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#ifndef BIGINTEGERUTILS_H
#define BIGINTEGERUTILS_H
#include "BigInteger.h"
#include <string>
#include <iostream>
/* This file provides:
* - Convenient std::string <-> BigUnsigned/BigInteger conversion routines
* - std::ostream << operators for BigUnsigned/BigInteger */
// std::string conversion routines. Base 10 only.
std::string bigUnsignedToString(const BigUnsigned &x);
std::string bigIntegerToString(const BigInteger &x);
BigUnsigned stringToBigUnsigned(const std::string &s);
BigInteger stringToBigInteger(const std::string &s);
// Creates a BigInteger from data such as `char's; read below for details.
template <class T>
BigInteger dataToBigInteger(const T* data, BigInteger::Index length, BigInteger::Sign sign);
// Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'.
std::ostream &operator <<(std::ostream &os, const BigUnsigned &x);
// Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'.
// My somewhat arbitrary policy: a negative sign comes before a base indicator (like -0xFF).
std::ostream &operator <<(std::ostream &os, const BigInteger &x);
// BEGIN TEMPLATE DEFINITIONS.
/*
* Converts binary data to a BigInteger.
* Pass an array `data', its length, and the desired sign.
*
* Elements of `data' may be of any type `T' that has the following
* two properties (this includes almost all integral types):
*
* (1) `sizeof(T)' correctly gives the amount of binary data in one
* value of `T' and is a factor of `sizeof(Blk)'.
*
* (2) When a value of `T' is casted to a `Blk', the low bytes of
* the result contain the desired binary data.
*/
template <class T>
BigInteger dataToBigInteger(const T* data, BigInteger::Index length, BigInteger::Sign sign) {
// really ceiling(numBytes / sizeof(BigInteger::Blk))
unsigned int pieceSizeInBits = 8 * sizeof(T);
unsigned int piecesPerBlock = sizeof(BigInteger::Blk) / sizeof(T);
unsigned int numBlocks = (length + piecesPerBlock - 1) / piecesPerBlock;
// Allocate our block array
BigInteger::Blk *blocks = new BigInteger::Blk[numBlocks];
BigInteger::Index blockNum, pieceNum, pieceNumHere;
// Convert
for (blockNum = 0, pieceNum = 0; blockNum < numBlocks; blockNum++) {
BigInteger::Blk curBlock = 0;
for (pieceNumHere = 0; pieceNumHere < piecesPerBlock && pieceNum < length;
pieceNumHere++, pieceNum++)
curBlock |= (BigInteger::Blk(data[pieceNum]) << (pieceSizeInBits * pieceNumHere));
blocks[blockNum] = curBlock;
}
// Create the BigInteger.
BigInteger x(blocks, numBlocks, sign);
delete blocks;
return x;
}
#endif
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Shao Voon is from Singapore. His interest lies primarily in computer graphics, software optimization, concurrency, security, and Agile methodologies.
In recent years, he shifted focus to software safety research. His hobby is writing a free C++ DirectX photo slideshow application which can be viewed
here.