X-Git-Url: https://mattmccutchen.net/bigint/bigint.git/blobdiff_plain/a8b42b686243a175ea328c74609c7de6a0163274..5ff40cf5d6e822051da902b041ae7ae8f545123e:/BigUnsigned.hh diff --git a/BigUnsigned.hh b/BigUnsigned.hh index 2a55625..50fca2f 100644 --- a/BigUnsigned.hh +++ b/BigUnsigned.hh @@ -1,6 +1,5 @@ /* * Matt McCutchen's Big Integer Library -* http://mysite.verizon.net/mccutchen/bigint/ */ #ifndef BIGUNSIGNED @@ -27,14 +26,14 @@ */ class BigUnsigned : protected NumberlikeArray { - + // TYPES & CONSTANTS public: enum CmpRes { less = -1, equal = 0, greater = 1 }; // Enumeration for the result of a comparison typedef unsigned long Blk; // The number block type that BigUnsigneds are built from typedef NumberlikeArray::Index Index; // (NlA) Type for the index of a block in the array NumberlikeArray::N; // Number of bits in a Blk - + /* // FIELDS protected: @@ -42,34 +41,34 @@ class BigUnsigned : protected NumberlikeArray { Index len; // (NlA) The actual length of the number stored in this BigUnsigned (in blocks) Blk *blk; // (NlA) Dynamically allocated array of the number blocks */ - + // MANAGEMENT protected: // These members generally defer to those in NumberlikeArray, possibly with slight changes. // It might be nice if one could request that constructors be inherited in C++. - + BigUnsigned(int, Index c) : NumberlikeArray(0, c) {} // Creates a BigUnsigned with a capacity - + void zapLeadingZeros() { // Decreases len to eliminate leading zeros while (len > 0 && blk[len - 1] == 0) len--; } - + //void allocate(Index c); // (NlA) Ensures the number array has at least the indicated capacity, maybe discarding contents //void allocateAndCopy(Index c); // (NlA) Ensures the number array has at least the indicated capacity, preserving its contents - + public: BigUnsigned() : NumberlikeArray() {} // Default constructor (value is 0) BigUnsigned(const BigUnsigned &x) : NumberlikeArray(x) {} // Copy constructor - + void operator=(const BigUnsigned &x) { // Assignment operator NumberlikeArray::operator =(x); } - + BigUnsigned(const Blk *b, Index l) : NumberlikeArray(b, l) { // Constructor from an array of blocks zapLeadingZeros(); } - + // Constructors from integral types BigUnsigned(unsigned long x); BigUnsigned( long x); @@ -78,7 +77,7 @@ class BigUnsigned : protected NumberlikeArray { BigUnsigned(unsigned short x); BigUnsigned( short x); ~BigUnsigned() {} // Destructor - + // CONVERTERS to integral types public: operator unsigned long () const; @@ -87,7 +86,7 @@ class BigUnsigned : protected NumberlikeArray { operator int () const; operator unsigned short() const; operator short() const; - + // PICKING APART // These accessors can be used to get the pieces of the number public: @@ -98,14 +97,20 @@ class BigUnsigned : protected NumberlikeArray { Blk getBlock(Index i) const { return i >= len ? 0 : blk[i]; } // Note how we replace one level of abstraction with another. Isn't that neat? bool isZero() const { return NumberlikeArray::isEmpty(); } // Often convenient for loops - + // COMPARISONS public: // Compares this to x like Perl's <=> CmpRes compareTo(const BigUnsigned &x) const; // Normal comparison operators - NumberlikeArray::operator ==; // (NlA) The body used to be `{ return compareTo(x) == equal; }'. For performance reasons we use NumberlikeArray code that only worries about (in)equality and doesn't waste time determining which is bigger - NumberlikeArray::operator !=; // (NlA) Ditto. + // Bug fixed 2006.04.24: Only we, not the user, can pass a BigUnsigned off as a + // NumberlikeArray, so we have to wrap == and !=. + bool operator ==(const BigUnsigned &x) const { + return NumberlikeArray::operator ==(x); + } + bool operator !