source: xplcommon/src/xplcommon/Buffer.h@ 30:1dde7e03353f

// Copyright (c) 2012 by István Váradi

// This file is part of libxplcommon, a common utility library for
// development related to X-Plane

// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:

// 1. Redistributions of source code must retain the above copyright notice, this
//    list of conditions and the following disclaimer.
// 2. 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 COPYRIGHT OWNER 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.

// The views and conclusions contained in the software and documentation are those
// of the authors and should not be interpreted as representing official policies,
// either expressed or implied, of the FreeBSD Project.

#ifndef XPLCOMMON_BUFFER_H
#define XPLCOMMON_BUFFER_H
//------------------------------------------------------------------------------

#include <algorithm>

#include <cstdlib>
#include <cstring>

//------------------------------------------------------------------------------

namespace xplcommon {

//------------------------------------------------------------------------------

/**
 * Base class for buffers. It maintains a memory area of a certain
 * capacity and the length of the data in the buffer.
 */
class Buffer
{
private:
    /**
     * The data itself.
     */
    unsigned char* data;

    /**
     * The capacity of the buffer.
     */
    size_t capacity;

    /**
     * The amount of data in the buffer.
     */
    size_t length;

public:
    /**
     * Construct the buffer with the given capacity.
     */
    Buffer(size_t capacity);

    /**
     * Destroy the buffer.
     */
    ~Buffer();

    /**
     * Get the capacity of the buffer.
     */
    size_t getCapacity() const;

    /**
     * Get the pointer to the data.
     */
    const unsigned char* getData() const;

    /**
     * Get the pointer to the data for modification.
     */
    unsigned char* getData();

    /**
     * Get the length of the data.
     */
    size_t getLength() const;

    /**
     * Get whether the buffer is empty or not.
     */
    bool isEmpty() const;

    /**
     * Get the available capacity in the buffer.
     */
    size_t getAvailable() const;

    /**
     * Reset the buffer.
     */
    void reset();

    /**
     * Add the given amount to the length. Should not exceed the
     * capacity!
     *
     * @return the actual amount added.
     */
    size_t addLength(size_t n);

    /**
     * Append the given data to the contents of the given buffer.
     *
     * @return the number of bytes actually appended
     */
    size_t append(const void* src, size_t size);

    /**
     * Extract data into the given buffer from the given offset.
     *
     * @return the number of bytes actually extracted.
     */
    size_t extract(void* dest, size_t size, size_t offset = 0) const;
};

//------------------------------------------------------------------------------
// Inline definitions
//------------------------------------------------------------------------------

inline Buffer::Buffer(size_t capacity) :
    data(new unsigned char[capacity]),
    capacity(capacity),
    length(0)
{
}

//------------------------------------------------------------------------------

inline Buffer::~Buffer()
{
    delete[] data;
}

//------------------------------------------------------------------------------

inline size_t Buffer::getCapacity() const
{
    return capacity;
}

//------------------------------------------------------------------------------

inline const unsigned char* Buffer::getData() const
{
    return data;
}

//------------------------------------------------------------------------------

inline unsigned char* Buffer::getData()
{
    return data;
}

//------------------------------------------------------------------------------

inline size_t Buffer::getLength() const
{
    return length;
}

//------------------------------------------------------------------------------

inline bool Buffer::isEmpty() const
{
    return length==0;
}

//------------------------------------------------------------------------------

inline size_t Buffer::getAvailable() const
{
    return capacity - length;
}

//------------------------------------------------------------------------------

inline void Buffer::reset()
{
    length = 0;
}

//------------------------------------------------------------------------------

inline size_t Buffer::addLength(size_t n)
{
    size_t toAdd = std::min(n, getAvailable());
    length += toAdd;
    return toAdd;
}

//------------------------------------------------------------------------------

inline size_t Buffer::append(const void* src, size_t size)
{
    size_t toCopy = std::min(size, getAvailable());
    memcpy(data + length, src, toCopy);
    length += toCopy;
    return toCopy;
}

//------------------------------------------------------------------------------

inline size_t Buffer::extract(void* dest, size_t size, size_t offset) const
{
    size_t toCopy = (offset>=length) ? 0 : std::min(size, length - offset);
    memcpy(dest, data + offset, toCopy);
    return toCopy;
}

//------------------------------------------------------------------------------

} /* namespace xplcommon */

//------------------------------------------------------------------------------
#endif // XPLCOMMON_BUFFER_H

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