binary_i_memory_block.cpp

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/** @file
 *  @author Bram de Greve (bram@cocamware.com)
 *  @author Tom De Muer (tom@cocamware.com)
 *
 *  *** BEGIN LICENSE INFORMATION ***
 *  
 *  The contents of this file are subject to the Common Public Attribution License 
 *  Version 1.0 (the "License"); you may not use this file except in compliance with 
 *  the License. You may obtain a copy of the License at 
 *  http://lass.sourceforge.net/cpal-license. The License is based on the 
 *  Mozilla Public License Version 1.1 but Sections 14 and 15 have been added to cover 
 *  use of software over a computer network and provide for limited attribution for 
 *  the Original Developer. In addition, Exhibit A has been modified to be consistent 
 *  with Exhibit B.
 *  
 *  Software distributed under the License is distributed on an "AS IS" basis, WITHOUT 
 *  WARRANTY OF ANY KIND, either express or implied. See the License for the specific 
 *  language governing rights and limitations under the License.
 *  
 *  The Original Code is LASS - Library of Assembled Shared Sources.
 *  
 *  The Initial Developer of the Original Code is Bram de Greve and Tom De Muer.
 *  The Original Developer is the Initial Developer.
 *  
 *  All portions of the code written by the Initial Developer are:
 *  Copyright (C) 2004-2011 the Initial Developer.
 *  All Rights Reserved.
 *  
 *  Contributor(s):
 *
 *  Alternatively, the contents of this file may be used under the terms of the 
 *  GNU General Public License Version 2 or later (the GPL), in which case the 
 *  provisions of GPL are applicable instead of those above.  If you wish to allow use
 *  of your version of this file only under the terms of the GPL and not to allow 
 *  others to use your version of this file under the CPAL, indicate your decision by 
 *  deleting the provisions above and replace them with the notice and other 
 *  provisions required by the GPL License. If you do not delete the provisions above,
 *  a recipient may use your version of this file under either the CPAL or the GPL.
 *  
 *  *** END LICENSE INFORMATION ***
 */
 
#include "lass_common.h"
#include "binary_i_memory_block.h"
#include <string.h>
 
namespace lass
{
 
namespace io
{
 
/** Construct an "empty" closed stream..
 */
BinaryIMemoryBlock::BinaryIMemoryBlock():
    BinaryIStream(),
    begin_(0),
    size_(0),
    position_(0)
{
}
 
 
 
/** Construct stream by pointer to memory block and length of block
 */
BinaryIMemoryBlock::BinaryIMemoryBlock( const void* begin, pos_type size ):
    BinaryIStream(),
    begin_(static_cast<const TByte*>(begin)),
    size_(size),
    position_(0)
{
}
 
 
 
/** Construct stream by pointer to memory block and to one byte past end of block.
 */
BinaryIMemoryBlock::BinaryIMemoryBlock( const void* begin, const void* end ):
    BinaryIStream(),
    begin_(static_cast<const TByte*>(begin)),
    size_(0),
    position_(0)
{
    off_type size = static_cast<const TByte*>(end) - static_cast<const TByte*>(begin);
    if (size >= 0)
    {
        size_ = static_cast<pos_type>(size);
    }
    else
    {
        setstate(std::ios_base::badbit);
    }
}
 
 
 
// --- private -------------------------------------------------------------------------------------
 
size_t BinaryIMemoryBlock::doRead(void* out, size_t numberOfBytes)
{
    if (!begin_)
    {
        setstate(std::ios_base::badbit);
        return 0;
    }
    if (!good())
    {
        return 0;
    }
    if (position_ >= size_)
    {
        setstate(std::ios_base::eofbit);
        return 0;
    }
    pos_type next = position_ + numberOfBytes;
    if (next > size_ || next < position_)
    {
        next = size_;
        numberOfBytes = size_ - position_;
    }
    memcpy(out, &begin_[position_], numberOfBytes);
    position_ = next;
    return numberOfBytes;
}
 
 
 
BinaryIMemoryBlock::pos_type BinaryIMemoryBlock::doTellg() const
{
    return position_;
}
 
 
 
void BinaryIMemoryBlock::doSeekg(pos_type position)
{
    LASS_ASSERT(good());
    position_ = position;
}
 
 
 
void BinaryIMemoryBlock::doSeekg(off_type offset, std::ios_base::seekdir direction)
{
    LASS_ASSERT(good());
 
    auto seek = [this](pos_type current, off_type offset)
    {
        if (offset < 0)
        {
            const pos_type negoffset = static_cast<pos_type>(-offset);
            if (negoffset > current)
            {
                setstate(std::ios_base::failbit);
                return;
            }
            this->position_ = current - negoffset;
        }
        else
        {
            const pos_type posoffset = static_cast<pos_type>(offset);
            if (current > num::NumTraits<pos_type>::max - posoffset)
            {
                setstate(std::ios_base::failbit);
                return;
            }
            this->position_ = current + posoffset;
        }
    };
 
    switch (direction)
    {
    case std::ios_base::beg:
        if (offset < 0)
        {
            setstate(std::ios_base::failbit);
            return;
        }
        position_ = static_cast<pos_type>(offset);
        break;
    case std::ios_base::cur:
        seek(position_, offset);
        break;
    case std::ios_base::end:
        seek(size_, offset);
        break;
    default:
        LASS_ASSERT(false);
    };
}
 
}
 
}