=(const BigUnsigned &x) const { + return NumberlikeArray::operator !=(x); + } bool operator < (const BigUnsigned &x) const { return compareTo(x) == less ; } bool operator <=(const BigUnsigned &x) const { return compareTo(x) != greater; } bool operator >=(const BigUnsigned &x) const { return compareTo(x) != less ; } @@ -146,9 +151,10 @@ class BigUnsigned : protected NumberlikeArray { * c = a + b; // Now c == 50. * c.add(a, b); // Same effect but without the two bulk-copies. * c.divideWithRemainder(b, d); // 50 / 7; now d == 7 (quotient) and c == 1 (remainder). - * a.add(a, b); // Unsafe ``aliased'' call; causes a runtime error. + * a.add(a, b); // ``Aliased'' calls now do the right thing using a + * // temporary copy, but see note on divideWithRemainder. */ - + // PUT-HERE OPERATIONS public: /* These 3: Two read-only operands as arguments. Result left in *this. */ @@ -161,35 +167,32 @@ class BigUnsigned : protected NumberlikeArray { * and these differ from the semantics of primitive-type * / and % under division by zero. * Look in `BigUnsigned.cc' for details. + * `a.divideWithRemainder(b, a)' causes an exception: it doesn't make + * sense to write quotient and remainder into the same variable. */ void divideWithRemainder(const BigUnsigned &b, BigUnsigned &q); void divide(const BigUnsigned &a, const BigUnsigned &b) { - // Division, deprecated and provided for backward compatibility BigUnsigned a2(a); a2.divideWithRemainder(b, *this); // quotient now in *this // don't care about remainder left in a2 } void modulo(const BigUnsigned &a, const BigUnsigned &b) { - // Modular reduction, deprecated and provided for backward compatibility *this = a; BigUnsigned q; divideWithRemainder(b, q); // remainder now in *this // don't care about quotient left in q } - // Bitwise operations. Two read-only operands as arguments. Result left in *this. + // Bitwise operations. Result left in *this. // These are not provided for BigIntegers; I think that using them on BigIntegers // will discard the sign first. void bitAnd(const BigUnsigned &a, const BigUnsigned &b); // Bitwise AND void bitOr(const BigUnsigned &a, const BigUnsigned &b); // Bitwise OR void bitXor(const BigUnsigned &a, const BigUnsigned &b); // Bitwise XOR - - // These functions are declared but not defined. (Sorry.) - // Trying to call either will result in a link-time error. void bitShiftLeft(const BigUnsigned &a, unsigned int b); // Bitwise left shift void bitShiftRight(const BigUnsigned &a, unsigned int b); // Bitwise right shift - + // NORMAL OPERATORS // These perform the operation on this (to the left of the operator) // and x (to the right of the operator) and return a new BigUnsigned with the result. @@ -202,7 +205,12 @@ class BigUnsigned : protected NumberlikeArray { BigUnsigned operator &(const BigUnsigned &x) const; // Bitwise AND BigUnsigned operator |(const BigUnsigned &x) const; // Bitwise OR BigUnsigned operator ^(const BigUnsigned &x) const; // Bitwise XOR - + BigUnsigned operator <<(unsigned int b) const; // Bitwise left shift + BigUnsigned operator >>(unsigned int b) const; // Bitwise right shift + // Additional operators in an attempt to avoid overloading tangles. + BigUnsigned operator <<(int b) const; + BigUnsigned operator >>(int b) const; + // ASSIGNMENT OPERATORS // These perform the operation on this and x, storing the result into this. public: @@ -214,7 +222,12 @@ class BigUnsigned : protected NumberlikeArray { void operator &=(const BigUnsigned &x); // Bitwise AND void operator |=(const BigUnsigned &x); // Bitwise OR void operator ^=(const BigUnsigned &x); // Bitwise XOR - + void operator <<=(unsigned int