122 lines
3.7 KiB
C++
122 lines
3.7 KiB
C++
/*
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* Copyright 2003-2019 Max Kellermann <max.kellermann@gmail.com>
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*
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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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*
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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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*
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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 the
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* documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* 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
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#ifndef DYNAMIC_FIFO_BUFFER_HXX
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#define DYNAMIC_FIFO_BUFFER_HXX
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#include "ForeignFifoBuffer.hxx"
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/**
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* A first-in-first-out buffer: you can append data at the end, and
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* read data from the beginning. This class automatically shifts the
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* buffer as needed. It is not thread safe.
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*/
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template<typename T>
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class DynamicFifoBuffer : protected ForeignFifoBuffer<T> {
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public:
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using typename ForeignFifoBuffer<T>::size_type;
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using typename ForeignFifoBuffer<T>::pointer_type;
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using typename ForeignFifoBuffer<T>::const_pointer_type;
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using typename ForeignFifoBuffer<T>::Range;
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/**
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* Construct without allocating a buffer.
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*/
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explicit constexpr DynamicFifoBuffer(std::nullptr_t n) noexcept
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:ForeignFifoBuffer<T>(n) {}
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/**
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* Allocate a buffer with the given capacity.
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*/
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explicit DynamicFifoBuffer(size_type _capacity) noexcept
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:ForeignFifoBuffer<T>(new T[_capacity], _capacity) {}
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~DynamicFifoBuffer() noexcept {
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delete[] GetBuffer();
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}
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DynamicFifoBuffer(const DynamicFifoBuffer &) = delete;
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using ForeignFifoBuffer<T>::GetCapacity;
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using ForeignFifoBuffer<T>::Clear;
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using ForeignFifoBuffer<T>::empty;
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using ForeignFifoBuffer<T>::IsFull;
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using ForeignFifoBuffer<T>::GetAvailable;
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using ForeignFifoBuffer<T>::Read;
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using ForeignFifoBuffer<T>::Consume;
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using ForeignFifoBuffer<T>::Write;
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using ForeignFifoBuffer<T>::Append;
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void Grow(size_type new_capacity) noexcept {
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assert(new_capacity > GetCapacity());
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T *old_data = GetBuffer();
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T *new_data = new T[new_capacity];
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ForeignFifoBuffer<T>::MoveBuffer(new_data, new_capacity);
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delete[] old_data;
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}
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void WantWrite(size_type n) noexcept {
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if (ForeignFifoBuffer<T>::WantWrite(n))
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/* we already have enough space */
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return;
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const size_type in_use = GetAvailable();
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const size_type required_capacity = in_use + n;
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size_type new_capacity = GetCapacity();
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do {
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new_capacity <<= 1;
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} while (new_capacity < required_capacity);
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Grow(new_capacity);
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}
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/**
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* Write data to the buffer, growing it as needed. Returns a
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* writable pointer.
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*/
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pointer_type Write(size_type n) noexcept {
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WantWrite(n);
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return Write().data;
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}
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/**
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* Append data to the buffer, growing it as needed.
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*/
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void Append(const_pointer_type p, size_type n) noexcept {
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std::copy_n(p, n, Write(n));
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Append(n);
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}
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protected:
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using ForeignFifoBuffer<T>::GetBuffer;
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};
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#endif
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