Function EmitCopy

snappy.cc:701–729

template <bool len_less_than_12>
static inline char* EmitCopy(char* op, size_t offset, size_t len) {
  assert(len_less_than_12 == (len < 12));
  if (len_less_than_12) {
    return EmitCopyAtMost64</*len_less_than_12=*/true>(op, offset, len);
  } else {
    // A special case for len <= 64 might help, but so far measurements suggest
    // it's in the noise.

    // Emit 64 byte copies but make sure to keep at least four bytes reserved.
    while (SNAPPY_PREDICT_FALSE(len >= 68)) {
      op = EmitCopyAtMost64</*len_less_than_12=*/false>(op, offset, 64);
      len -= 64;
    }

    // One or two copies will now finish the job.
    if (len > 64) {
      op = EmitCopyAtMost64</*len_less_than_12=*/false>(op, offset, 60);
      len -= 60;
    }

    // Emit remainder.
    if (len < 12) {
      op = EmitCopyAtMost64</*len_less_than_12=*/true>(op, offset, len);
    } else {
      op = EmitCopyAtMost64</*len_less_than_12=*/false>(op, offset, len);
    }
    return op;
  }
}

bool GetUncompressedLength(const char* start, size_t n, size_t* result) {
  uint32_t v = 0;