source: trunk/src/core/RpSimpleBuffer.cc @ 1038

/*
 * ======================================================================
 *  Rappture::SimpleBuffer
 *
 *  AUTHOR:  Derrick Kearney, Purdue University
 *
 *  Copyright (c) 2004-2008  Purdue Research Foundation
 * ----------------------------------------------------------------------
 *  See the file "license.terms" for information on usage and
 *  redistribution of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 * ======================================================================
 *
 *  This code is based on the Tcl_DString facility included in the
 *  Tcl source release, which includes the following copyright:
 *
 *  Copyright (c) 1987-1993 The Regents of the University of California.
 *  Copyright (c) 1994-1998 Sun Microsystems, Inc.
 *  Copyright (c) 2001 by Kevin B. Kenny.  All rights reserved.
 *
 *  This software is copyrighted by the Regents of the University of
 *  California, Sun Microsystems, Inc., Scriptics Corporation,
 *  and other parties.  The following terms apply to all files associated
 *  with the software unless explicitly disclaimed in individual files.
 *
 *  The authors hereby grant permission to use, copy, modify, distribute,
 *  and license this software and its documentation for any purpose, provided
 *  that existing copyright notices are retained in all copies and that this
 *  notice is included verbatim in any distributions. No written agreement,
 *  license, or royalty fee is required for any of the authorized uses.
 *  Modifications to this software may be copyrighted by their authors
 *  and need not follow the licensing terms described here, provided that
 *  the new terms are clearly indicated on the first page of each file where
 *  they apply.
 *
 *  IN NO EVENT SHALL THE AUTHORS OR DISTRIBUTORS BE LIABLE TO ANY PARTY
 *  FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES
 *  ARISING OUT OF THE USE OF THIS SOFTWARE, ITS DOCUMENTATION, OR ANY
 *  DERIVATIVES THEREOF, EVEN IF THE AUTHORS HAVE BEEN ADVISED OF THE
 *  POSSIBILITY OF SUCH DAMAGE.
 *
 *  THE AUTHORS AND DISTRIBUTORS SPECIFICALLY DISCLAIM ANY WARRANTIES,
 *  INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY,
 *  FITNESS FOR A PARTICULAR PURPOSE, AND NON-INFRINGEMENT.  THIS SOFTWARE
 *  IS PROVIDED ON AN "AS IS" BASIS, AND THE AUTHORS AND DISTRIBUTORS HAVE
 *  NO OBLIGATION TO PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
 *  MODIFICATIONS.
 *
 *  GOVERNMENT USE: If you are acquiring this software on behalf of the
 *  U.S. government, the Government shall have only "Restricted Rights"
 *  in the software and related documentation as defined in the Federal·
 *  Acquisition Regulations (FARs) in Clause 52.227.19 (c) (2).  If you
 *  are acquiring the software on behalf of the Department of Defense, the
 *  software shall be classified as "Commercial Computer Software" and the
 *  Government shall have only "Restricted Rights" as defined in Clause
 *  252.227-7013 (c) (1) of DFARs.  Notwithstanding the foregoing, the
 *  authors grant the U.S. Government and others acting in its behalf
 *  permission to use and distribute the software in accordance with the
 *  terms specified in this license.·
 *
 * ======================================================================
 */

#include "RpSimpleBuffer.h"

#ifdef __cplusplus
    extern "C" {
#endif // ifdef __cplusplus

using namespace Rappture;

/**
 * Construct an empty SimpleBuffer.
 */
SimpleBuffer::SimpleBuffer()
{
    bufferInit();
}


/**
 * Construct an empty SimpleBuffer of specified size.
 */
SimpleBuffer::SimpleBuffer(int nbytes)
{
    char* newBuffer = NULL;

    bufferInit();

    if (nbytes == 0) {
        // ignore requests for sizes equal to zero
        return;
    } else if (nbytes < 0) {
        // sizes less than zero are set to min_size
        nbytes = RP_SIMPLEBUFFER_MIN_SIZE;
    } else {
        // keep nbytes at requested size
    }

    newBuffer = new char[nbytes];
    if (newBuffer == NULL) {
        // memory error
        _fileState = false;
    } else {
        _spaceAvl = nbytes;
        _size = nbytes;
        _buf = newBuffer;
    }
}


