ceph/src/zstd/contrib/pzstd/SkippableFrame.cpp

   1 /**
   2  * Copyright (c) 2016-present, Facebook, Inc.
   3  * All rights reserved.
   4  *
   5  * This source code is licensed under the BSD-style license found in the
   6  * LICENSE file in the root directory of this source tree. An additional grant
   7  * of patent rights can be found in the PATENTS file in the same directory.
   8  */
   9 #include "SkippableFrame.h"
  10 #include "mem.h"
  11 #include "utils/Range.h"
  12
  13 #include <cstdio>
  14
  15 using namespace pzstd;
  16
  17 SkippableFrame::SkippableFrame(std::uint32_t size) : frameSize_(size) {
  18   MEM_writeLE32(data_.data(), kSkippableFrameMagicNumber);
  19   MEM_writeLE32(data_.data() + 4, kFrameContentsSize);
  20   MEM_writeLE32(data_.data() + 8, frameSize_);
  21 }
  22
  23 /* static */ std::size_t SkippableFrame::tryRead(ByteRange bytes) {
  24   if (bytes.size() < SkippableFrame::kSize ||
  25       MEM_readLE32(bytes.begin()) != kSkippableFrameMagicNumber ||
  26       MEM_readLE32(bytes.begin() + 4) != kFrameContentsSize) {
  27     return 0;
  28   }
  29   return MEM_readLE32(bytes.begin() + 8);
  30 }