2014-07-23 13:03:52 +00:00
|
|
|
// Copyright (c) 2014, The Monero Project
|
|
|
|
//
|
|
|
|
// All rights reserved.
|
|
|
|
//
|
|
|
|
// Redistribution and use in source and binary forms, with or without modification, are
|
|
|
|
// permitted provided that the following conditions are met:
|
|
|
|
//
|
|
|
|
// 1. Redistributions of source code must retain the above copyright notice, this list of
|
|
|
|
// conditions and the following disclaimer.
|
|
|
|
//
|
|
|
|
// 2. Redistributions in binary form must reproduce the above copyright notice, this list
|
|
|
|
// of conditions and the following disclaimer in the documentation and/or other
|
|
|
|
// materials provided with the distribution.
|
|
|
|
//
|
|
|
|
// 3. Neither the name of the copyright holder nor the names of its contributors may be
|
|
|
|
// used to endorse or promote products derived from this software without specific
|
|
|
|
// prior written permission.
|
|
|
|
//
|
|
|
|
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
|
|
|
|
// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
|
|
|
|
// MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
|
|
|
|
// THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
|
|
|
|
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
|
|
// PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
|
|
|
|
// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
|
|
|
|
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
|
|
|
|
// THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
|
|
//
|
|
|
|
// Parts of this file are originally copyright (c) 2012-2013 The Cryptonote developers
|
2014-03-03 22:07:58 +00:00
|
|
|
|
|
|
|
#pragma once
|
|
|
|
|
|
|
|
#include <limits>
|
|
|
|
#include <type_traits>
|
|
|
|
#include <utility>
|
|
|
|
#include <sstream>
|
|
|
|
#include <string>
|
2014-09-11 14:14:05 +00:00
|
|
|
/*! \file varint.h
|
|
|
|
* \breif provides the implementation of varint's
|
|
|
|
*
|
|
|
|
* The representation of varints is rather odd. The first bit of each
|
|
|
|
* octet is significant, it represents wheter there is another part
|
|
|
|
* waiting to be read. For example 0x8002 would return 0x200, even
|
|
|
|
* though 0x02 does not have its msb set. The actual way they are read
|
|
|
|
* is as follows: Strip the msb of each byte, then from left to right,
|
|
|
|
* read in what remains, placing it in reverse, into the buffer. Thus,
|
|
|
|
* the following bit stream: 0xff02 would return 0x027f. 0xff turns
|
|
|
|
* into 0x7f, is placed on the beggining of the buffer, then 0x02 is
|
|
|
|
* unchanged, since its msb is not set, and placed at the end of the
|
|
|
|
* buffer.
|
|
|
|
*/
|
2014-03-03 22:07:58 +00:00
|
|
|
|
|
|
|
namespace tools {
|
|
|
|
|
2014-09-11 14:14:05 +00:00
|
|
|
/*! \breif Error codes for varint
|
|
|
|
*/
|
|
|
|
enum {
|
|
|
|
/* \breif Represents the overflow error */
|
|
|
|
EVARINT_OVERFLOW = -1,
|
|
|
|
/* \breif Represents a non conical represnetation */
|
|
|
|
EVARINT_REPRESENT = -2,
|
|
|
|
};
|
|
|
|
|
|
|
|
/*! \breif writes a varint to a stream.
|
|
|
|
*/
|
|
|
|
template<typename OutputIt, typename T>
|
|
|
|
/* Requires T to be both an integral type and unsigned, should be a compile error if it is not */
|
|
|
|
typename std::enable_if<std::is_integral<T>::value && std::is_unsigned<T>::value, void>::type
|
|
|
|
write_varint(OutputIt &&dest, T i) {
|
|
|
|
/* Make sure that there is one after this */
|
|
|
|
while (i >= 0x80) {
|
|
|
|
*dest = (static_cast<char>(i) & 0x7f) | 0x80;
|
|
|
|
++dest;
|
|
|
|
i >>= 7; /* I should be in multiples of 7, this should just get the next part */
|
2014-03-03 22:07:58 +00:00
|
|
|
}
|
2014-09-11 14:14:05 +00:00
|
|
|
/* writes the last one to dest */
|
|
|
|
*dest = static_cast<char>(i);
|
|
|
|
dest++; /* Seems kinda pointless... */
|
|
|
|
}
|
2014-03-03 22:07:58 +00:00
|
|
|
|
2014-09-11 14:14:05 +00:00
|
|
|
/*! \breif Returns the string that represents the varint
|
|
|
|
*/
|
|
|
|
template<typename T>
|
|
|
|
std::string get_varint_data(const T& v)
|
2014-03-03 22:07:58 +00:00
|
|
|
{
|
|
|
|
std::stringstream ss;
|
|
|
|
write_varint(std::ostreambuf_iterator<char>(ss), v);
|
|
|
|
return ss.str();
|
|
|
|
}
|
2014-09-11 14:14:05 +00:00
|
|
|
/*! \breif reads in the varint as pointer to by InputIt into i
|
|
|
|
*/
|
|
|
|
template<int bits, typename InputIt, typename T>
|
2014-03-03 22:07:58 +00:00
|
|
|
typename std::enable_if<std::is_integral<T>::value && std::is_unsigned<T>::value && 0 <= bits && bits <= std::numeric_limits<T>::digits, int>::type
|
2014-09-11 14:14:05 +00:00
|
|
|
read_varint(InputIt &&first, InputIt &&last, T &write) {
|
|
|
|
int read = 0;
|
|
|
|
write = 0;
|
|
|
|
for (int shift = 0;; shift += 7) {
|
|
|
|
if (first == last) {
|
|
|
|
return read;
|
|
|
|
}
|
|
|
|
unsigned char byte = *first;
|
|
|
|
++first;
|
|
|
|
++read;
|
|
|
|
if (shift + 7 >= bits && byte >= 1 << (bits - shift)) {
|
|
|
|
return EVARINT_OVERFLOW;
|
|
|
|
}
|
|
|
|
if (byte == 0 && shift != 0) {
|
|
|
|
return EVARINT_REPRESENT;
|
|
|
|
}
|
|
|
|
|
|
|
|
write |= static_cast<T>(byte & 0x7f) << shift; /* Does the actualy placing into write, stripping the first bit */
|
|
|
|
|
|
|
|
/* If there is no next */
|
|
|
|
if ((byte & 0x80) == 0) {
|
|
|
|
break;
|
|
|
|
}
|
2014-03-03 22:07:58 +00:00
|
|
|
}
|
2014-09-11 14:14:05 +00:00
|
|
|
return read;
|
|
|
|
}
|
2014-03-03 22:07:58 +00:00
|
|
|
|
2014-09-11 14:14:05 +00:00
|
|
|
/*! \breif Wrapper around the other read_varint,
|
|
|
|
* Sets template parameters for you.
|
|
|
|
*/
|
|
|
|
template<typename InputIt, typename T>
|
2014-03-03 22:07:58 +00:00
|
|
|
int read_varint(InputIt &&first, InputIt &&last, T &i) {
|
2014-09-11 14:14:05 +00:00
|
|
|
return read_varint<std::numeric_limits<T>::digits, InputIt, T>(std::move(first), std::move(last), i);
|
|
|
|
}
|
2014-03-03 22:07:58 +00:00
|
|
|
}
|