/**
 * Construct a SimpleBuffer loaded with initial data.
 *
 * @param bytes pointer to bytes being stored.
 * @param nbytes number of bytes being stored.
 */
SimpleBuffer::SimpleBuffer(const char* bytes, int nbytes)
{
    bufferInit();
    append(bytes,nbytes);
}


/**
 * Copy constructor
 * @param SimpleBuffer object to copy
 */
SimpleBuffer::SimpleBuffer(const SimpleBuffer& b)
{
    bufferInit();
    append(b.bytes(),b.size());
}


/**
 * Assignment operator
 * @param SimpleBuffer object to copy
 */
SimpleBuffer&
SimpleBuffer::operator=(const SimpleBuffer& b)
{
    bufferFree();
    bufferInit();
    append(b.bytes(),b.size());
    return *this;
}


/**
 * Operator +
 * @param SimpleBuffer object to add
 */
SimpleBuffer
SimpleBuffer::operator+(const SimpleBuffer& b) const
{
    SimpleBuffer newBuffer(*this);
    newBuffer.operator+=(b);
    return newBuffer;
}


/**
 * Operator +=
 * @param SimpleBuffer object to add
 */
SimpleBuffer&
SimpleBuffer::operator+=(const SimpleBuffer& b)
{
    append(b.bytes(),b.size());
    return *this;
}


/**
 * Destructor
 */
SimpleBuffer::~SimpleBuffer()
{
    bufferFree();
}


/**
 * Get the bytes currently stored in the buffer.  These bytes can
 * be stored, and used later to construct another Buffer to
 * decode the information.
 *
 * @return Pointer to the bytes in the buffer.
 */
const char*
SimpleBuffer::bytes() const
{
    return _buf;
}


/**
 * Get the number of bytes currently stored in the buffer.
 * @return Number of the bytes used in the buffer.
 */
unsigned int
SimpleBuffer::size() const
{
    return _size;
}


/**
 * Clear the buffer, making it empty.
 * @return Reference to this buffer.
 */
SimpleBuffer&
SimpleBuffer::clear()
{
    bufferFree();
    bufferInit();

    return *this;
}


/**
 * Append bytes to the end of this buffer
 * @param Buffer object to copy
 * @return Reference to this buffer.
 */
int
SimpleBuffer::append(const char* bytes, int nbytes)
{
    unsigned int newSize = 0;
    char *newBuffer = NULL;

    // User specified NULL buffer to append
    if ( (bytes == NULL) && (nbytes < 1) ) {
        return 0;
    }

    if (nbytes == -1) {
        // user signaled null terminated string
        nbytes = strlen(bytes);
    }

    if (nbytes <= 0) {
        // no data written, invalid option
        return nbytes;
    }

    // Empty internal buffer, make sure its properly initialized.
    if (_buf == NULL) {
        bufferInit();
    }

    newSize = (unsigned int)(_size + nbytes);

    // ensure that our smallest buffer is RP_SIMPLEBUFFER_MIN_SIZE bytes
    if (newSize < (RP_SIMPLEBUFFER_MIN_SIZE/2)) {
        newSize = (RP_SIMPLEBUFFER_MIN_SIZE/2);
    }

    /*
     * Allocate a larger buffer for the string if the current one isn't
     * large enough. Allocate extra space in the new buffer so that there
     * will be room to grow before we have to allocate again.
     */

    if (newSize >= _spaceAvl) {
        _spaceAvl = newSize * 2;
        newBuffer = new char[_spaceAvl];
        if (newBuffer == NULL) {
            // return memory error
            return -1;
        }
        if (_buf != NULL) {
            memcpy((void*) newBuffer, (void*) _buf, (size_t) _size);
            delete [] _buf;
            _buf = NULL;
        }
        _buf = newBuffer;
    }

    memcpy((void*) (_buf + _size), (void*) bytes, (size_t) nbytes);

    _size = _size + (unsigned int) nbytes;

    return nbytes;
}


/**
 * Read data from the buffer into a memory location provided by caller
 * @param Pointer locating where to place read bytes.
 * @param Size of the memory location.
 * @return Number of bytes written to memory location
 */
int
SimpleBuffer::read(const char* bytes, int nbytes)
{
    unsigned int bytesRead = 0;

    // SimpleBuffer is empty.
    if (_buf == NULL) {
        return 0;
    }

    // User specified NULL buffer.
    if (bytes == NULL) {
        return 0;
    }

    // User specified negative buffer size
    if (nbytes <= 0) {
        return 0;
    }

