/*
 * ZoneMinder flexible memory class implementation, $Date$, $Revision$
 * Copyright (C) 2003  Philip Coombes
 * 
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
*/ 

#include <string.h>

#include "zm.h"
#include "zm_buffer.h"

unsigned int Buffer::Assign( const unsigned char *p_storage, unsigned int p_size )
{
	delete[] storage;
	size = allocation = p_size;
	head = storage = new unsigned char[size];
	memcpy( storage, p_storage, size );
	tail = head + size;
	return( size );
}

unsigned int Buffer::Expand( unsigned int count )
{
	int spare = allocation - size;
	int head_space = head - storage;
	int tail_space = spare - head_space;
	int width = tail - head;
	if ( spare > count )
	{
		if ( tail_space < count )
		{
			memmove( storage, head, size );
			head = storage;
			tail = head + width;
		}
	}
	else
	{
		allocation += count;
		unsigned char *new_storage = new unsigned char[allocation];
		if ( storage )
		{
			memcpy( new_storage, storage, size );
			delete[] storage;
		}
		storage = new_storage;
		head = storage;
		tail = head + width;
	}
	size += count;
	return( size );
}