136 lines
3.2 KiB
C++
136 lines
3.2 KiB
C++
/*
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* Copyright (C) 2003-2017 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 STATIC_FIFO_BUFFER_HXX
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#define STATIC_FIFO_BUFFER_HXX
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#include "WritableBuffer.hxx"
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#include <utility>
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#include <algorithm>
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#include <assert.h>
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#include <stddef.h>
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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<class T, size_t size>
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class StaticFifoBuffer {
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public:
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typedef size_t size_type;
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public:
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typedef WritableBuffer<T> Range;
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protected:
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size_type head = 0, tail = 0;
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T data[size];
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public:
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constexpr size_type GetCapacity() const {
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return size;
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}
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void Shift() {
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if (head == 0)
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return;
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assert(head <= size);
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assert(tail <= size);
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assert(tail >= head);
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std::move(data + head, data + tail, data);
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tail -= head;
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head = 0;
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}
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void Clear() {
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head = tail = 0;
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}
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bool IsEmpty() const {
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return head == tail;
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}
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bool IsFull() const {
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return head == 0 && tail == size;
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}
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/**
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* Prepares writing. Returns a buffer range which may be written.
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* When you are finished, call Append().
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*/
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Range Write() {
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if (IsEmpty())
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Clear();
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else if (tail == size)
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Shift();
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return Range(data + tail, size - tail);
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}
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/**
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* Expands the tail of the buffer, after data has been written to
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* the buffer returned by Write().
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*/
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void Append(size_type n) {
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assert(tail <= size);
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assert(n <= size);
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assert(tail + n <= size);
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tail += n;
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}
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/**
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* Return a buffer range which may be read. The buffer pointer is
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* writable, to allow modifications while parsing.
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*/
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Range Read() {
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return Range(data + head, tail - head);
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}
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/**
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* Marks a chunk as consumed.
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*/
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void Consume(size_type n) {
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assert(tail <= size);
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assert(head <= tail);
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assert(n <= tail);
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assert(head + n <= tail);
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head += n;
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}
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};
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#endif
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