1 // Copyright 2014 PDFium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 // Original code by Matt McCutchen, see the LICENSE file. 6 7 #ifndef BIGINTEGERUTILS_H 8 #define BIGINTEGERUTILS_H 9 10 #include "BigInteger.hh" 11 #include <string> 12 #include <ostream> 13 14 /* This file provides: 15 * - Convenient std::string <-> BigUnsigned/BigInteger conversion routines 16 * - std::ostream << operators for BigUnsigned/BigInteger */ 17 18 // std::string conversion routines. Base 10 only. 19 std::string bigUnsignedToString(const BigUnsigned &x); 20 std::string bigIntegerToString(const BigInteger &x); 21 BigUnsigned stringToBigUnsigned(const std::string &s); 22 BigInteger stringToBigInteger(const std::string &s); 23 24 // Creates a BigInteger from data such as `char's; read below for details. 25 template <class T> 26 BigInteger dataToBigInteger(const T* data, BigInteger::Index length, BigInteger::Sign sign); 27 28 // Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'. 29 std::ostream &operator <<(std::ostream &os, const BigUnsigned &x); 30 31 // Outputs x to os, obeying the flags `dec', `hex', `bin', and `showbase'. 32 // My somewhat arbitrary policy: a negative sign comes before a base indicator (like -0xFF). 33 std::ostream &operator <<(std::ostream &os, const BigInteger &x); 34 35 // BEGIN TEMPLATE DEFINITIONS. 36 37 /* 38 * Converts binary data to a BigInteger. 39 * Pass an array `data', its length, and the desired sign. 40 * 41 * Elements of `data' may be of any type `T' that has the following 42 * two properties (this includes almost all integral types): 43 * 44 * (1) `sizeof(T)' correctly gives the amount of binary data in one 45 * value of `T' and is a factor of `sizeof(Blk)'. 46 * 47 * (2) When a value of `T' is casted to a `Blk', the low bytes of 48 * the result contain the desired binary data. 49 */ 50 template <class T> 51 BigInteger dataToBigInteger(const T* data, BigInteger::Index length, BigInteger::Sign sign) { 52 // really ceiling(numBytes / sizeof(BigInteger::Blk)) 53 unsigned int pieceSizeInBits = 8 * sizeof(T); 54 unsigned int piecesPerBlock = sizeof(BigInteger::Blk) / sizeof(T); 55 unsigned int numBlocks = (length + piecesPerBlock - 1) / piecesPerBlock; 56 57 // Allocate our block array 58 BigInteger::Blk *blocks = new BigInteger::Blk[numBlocks]; 59 60 BigInteger::Index blockNum, pieceNum, pieceNumHere; 61 62 // Convert 63 for (blockNum = 0, pieceNum = 0; blockNum < numBlocks; blockNum++) { 64 BigInteger::Blk curBlock = 0; 65 for (pieceNumHere = 0; pieceNumHere < piecesPerBlock && pieceNum < length; 66 pieceNumHere++, pieceNum++) 67 curBlock |= (BigInteger::Blk(data[pieceNum]) << (pieceSizeInBits * pieceNumHere)); 68 blocks[blockNum] = curBlock; 69 } 70 71 // Create the BigInteger. 72 BigInteger x(blocks, numBlocks, sign); 73 74 delete [] blocks; 75 return x; 76 } 77 78 #endif 79
