Buffer.h

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/*
 * Copyright (c) 2005 Palmsource, Inc.
 * 
 * This software is licensed as described in the file LICENSE, which
 * you should have received as part of this distribution. The terms
 * are also available at http://www.openbinder.org/license.html.
 * 
 * This software consists of voluntary contributions made by many
 * individuals. For the exact contribution history, see the revision
 * history and logs, available at http://www.openbinder.org
 */

#ifndef _SUPPORT_BUFFER_H_
#define _SUPPORT_BUFFER_H_

#include <support/SupportDefs.h>
#include <string.h>

#if _SUPPORTS_NAMESPACE
namespace palmos {
namespace support {
#endif

class SBuffer
{
    public: // members
        SBuffer *               next;   // next buffer in the chain, or NULL

    public: // methods
        inline                  SBuffer();
        inline                  SBuffer(void * data, size_t size);
        inline                  SBuffer(const SBuffer& clone);
        inline  SBuffer&        operator=(const SBuffer& clone);

        inline  void            MakeEmpty();
        inline  status_t        SetTo(void * data, size_t size);

        inline  bool            IsValid() const;

        // access just this buffer in the chain
        inline  void const *    Data() const;
        inline  void *          WriteData() const;
        inline  size_t          Size() const;

        // access entire chain starting with this buffer
        size_t          ChainSize() const
        {
            size_t s = 0;
            for (SBuffer const * i = this; i != 0; i = i->next)
            {
                s += i->Size();
            }
            return s;
        }
        
        // copy data out of the chain starting with this buffer
        ssize_t         CopyTo(void * dest, size_t size, size_t fromOffset) const
        {
            if (dest == 0) return B_BAD_VALUE;
            ssize_t total = 0;
            SBuffer const * i = this;
            while (size && i)
            {
                if (fromOffset >= i->Size())
                {
                    fromOffset -= i->Size();
                    i = i->next;
                    continue;
                }
                size_t toCopy = i->Size() - fromOffset;
                if (toCopy > size)
                {
                    toCopy = size;
                }
                memcpy(dest, (int8_t*)i->Data() + fromOffset, toCopy);
                size -= toCopy;
                total += toCopy;
                if (size)
                {
                    fromOffset = 0;
                    dest = (int8_t*)dest + toCopy;
                    i = i->next;
                }
            }
            return total;
        }
        
    protected:
                size_t          m_size;
                void *          m_data;
};

inline
SBuffer::SBuffer()
    : next(0), m_size(0), m_data(0)
{
}

inline
SBuffer::SBuffer(void * data, size_t size)
    : next(0), m_size(size), m_data(data)
{
}

inline
SBuffer::SBuffer(const SBuffer& clone)
{
    next = clone.next;
    m_size = clone.m_size;
    m_data = clone.m_data;
}

inline SBuffer&
SBuffer::operator=(const SBuffer& clone)
{
    next = clone.next;
    m_size = clone.m_size;
    m_data = clone.m_data;
    return *this;
}

inline void
SBuffer::MakeEmpty()
{
    next = 0;
    m_size = 0;
    m_data = 0;
}

inline status_t
SBuffer::SetTo(void * data, size_t size)
{
    m_size = size;
    m_data = data;
    return B_OK;
}

inline bool
SBuffer::IsValid() const
{
    return (m_data != 0);
}

inline void const *
SBuffer::Data() const
{
    return m_data;
}

inline void *
SBuffer::WriteData() const
{
    return m_data;
}

inline size_t
SBuffer::Size() const
{
    return m_size;
}

#if _SUPPORTS_NAMESPACE
} } // palmos::support
#endif

#endif // _SUPPORT_BUFFER_H_

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PalmSource, Inc. © 2005