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/*
* substream.cpp
* substream class implementation
* Copyright (C) 2005 Christopher Han <xiphux@gmail.com>
*
* This file is part of hpiutil2.
*
* hpiutil2 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.
*
* hpiutil2 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 hpiutil2; if not, write to the Free Software
* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdlib.h>
#include "substream.h"
/**
* Constructor
* @param sf scrambledfile to read from
* @param off offset in scrambledfile to start from
* @param len length of substream data
*/
hpiutil::substream::substream(scrambledfile &sf, const boost::uint32_t off, const boost::uint32_t len)
{
data = (boost::uint8_t*)calloc(len,sizeof(boost::uint8_t));
sf.read(data,off,len);
position = 0;
length = len;
}
/**
* Destructor
*/
hpiutil::substream::~substream()
{
free((void*)data);
}
/**
* read
* reads a single byte
* @return byte read
*/
boost::uint8_t hpiutil::substream::read()
{
if (position >= length)
return 0;
return data[position++];
}
/**
* read
* reads data into a buffer
* @return the number of bytes read
* @param buf buffer to read into
*/
boost::uint32_t hpiutil::substream::read(boost::uint8_t *buf)
{
if (position >= length)
return 0;
boost::uint32_t oldpos = position;
boost::uint32_t len = bitmin(sizeof(buf),(length-position));
for (boost::uint32_t j = 0; j < len; j++)
buf[j] = data[position++];
return position - oldpos;
}
/**
* read
* reads data into a buffer
* @return the number of bytes read
* @param buf buffer to read into
* @param off offset in substream to start reading from
* @param len size of data to read
*/
boost::uint32_t hpiutil::substream::read(boost::uint8_t *buf, const boost::uint32_t off, const boost::uint32_t len)
{
position = bitmin(off,length);
if (position >= length)
return 0;
boost::uint32_t reallen = bitmin(len,(length-position));
for (boost::uint32_t j = 0; j < reallen; j++)
buf[j] = data[position++];
return position-off;
}
/**
* checksum
* performs a checksum on the substream data by
* adding up all bytes.
* @return checksum
* @param start byte to start with
*/
boost::uint32_t hpiutil::substream::checksum(const boost::uint32_t start)
{
boost::uint32_t check = 0;
for (boost::uint32_t i = start; i < length; i++)
check += data[i];
return check;
}
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