bytes * 8 bytes)
num_bytes	Number of bytes to transpose per lane

Note

Inline function - inlined at call site (including ISR contexts)

Output size is num_bytes * 8

Examples

/home/runner/work/FastLED/FastLED/src/fl/math/transposition.h.

Definition at line 382 of file transposition.h.

              {
    for (size_t byte_idx = 0; byte_idx < num_bytes; byte_idx++) {
        // Pack 8 bytes into a single 64-bit register
        // This reduces register pressure and enables parallel bit extraction
        u64 packed =
            ((u64)lanes[0][byte_idx] << 0)  |
            ((u64)lanes[1][byte_idx] << 8)  |
            ((u64)lanes[2][byte_idx] << 16) |
            ((u64)lanes[3][byte_idx] << 24) |
            ((u64)lanes[4][byte_idx] << 32) |
            ((u64)lanes[5][byte_idx] << 40) |
            ((u64)lanes[6][byte_idx] << 48) |
            ((u64)lanes[7][byte_idx] << 56);
 
        u8* dest = &output[byte_idx * 8];
 
        // Extract bits in parallel (compiler can optimize independent shifts)
        for (int bit = 7; bit >= 0; bit--) {
            dest[7 - bit] =
                ((packed >> (bit + 0))  & 0x01) << 0 |
                ((packed >> (bit + 8))  & 0x01) << 1 |
                ((packed >> (bit + 16)) & 0x01) << 2 |
                ((packed >> (bit + 24)) & 0x01) << 3 |
                ((packed >> (bit + 32)) & 0x01) << 4 |
                ((packed >> (bit + 40)) & 0x01) << 5 |
                ((packed >> (bit + 48)) & 0x01) << 6 |
                ((packed >> (bit + 56)) & 0x01) << 7;
        }
    }
}

References FL_NOEXCEPT.

Referenced by fl::SPITransposer::transpose8().

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