forked from premiere/premiere-libtorrent
143 lines
4.1 KiB
C++
143 lines
4.1 KiB
C++
/*
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Copyright (c) 2010-2016, Arvid Norberg, Daniel Wallin.
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All rights reserved.
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Redistribution and use in source and binary forms, with or without
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modification, are permitted provided that the following conditions
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are met:
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* Redistributions of source code must retain the above copyright
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notice, this list of conditions and the following disclaimer.
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* Redistributions in binary form must reproduce the above copyright
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notice, this list of conditions and the following disclaimer in
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the documentation and/or other materials provided with the distribution.
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* Neither the name of the author nor the names of its
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contributors may be used to endorse or promote products derived
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from this software without specific prior written permission.
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THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef TORRENT_PACKET_BUFFER_HPP_INCLUDED
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#define TORRENT_PACKET_BUFFER_HPP_INCLUDED
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#include "libtorrent/config.hpp"
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#include <cstdint>
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#include <cstddef>
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namespace libtorrent
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{
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// this is a circular buffer that automatically resizes
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// itself as elements are inserted. Elements are indexed
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// by integers and are assumed to be sequential. Unless the
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// old elements are removed when new elements are inserted,
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// the buffer will be resized.
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// m_capacity is the number of elements in m_array
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// and must be an even 2^x.
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// m_first is the lowest index that has an element
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// it also determines which indices the other slots
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// refers to. Since it's a circular buffer, it wraps
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// around. For example
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// m_first = 9
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// | refers to index 14
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// | |
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// V V
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// | | | | | | | | | | | | | | | | | mask = (m_capacity-1)
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// +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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// ^
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// |
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// refers to index 15
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// whenever the element at the cursor is removed, the
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// cursor is bumped to the next occupied element
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class TORRENT_EXTRA_EXPORT packet_buffer_impl
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{
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public:
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typedef std::uint32_t index_type;
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packet_buffer_impl();
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~packet_buffer_impl();
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void* insert(index_type idx, void* value);
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std::size_t size() const
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{ return m_size; }
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std::size_t capacity() const
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{ return m_capacity; }
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void* at(index_type idx) const;
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void* remove(index_type idx);
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void reserve(std::size_t size);
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index_type cursor() const
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{ return m_first; }
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index_type span() const
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{ return (m_last - m_first) & 0xffff; }
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#if TORRENT_USE_INVARIANT_CHECKS
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void check_invariant() const;
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#endif
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private:
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void** m_storage;
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std::size_t m_capacity;
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// this is the total number of elements that are occupied
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// in the array
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std::size_t m_size;
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// This defines the first index that is part of the m_storage.
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// last is one passed the last used slot
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index_type m_first;
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index_type m_last;
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};
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template <typename T>
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class packet_buffer : packet_buffer_impl
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{
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public:
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using packet_buffer_impl::index_type;
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using packet_buffer_impl::size;
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using packet_buffer_impl::capacity;
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using packet_buffer_impl::reserve;
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using packet_buffer_impl::cursor;
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using packet_buffer_impl::span;
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T* insert(index_type i, T* p)
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{
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return static_cast<T*>(packet_buffer_impl::insert(i, p));
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}
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T* at(index_type idx) const
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{ return static_cast<T*>(packet_buffer_impl::at(idx)); }
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T* remove(index_type idx)
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{ return static_cast<T*>(packet_buffer_impl::remove(idx)); }
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};
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}
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#endif // TORRENT_PACKET_BUFFER_HPP_INCLUDED
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