1 files changed, 68 insertions, 0 deletions
diff --git a/c/enc/matching_tag_mask.h b/c/enc/matching_tag_mask.h
new file mode 100644
index 0000000..c166255
--- /dev/null
+++ b/c/enc/matching_tag_mask.h
@@ -0,0 +1,68 @@
+#ifndef THIRD_PARTY_BROTLI_ENC_MATCHING_TAG_MASK_H_
+#define THIRD_PARTY_BROTLI_ENC_MATCHING_TAG_MASK_H_
+
+#include "../common/platform.h"
+
+#if defined(__SSE2__) || defined(_M_AMD64) || (defined (_M_IX86) && defined(_M_IX86_FP) && (_M_IX86_FP >= 2))
+#define SUPPORTS_SSE_2
+#endif
+
+#if defined(SUPPORTS_SSE_2)
+#include <immintrin.h>
+#endif
+
+
+static BROTLI_INLINE uint64_t GetMatchingTagMask(
+    size_t chunk_count, const uint8_t tag,
+    const uint8_t* BROTLI_RESTRICT tag_bucket, const size_t head) {
+  uint64_t matches = 0;
+#if defined(SUPPORTS_SSE_2)
+  const __m128i comparison_mask = _mm_set1_epi8((char)tag);
+  size_t i;
+  for (i = 0; i < chunk_count && i < 4; i++) {
+    const __m128i chunk =
+        _mm_loadu_si128((const __m128i*)(const void*)(tag_bucket + 16 * i));
+    const __m128i equal_mask = _mm_cmpeq_epi8(chunk, comparison_mask);
+    matches |= (uint64_t)_mm_movemask_epi8(equal_mask) << 16 * i;
+  }
+#else
+  const int chunk_size = sizeof(size_t);
+  const size_t shift_amount = ((chunk_size * 8) - chunk_size);
+  const size_t xFF = ~((size_t)0);
+  const size_t x01 = xFF / 0xFF;
+  const size_t x80 = x01 << 7;
+  const size_t splat_char = tag * x01;
+  int i = ((int)chunk_count * 16) - chunk_size;
+  BROTLI_DCHECK((sizeof(size_t) == 4) || (sizeof(size_t) == 8));
+#if BROTLI_LITTLE_ENDIAN
+  const size_t extractMagic = (xFF / 0x7F) >> chunk_size;
+  do {
+      size_t chunk = BrotliUnalignedReadSizeT(&tag_bucket[i]);
+      chunk ^= splat_char;
+      chunk = (((chunk | x80) - x01) | chunk) & x80;
+      matches <<= chunk_size;
+      matches |= (chunk * extractMagic) >> shift_amount;
+      i -= chunk_size;
+  } while (i >= 0);
+#else
+  const size_t msb = xFF ^ (xFF >> 1);
+  const size_t extractMagic = (msb / 0x1FF) | msb;
+  do {
+      size_t chunk = BrotliUnalignedReadSizeT(&tag_bucket[i]);
+      chunk ^= splat_char;
+      chunk = (((chunk | x80) - x01) | chunk) & x80;
+      matches <<= chunk_size;
+      matches |= ((chunk >> 7) * extractMagic) >> shift_amount;
+      i -= chunk_size;
+  } while (i >= 0);
+#endif
+  matches = ~matches;
+#endif
+  if (chunk_count == 1) return BrotliRotateRight16((uint16_t)matches, head);
+  if (chunk_count == 2) return BrotliRotateRight32((uint32_t)matches, head);
+  return BrotliRotateRight64(matches, head);
+}
+
+#undef SUPPORTS_SSE_2
+
+#endif  // THIRD_PARTY_BROTLI_ENC_MATCHING_TAG_MASK_H_