mirror of https://github.com/status-im/qzxing.git
73 lines
2.5 KiB
C++
73 lines
2.5 KiB
C++
#ifndef BIGINTEGERUTILS_H
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#define BIGINTEGERUTILS_H
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#include "BigInteger.hh"
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#include <string>
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#include <iostream>
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/* This file provides:
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* - Convenient std::string <-> BigUnsigned/BigInteger conversion routines
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* - std::ostream << operators for BigUnsigned/BigInteger */
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// std::string conversion routines. Base 10 only.
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std::string bigUnsignedToString(const BigUnsigned &x);
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std::string bigIntegerToString(const BigInteger &x);
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BigUnsigned stringToBigUnsigned(const std::string &s);
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BigInteger stringToBigInteger(const std::string &s);
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// Creates a BigInteger from data such as `char's; read below for details.
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template <class T>
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BigInteger dataToBigInteger(const T* data, BigInteger::Index length, BigInteger::Sign sign);
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// Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'.
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std::ostream &operator <<(std::ostream &os, const BigUnsigned &x);
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// Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'.
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// My somewhat arbitrary policy: a negative sign comes before a base indicator (like -0xFF).
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std::ostream &operator <<(std::ostream &os, const BigInteger &x);
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// BEGIN TEMPLATE DEFINITIONS.
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/*
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* Converts binary data to a BigInteger.
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* Pass an array `data', its length, and the desired sign.
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*
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* Elements of `data' may be of any type `T' that has the following
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* two properties (this includes almost all integral types):
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*
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* (1) `sizeof(T)' correctly gives the amount of binary data in one
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* value of `T' and is a factor of `sizeof(Blk)'.
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*
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* (2) When a value of `T' is casted to a `Blk', the low bytes of
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* the result contain the desired binary data.
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*/
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template <class T>
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BigInteger dataToBigInteger(const T* data, BigInteger::Index length, BigInteger::Sign sign) {
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// really ceiling(numBytes / sizeof(BigInteger::Blk))
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unsigned int pieceSizeInBits = 8 * sizeof(T);
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unsigned int piecesPerBlock = sizeof(BigInteger::Blk) / sizeof(T);
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unsigned int numBlocks = (length + piecesPerBlock - 1) / piecesPerBlock;
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// Allocate our block array
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BigInteger::Blk *blocks = new BigInteger::Blk[numBlocks];
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BigInteger::Index blockNum, pieceNum, pieceNumHere;
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// Convert
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for (blockNum = 0, pieceNum = 0; blockNum < numBlocks; blockNum++) {
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BigInteger::Blk curBlock = 0;
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for (pieceNumHere = 0; pieceNumHere < piecesPerBlock && pieceNum < length;
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pieceNumHere++, pieceNum++)
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curBlock |= (BigInteger::Blk(data[pieceNum]) << (pieceSizeInBits * pieceNumHere));
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blocks[blockNum] = curBlock;
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}
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// Create the BigInteger.
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BigInteger x(blocks, numBlocks, sign);
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delete [] blocks;
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return x;
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}
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#endif
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