    // make sure we don't read off the end of our buffer
    if ( (_pos + nbytes) >= _size ) {
        bytesRead = (_size - _pos);
    }
    else {
        bytesRead = (unsigned int) nbytes;
    }

    if (bytesRead <= 0) {
        return 0;
    }

    if (bytesRead > 0) {
        memcpy((void*) bytes, (void*) (_buf+_pos), (size_t) bytesRead);
    }

    _pos = (_pos + bytesRead);

    return (int)bytesRead;
}


/**
 * Set buffer position indicator to spot within the buffer
 * @param Offset from whence location in buffer.
 * @param Place from where offset is added or subtracted.
 * @return 0 on success, anything else is failure
 */
int
SimpleBuffer::seek(int offset, int whence)
{
    int retVal = 0;

    if (_buf == NULL) {
        return -1 ;
    }

    if (whence == SEEK_SET) {
        if (offset < 0) {
            /* dont go off the beginning of data */
            _pos = 0;
        }
        else if (offset >= (int)_size) {
            /* dont go off the end of data */
            _pos = _size - 1;
        }
        else {
            _pos = (unsigned int)(_pos + offset);
        }
    }
    else if (whence == SEEK_CUR) {
        if ( (_pos + offset) < 0) {
            /* dont go off the beginning of data */
            _pos = 0;
        }
        else if ((_pos + offset) >= _size) {
            /* dont go off the end of data */
            _pos = _size - 1;
        }
        else {
            _pos = (unsigned int)(_pos + offset);
        }
    }
    else if (whence == SEEK_END) {
        if (offset <= (-1*((int)_size))) {
            /* dont go off the beginning of data */
            _pos = 0;
        }
        else if (offset >= 0) {
            /* dont go off the end of data */
            _pos = _size - 1;
        }
        else {
            _pos = (unsigned int)((_size - 1) + offset);
        }
    }
    else {
        retVal = -1;
    }

    return retVal;
}


/**
 * Tell caller the offset of the position indicator from the start of buffer
 * @return Number of bytes the position indicator is from start of buffer
 */
int
SimpleBuffer::tell() const
{
   return (int)_pos;
}


/**
 * Read data from the buffer into a memory location provided by caller
 */
SimpleBuffer&
SimpleBuffer::rewind()
{
    _pos = 0;
    return *this;
}


/**
 * Tell if the last file like operation (ie. read()) was successful
 * or if there was a failure like eof, or bad memory
 * @return True or false boolean value
 */
bool
SimpleBuffer::good() const
{
    return (_fileState);
}


/**
 * Tell if the last file like operation (ie. read()) failed
 * Opposite of good()
 * @return True or false boolean value
 */
bool
SimpleBuffer::bad() const
{
    return (!_fileState);
}


/**
 * Tell if the position flag is at the end of the buffer
 * @return True or false boolean value
 */
bool
SimpleBuffer::eof() const
{
    return (_pos >= _size);
}


/**
 * Move the data from this SimpleBuffer to the SimpleBuffer provided by
 * the caller. All data except the _pos is moved and this SimpleBuffer is
 * re-initialized with bufferInit().
 * @param SimpleBuffer to move the information to
 * @return reference to this SimpleBuffer object.
 */
SimpleBuffer&
SimpleBuffer::move(SimpleBuffer& b)
{
    bufferFree();

    _buf = b._buf;
    _pos = b._pos;
    _size = b._size;
    _spaceAvl = b._spaceAvl;
    _fileState = b._fileState;

    b.bufferInit();

    return *this;
}


 /**
  *  Initializes a dynamic buffer, discarding any previous contents
  *  of the buffer. bufferFree() should have been called already
  *  if the dynamic buffer was previously in use.
  */
void
SimpleBuffer::bufferInit()
{
    _buf = NULL;
    _pos = 0;
    _size = 0;
    _spaceAvl = 0;
    _fileState = true;
}


/**
 *  Frees up any memory allocated for the dynamic buffer and
 *  reinitializes the buffer to an empty state.
 */
void
SimpleBuffer::bufferFree()
{
    if (_buf != NULL) {
        delete [] _buf;
        _buf = NULL;
    }
    bufferInit();
}



#ifdef __cplusplus
    }
#endif // ifdef __cplusplus