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+/*
+ * Copyright (C) 2003-2014 Max Kellermann <max@duempel.org>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * - Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ *
+ * - Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the
+ * distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
+ * OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#ifndef STATIC_FIFO_BUFFER_HPP
+#define STATIC_FIFO_BUFFER_HPP
+
+#include "WritableBuffer.hxx"
+
+#include <utility>
+#include <algorithm>
+
+#include <assert.h>
+#include <stddef.h>
+
+/**
+ * A first-in-first-out buffer: you can append data at the end, and
+ * read data from the beginning. This class automatically shifts the
+ * buffer as needed. It is not thread safe.
+ */
+template<class T, size_t size>
+class StaticFifoBuffer {
+public:
+ typedef size_t size_type;
+
+public:
+ typedef WritableBuffer<T> Range;
+
+protected:
+ size_type head, tail;
+ T data[size];
+
+public:
+ constexpr
+ StaticFifoBuffer():head(0), tail(0) {}
+
+ void Shift() {
+ if (head == 0)
+ return;
+
+ assert(head <= size);
+ assert(tail <= size);
+ assert(tail >= head);
+
+ std::move(data + head, data + tail, data);
+
+ tail -= head;
+ head = 0;
+ }
+
+ void Clear() {
+ head = tail = 0;
+ }
+
+ bool IsEmpty() const {
+ return head == tail;
+ }
+
+ bool IsFull() const {
+ return head == 0 && tail == size;
+ }
+
+ /**
+ * Prepares writing. Returns a buffer range which may be written.
+ * When you are finished, call append().
+ */
+ Range Write() {
+ if (IsEmpty())
+ Clear();
+ else if (tail == size)
+ Shift();
+
+ return Range(data + tail, size - tail);
+ }
+
+ /**
+ * Expands the tail of the buffer, after data has been written to
+ * the buffer returned by write().
+ */
+ void Append(size_type n) {
+ assert(tail <= size);
+ assert(n <= size);
+ assert(tail + n <= size);
+
+ tail += n;
+ }
+
+ /**
+ * Return a buffer range which may be read. The buffer pointer is
+ * writable, to allow modifications while parsing.
+ */
+ Range Read() {
+ return Range(data + head, tail - head);
+ }
+
+ /**
+ * Marks a chunk as consumed.
+ */
+ void Consume(size_type n) {
+ assert(tail <= size);
+ assert(head <= tail);
+ assert(n <= tail);
+ assert(head + n <= tail);
+
+ head += n;
+ }
+};
+
+#endif