b); // Bitwise left shift + void operator >>=(unsigned int b); // Bitwise right shift + // Additional operators in an attempt to avoid overloading tangles. + void operator <<=(int b); + void operator >>=(int b); + // INCREMENT/DECREMENT OPERATORS // These increase or decrease the number by 1. To discourage side effects, // these do not return *this, so prefix and postfix behave the same. @@ -223,7 +236,7 @@ class BigUnsigned : protected NumberlikeArray { void operator ++(int); // Postfix decrement void operator --( ); // Prefix increment void operator --(int); // Postfix decrement - + // Helper function that needs access to BigUnsigned internals friend Blk getShiftedBlock(const BigUnsigned &num, Index x, unsigned int y); }; @@ -272,22 +285,44 @@ inline BigUnsigned BigUnsigned::operator ^(const BigUnsigned &x) const { ans.bitXor(*this, x); return ans; } +inline BigUnsigned BigUnsigned::operator <<(unsigned int b) const { + BigUnsigned ans; + ans.bitShiftLeft(*this, b); + return ans; +} +inline BigUnsigned BigUnsigned::operator >>(unsigned int b) const { + BigUnsigned ans; + ans.bitShiftRight(*this, b); + return ans; +} +inline BigUnsigned BigUnsigned::operator <<(int b) const { + if (b < 0) + throw "BigUnsigned::operator <<(int): Negative shift amounts are not supported"; + return *this << (unsigned int)(b); +} +inline BigUnsigned BigUnsigned::operator >>(int b) const { + if (b < 0) + throw "BigUnsigned::operator >>(int): Negative shift amounts are not supported"; + return *this >> (unsigned int)(b); +} -// ASSIGNMENT OPERATORS -// These create a copy of this, then invoke the appropriate -// put-here operation on this, passing the copy and x. -// Exception: those updated for divideWithRemainder. +/* + * ASSIGNMENT OPERATORS + * + * Now the responsibility for making a temporary copy if necessary + * belongs to the put-here operations. I made this change on 2007.02.13 after + * Boris Dessy pointed out that the old implementation handled calls like + * "a *= a" badly: it translated them to essentially "a.multiply(aCopy, a)", + * which threw an exception. + */ inline void BigUnsigned::operator +=(const BigUnsigned &x) { - BigUnsigned thisCopy(*this); - add(thisCopy, x); + add(*this, x); } inline void BigUnsigned::operator -=(const BigUnsigned &x) { - BigUnsigned thisCopy(*this); - subtract(thisCopy, x); + subtract(*this, x); } inline void BigUnsigned::operator *=(const BigUnsigned &x) { - BigUnsigned thisCopy(*this); - multiply(thisCopy, x); + multiply(*this, x); } inline void BigUnsigned::operator /=(const BigUnsigned &x) { // Updated for divideWithRemainder @@ -304,16 +339,29 @@ inline void BigUnsigned::operator %=(const BigUnsigned &x) { // don't care about quotient left in q } inline void BigUnsigned::operator &=(const BigUnsigned &x) { - BigUnsigned thisCopy(*this); - bitAnd(thisCopy, x); + bitAnd(*this, x); } inline void BigUnsigned::operator |=(const BigUnsigned &x) { - BigUnsigned thisCopy(*this); - bitOr(thisCopy, x); + bitOr(*this, x); } inline void BigUnsigned::operator ^=(const BigUnsigned &x) { - BigUnsigned thisCopy(*this); - bitXor(thisCopy, x); + bitXor(*this, x); +} +inline void BigUnsigned::operator <<=(unsigned int b) { + bitShiftLeft(*this, b); +} +inline void BigUnsigned::operator >>=(unsigned int b) { + bitShiftRight(*this, b); +} +inline void BigUnsigned::operator <<=(int b) { + if (b < 0) + throw "BigUnsigned::operator <<=(int): Negative shift amounts are not supported"; + *this <<= (unsigned int)(b); +} +inline void BigUnsigned::operator >>=(int b) { + if (b < 0) + throw "BigUnsigned::operator >>=(int): Negative shift amounts are not supported"; + *this >>= (unsigned int)(b); } #endif