mirror of
https://github.com/transmission/transmission
synced 2024-12-23 08:13:27 +00:00
159 lines
4.4 KiB
C++
159 lines
4.4 KiB
C++
// This file Copyright © Mnemosyne LLC.
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// It may be used under GPLv2 (SPDX: GPL-2.0-only), GPLv3 (SPDX: GPL-3.0-only),
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// or any future license endorsed by Mnemosyne LLC.
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// License text can be found in the licenses/ folder.
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#pragma once
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#include <cstdint> // uint32_t, uint64_t
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#include "transmission.h"
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struct tr_block_info
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{
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private:
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uint64_t total_size_ = 0;
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uint32_t piece_size_ = 0;
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tr_piece_index_t n_pieces_ = 0;
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tr_block_index_t n_blocks_ = 0;
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// should be same type as BlockSize
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uint32_t final_block_size_ = 0;
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// should be same type as piece_size
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uint32_t final_piece_size_ = 0;
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public:
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static auto constexpr BlockSize = uint32_t{ 1024 * 16 };
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tr_block_info() noexcept = default;
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tr_block_info(uint64_t total_size_in, uint32_t piece_size_in) noexcept
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{
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init_sizes(total_size_in, piece_size_in);
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}
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void init_sizes(uint64_t total_size_in, uint32_t piece_size_in) noexcept;
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[[nodiscard]] constexpr auto block_count() const noexcept
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{
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return n_blocks_;
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}
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[[nodiscard]] constexpr auto block_size(tr_block_index_t block) const noexcept
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{
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return block + 1 == n_blocks_ ? final_block_size_ : BlockSize;
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}
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[[nodiscard]] constexpr auto piece_count() const noexcept
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{
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return n_pieces_;
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}
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[[nodiscard]] constexpr auto piece_size() const noexcept
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{
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return piece_size_;
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}
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[[nodiscard]] constexpr auto piece_size(tr_piece_index_t piece) const noexcept
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{
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return piece + 1 == n_pieces_ ? final_piece_size_ : piece_size();
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}
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[[nodiscard]] constexpr auto total_size() const noexcept
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{
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return total_size_;
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}
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struct Location
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{
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uint64_t byte = 0;
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tr_piece_index_t piece = 0;
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uint32_t piece_offset = 0;
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tr_block_index_t block = 0;
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uint32_t block_offset = 0;
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[[nodiscard]] constexpr bool operator==(Location const& that) const noexcept
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{
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return this->byte == that.byte;
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}
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[[nodiscard]] constexpr bool operator<(Location const& that) const noexcept
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{
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return this->byte < that.byte;
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}
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};
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// Location of the torrent's nth byte
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[[nodiscard]] constexpr auto byte_loc(uint64_t byte_idx) const noexcept
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{
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auto loc = Location{};
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if (is_initialized())
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{
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loc.byte = byte_idx;
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if (byte_idx == total_size()) // handle 0-byte files at the end of a torrent
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{
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loc.block = block_count() - 1;
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loc.piece = piece_count() - 1;
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}
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else
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{
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loc.block = byte_idx / BlockSize;
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loc.piece = byte_idx / piece_size();
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}
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loc.block_offset = static_cast<uint32_t>(loc.byte - (uint64_t{ loc.block } * BlockSize));
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loc.piece_offset = static_cast<uint32_t>(loc.byte - (uint64_t{ loc.piece } * piece_size()));
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}
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return loc;
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}
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// Location of the first byte in `block`.
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[[nodiscard]] constexpr auto block_loc(tr_block_index_t block) const noexcept
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{
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return byte_loc(uint64_t{ block } * BlockSize);
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}
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// Location of the first byte (+ optional offset and length) in `piece`
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[[nodiscard]] constexpr auto piece_loc(tr_piece_index_t piece, uint32_t offset = 0, uint32_t length = 0) const noexcept
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{
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return byte_loc(uint64_t{ piece } * piece_size() + offset + length);
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}
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[[nodiscard]] constexpr tr_block_span_t block_span_for_piece(tr_piece_index_t piece) const noexcept
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{
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if (!is_initialized())
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{
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return { 0U, 0U };
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}
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return { piece_loc(piece).block, piece_last_loc(piece).block + 1 };
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}
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[[nodiscard]] constexpr tr_byte_span_t byte_span_for_piece(tr_piece_index_t piece) const noexcept
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{
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if (!is_initialized())
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{
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return { 0U, 0U };
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}
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auto const offset = piece_loc(piece).byte;
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return { offset, offset + piece_size(piece) };
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}
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private:
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// Location of the last byte in `piece`.
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[[nodiscard]] constexpr Location piece_last_loc(tr_piece_index_t piece) const noexcept
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{
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return byte_loc(static_cast<uint64_t>(piece) * piece_size() + piece_size(piece) - 1);
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}
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[[nodiscard]] constexpr bool is_initialized() const noexcept
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{
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return piece_size_ != 0;
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}
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};
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