X-Git-Url: https://mattmccutchen.net/bigint/bigint.git/blobdiff_plain/05780f4b578d6ae054be0b19b8498d32a4f16c60..refs/heads/no-explicit-template-args:/BigIntegerUtils.hh

diff --git a/BigIntegerUtils.hh b/BigIntegerUtils.hh
index 0080942..2f6d22f 100644
--- a/BigIntegerUtils.hh
+++ b/BigIntegerUtils.hh
@@ -1,26 +1,23 @@
-/*
-* Matt McCutchen's Big Integer Library
-* http://mysite.verizon.net/mccutchen/bigint/
-*/
-
-#ifndef BIGINTEGERUTILS
-#define BIGINTEGERUTILS
+#ifndef BIGINTEGERUTILS_H
+#define BIGINTEGERUTILS_H
 
 #include "BigInteger.hh"
 #include <string>
 #include <iostream>
 
-/*
-* This file includes:
-* (1) `std::string <=> BigUnsigned/BigInteger' conversion routines easier than `BigUnsignedInABase'
-* (2) << and >> operators for BigUnsigned/BigInteger, std::istream/std::ostream
-*/
+/* This file provides:
+ * - Convenient std::string <-> BigUnsigned/BigInteger conversion routines
+ * - std::ostream << operators for BigUnsigned/BigInteger */
 
-// Conversion routines.  Base 10 only.
-std::string easyBUtoString(const BigUnsigned &x);
-std::string easyBItoString(const BigInteger &x);
-BigUnsigned easyStringToBU(const std::string &s);
-BigInteger easyStringToBI(const std::string &s);
+// 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);
@@ -29,4 +26,47 @@ std::ostream &operator <<(std::ostream &os, const BigUnsigned &x);
 // 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