common.hpp

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// SPDX-FileCopyrightText: 2022-2023 Dennis Gläser <dennis.glaeser@iws.uni-stuttgart.de>
// SPDX-License-Identifier: MIT
#ifndef GRIDFORMAT_COMPRESSION_COMMON_HPP_
#define GRIDFORMAT_COMPRESSION_COMMON_HPP_
 
#include <vector>
#include <utility>
#include <numeric>
 
#include <gridformat/common/exceptions.hpp>
#include <gridformat/common/serialization.hpp>
 
namespace GridFormat::Compression {
 
 
inline constexpr std::size_t default_block_size = (1 << 15);  
 
template<std::integral HeaderType = std::size_t>
struct Blocks {
    const HeaderType block_size;
    const HeaderType residual_block_size;
    const HeaderType number_of_blocks;
 
    Blocks(HeaderType size_in_bytes, HeaderType block_size)
    : block_size{block_size}
    , residual_block_size{size_in_bytes%block_size}
    , number_of_blocks{residual_block_size ? size_in_bytes/block_size + 1 : size_in_bytes/block_size}
    {}
};
 
template<std::integral HeaderType = std::size_t>
struct CompressedBlocks {
    const HeaderType block_size;
    const HeaderType residual_block_size;
    const HeaderType number_of_blocks;
    const std::vector<HeaderType> compressed_block_sizes;
 
    CompressedBlocks(const Blocks<HeaderType>& blocks,
                     std::vector<HeaderType>&& comp_block_sizes)
    : block_size{blocks.block_size}
    , residual_block_size{blocks.residual_block_size}
    , number_of_blocks{blocks.number_of_blocks}
    , compressed_block_sizes{std::move(comp_block_sizes)} {
        if (compressed_block_sizes.size() != number_of_blocks)
            throw SizeError("Mismatch between blocks and number of compressed blocks");
    }
 
    std::size_t compressed_size() const {
        return std::accumulate(
            compressed_block_sizes.begin(),
            compressed_block_sizes.end(),
            1
        );
    }
};
 
 
}  // end namespace GridFormat::Compression
 
#endif  // GRIDFORMAT_COMPRESSION_COMMON_HPP_