1 files changed, 59 insertions, 0 deletions
diff --git a/src/rocksdb/table/data_block_footer.cc b/src/rocksdb/table/data_block_footer.cc
new file mode 100644
index 00000000..cb9e1438
--- /dev/null
+++ b/src/rocksdb/table/data_block_footer.cc
@@ -0,0 +1,59 @@
+//  Copyright (c) 2011-present, Facebook, Inc.  All rights reserved.
+//  This source code is licensed under both the GPLv2 (found in the
+//  COPYING file in the root directory) and Apache 2.0 License
+//  (found in the LICENSE.Apache file in the root directory).
+//
+// Copyright (c) 2011 The LevelDB Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file. See the AUTHORS file for names of contributors.
+
+#include "data_block_footer.h"
+
+#include "rocksdb/table.h"
+
+namespace rocksdb {
+
+const int kDataBlockIndexTypeBitShift = 31;
+
+// 0x7FFFFFFF
+const uint32_t kMaxNumRestarts = (1u << kDataBlockIndexTypeBitShift) - 1u;
+
+// 0x7FFFFFFF
+const uint32_t kNumRestartsMask = (1u << kDataBlockIndexTypeBitShift) - 1u;
+
+uint32_t PackIndexTypeAndNumRestarts(
+    BlockBasedTableOptions::DataBlockIndexType index_type,
+    uint32_t num_restarts) {
+  if (num_restarts > kMaxNumRestarts) {
+    assert(0);  // mute travis "unused" warning
+  }
+
+  uint32_t block_footer = num_restarts;
+  if (index_type == BlockBasedTableOptions::kDataBlockBinaryAndHash) {
+    block_footer |= 1u << kDataBlockIndexTypeBitShift;
+  } else if (index_type != BlockBasedTableOptions::kDataBlockBinarySearch) {
+    assert(0);
+  }
+
+  return block_footer;
+}
+
+void UnPackIndexTypeAndNumRestarts(
+    uint32_t block_footer,
+    BlockBasedTableOptions::DataBlockIndexType* index_type,
+    uint32_t* num_restarts) {
+  if (index_type) {
+    if (block_footer & 1u << kDataBlockIndexTypeBitShift) {
+      *index_type = BlockBasedTableOptions::kDataBlockBinaryAndHash;
+    } else {
+      *index_type = BlockBasedTableOptions::kDataBlockBinarySearch;
+    }
+  }
+
+  if (num_restarts) {
+    *num_restarts = block_footer & kNumRestartsMask;
+    assert(*num_restarts <= kMaxNumRestarts);
+  }
+}
+
+}  // namespace rocksdb