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Diffstat (limited to 'src/mongo/bson/util/simple8b.h')
-rw-r--r-- | src/mongo/bson/util/simple8b.h | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/src/mongo/bson/util/simple8b.h b/src/mongo/bson/util/simple8b.h new file mode 100644 index 00000000000..2c6e4207698 --- /dev/null +++ b/src/mongo/bson/util/simple8b.h @@ -0,0 +1,64 @@ +/** + * Copyright (C) 2021-present MongoDB, Inc. + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the Server Side Public License, version 1, + * as published by MongoDB, Inc. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * Server Side Public License for more details. + * + * You should have received a copy of the Server Side Public License + * along with this program. If not, see + * <http://www.mongodb.com/licensing/server-side-public-license>. + * + * As a special exception, the copyright holders give permission to link the + * code of portions of this program with the OpenSSL library under certain + * conditions as described in each individual source file and distribute + * linked combinations including the program with the OpenSSL library. You + * must comply with the Server Side Public License in all respects for + * all of the code used other than as permitted herein. If you modify file(s) + * with this exception, you may extend this exception to your version of the + * file(s), but you are not obligated to do so. If you do not wish to do so, + * delete this exception statement from your version. If you delete this + * exception statement from all source files in the program, then also delete + * it in the license file. + */ + +#pragma once + +#include <cmath> +#include <iostream> +#include <vector> + + +namespace mongo { + +/** + * As of now, Simple8b is a static class that can encode a series of integers and a selector value + * into a single 64 bit Simple8b word. + */ +class Simple8b { +public: + // A valid Simple8b should never have a selector value of 1, so we will use it as an error code. + static const uint64_t errCode = 0x1000000000000000; + + /** + * encodeSimple8b takes a selector and a vector of integers to be compressed into a 64 bit word. + * If there are wasted bits, it will be at the very right side. + * For now, we will assume that all ints in the vector are greater or equal to zero. + * We will also assume that the selector and all values will fit into the 64 bit word. + * Returns the encoded Simple8b word if the inputs are valid and errCode otherwise. + */ + static uint64_t encodeSimple8b(uint8_t selector, const std::vector<uint64_t>& values); + + /** + * decodeSimple8b decodes a simple8b word into a vector of integers. + * Only when the selector is invalid will the returned vector be empty. + */ + static std::vector<uint64_t> decodeSimple8b(uint64_t simple8bWord); +}; + +} // namespace mongo |