-
- // Process [0,31] bytes, such that start gets aligned to 32 bytes.
- const uint8_t *aligned_src = (const uint8_t *)(intptr_t(src + 31) & ~31);
- if (aligned_src != src) {
- size_t n2 = aligned_src - src;
- memcpy_interleaved(dest1, dest2, src, n2);
- dest1 += n2 / 2;
- dest2 += n2 / 2;
- if (n2 % 1) {
- swap(dest1, dest2);
- }
- src = aligned_src;
- consumed += n2;
- }
-
- // Make the length a multiple of 64.
- if (((limit - src) % 64) != 0) {
- limit -= 32;
- }
- assert(((limit - src) % 64) == 0);
-
-#if __AVX2__
- const __m256i * __restrict in = (const __m256i *)src;
- __m256i * __restrict out1 = (__m256i *)dest1;
- __m256i * __restrict out2 = (__m256i *)dest2;
-
- __m256i shuffle_cw = _mm256_set_epi8(
- 15, 13, 11, 9, 7, 5, 3, 1, 14, 12, 10, 8, 6, 4, 2, 0,
- 15, 13, 11, 9, 7, 5, 3, 1, 14, 12, 10, 8, 6, 4, 2, 0);
- while (in < (const __m256i *)limit) {
- // Note: For brevity, comments show lanes as if they were 2x64-bit (they're actually 2x128).
- __m256i data1 = _mm256_stream_load_si256(in); // AaBbCcDd EeFfGgHh
- __m256i data2 = _mm256_stream_load_si256(in + 1); // IiJjKkLl MmNnOoPp
-
- data1 = _mm256_shuffle_epi8(data1, shuffle_cw); // ABCDabcd EFGHefgh
- data2 = _mm256_shuffle_epi8(data2, shuffle_cw); // IJKLijkl MNOPmnop
-
- data1 = _mm256_permute4x64_epi64(data1, 0b11011000); // ABCDEFGH abcdefgh
- data2 = _mm256_permute4x64_epi64(data2, 0b11011000); // IJKLMNOP ijklmnop
-
- __m256i lo = _mm256_permute2x128_si256(data1, data2, 0b00100000);
- __m256i hi = _mm256_permute2x128_si256(data1, data2, 0b00110001);
-
- _mm256_storeu_si256(out1, lo);
- _mm256_storeu_si256(out2, hi);
-
- in += 2;
- ++out1;
- ++out2;
- consumed += 64;
- }
-#else
- const __m128i * __restrict in = (const __m128i *)src;
- __m128i * __restrict out1 = (__m128i *)dest1;
- __m128i * __restrict out2 = (__m128i *)dest2;
-
- __m128i mask_lower_byte = _mm_set1_epi16(0x00ff);
- while (in < (const __m128i *)limit) {
- __m128i data1 = _mm_load_si128(in);
- __m128i data2 = _mm_load_si128(in + 1);
- __m128i data1_lo = _mm_and_si128(data1, mask_lower_byte);
- __m128i data2_lo = _mm_and_si128(data2, mask_lower_byte);
- __m128i data1_hi = _mm_srli_epi16(data1, 8);
- __m128i data2_hi = _mm_srli_epi16(data2, 8);
- __m128i lo = _mm_packus_epi16(data1_lo, data2_lo);
- _mm_storeu_si128(out1, lo);
- __m128i hi = _mm_packus_epi16(data1_hi, data2_hi);
- _mm_storeu_si128(out2, hi);
-
- in += 2;
- ++out1;
- ++out2;
- consumed += 32;
- }
-#endif
-
- return consumed;