Add PZstandard to contrib/

contrib/pzstd/SkippableFrame.cpp

@@ -0,0 +1,30 @@
+/**
+ * Copyright (c) 2016-present, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * LICENSE file in the root directory of this source tree. An additional grant
+ * of patent rights can be found in the PATENTS file in the same directory.
+ */
+#include "SkippableFrame.h"
+#include "common/mem.h"
+#include "utils/Range.h"
+
+#include <cstdio>
+
+using namespace pzstd;
+
+SkippableFrame::SkippableFrame(std::uint32_t size) : frameSize_(size) {
+  MEM_writeLE32(data_.data(), kSkippableFrameMagicNumber);
+  MEM_writeLE32(data_.data() + 4, kFrameContentsSize);
+  MEM_writeLE32(data_.data() + 8, frameSize_);
+}
+
+/* static */ std::size_t SkippableFrame::tryRead(ByteRange bytes) {
+  if (bytes.size() < SkippableFrame::kSize ||
+      MEM_readLE32(bytes.begin()) != kSkippableFrameMagicNumber ||
+      MEM_readLE32(bytes.begin() + 4) != kFrameContentsSize) {
+    return 0;
+  }
+  return MEM_readLE32(bytes.begin() + 8);
+}