This is actually going to be version 2007.02.16 .

[bigint/bigint.git] / BigInteger.cc

diff --git a/BigInteger.cc b/BigInteger.cc
index 471d056..ba49180 100644 (file)
--- a/BigInteger.cc
+++ b/BigInteger.cc
@@ -1,6 +1,5 @@
 /*
 * Matt McCutchen's Big Integer Library
-* http://mysite.verizon.net/mccutchen/bigint/
 */
 
 #include "BigInteger.hh"
@@ -67,7 +66,7 @@ BigInteger::BigInteger(unsigned long x) {
                sign = zero; // NumberlikeArray did the rest
        else {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = positive;
                len = 1;
                blk[0] = Blk(x);
@@ -77,13 +76,13 @@ BigInteger::BigInteger(unsigned long x) {
 BigInteger::BigInteger(long x) {
        if (x > 0) {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = positive;
                len = 1;
                blk[0] = Blk(x);
        } else if (x < 0) {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = negative;
                len = 1;
                blk[0] = Blk(-x);
@@ -96,7 +95,7 @@ BigInteger::BigInteger(unsigned int x) {
                sign = zero;
        else {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = positive;
                len = 1;
                blk[0] = Blk(x);
@@ -106,13 +105,13 @@ BigInteger::BigInteger(unsigned int x) {
 BigInteger::BigInteger(int x) {
        if (x > 0) {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = positive;
                len = 1;
                blk[0] = Blk(x);
        } else if (x < 0) {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = negative;
                len = 1;
                blk[0] = Blk(-x);
@@ -125,7 +124,7 @@ BigInteger::BigInteger(unsigned short x) {
                sign = zero;
        else {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = positive;
                len = 1;
                blk[0] = Blk(x);
@@ -135,13 +134,13 @@ BigInteger::BigInteger(unsigned short x) {
 BigInteger::BigInteger(short x) {
        if (x > 0) {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = positive;
                len = 1;
                blk[0] = Blk(x);
        } else if (x < 0) {
                cap = 1;
-               blk2 = new Blk[1];
+               blk = new Blk[1];
                sign = negative;
                len = 1;
                blk[0] = Blk(-x);
@@ -311,11 +310,18 @@ BigInteger::CmpRes BigInteger::compareTo(const BigInteger &x) const {
 // These do some messing around to determine the sign of the result,
 // then call one of BigUnsigned's put-heres.
 
+// See remarks about aliased calls in BigUnsigned.cc .
+#define DOTR_ALIASED(cond, op) \
+       if (cond) { \
+               BigInteger tmpThis; \
+               tmpThis.op; \
+               *this = tmpThis; \
+               return; \
+       }
+
 // Addition
 void BigInteger::add(const BigInteger &a, const BigInteger &b) {
-       // Block unsafe calls
-       if (this == &a || this == &b)
-               throw "BigInteger::add: One of the arguments is the invoked object";
+       DOTR_ALIASED(this == &a || this == &b, add(a, b));
        // If one argument is zero, copy the other.
        if (a.sign == zero)
                operator =(b);
@@ -352,15 +358,15 @@ void BigInteger::add(const BigInteger &a, const BigInteger &b) {
 void BigInteger::subtract(const BigInteger &a, const BigInteger &b) {
        // Notice that this routine is identical to BigInteger::add,
        // if one replaces b.sign by its opposite.
-       // Block unsafe calls
-       if (this == &a || this == &b)
-               throw "BigInteger::subtract: One of the arguments is the invoked object";
+       DOTR_ALIASED(this == &a || this == &b, subtract(a, b));
        // If a is zero, copy b and flip its sign.  If b is zero, copy a.
        if (a.sign == zero) {
                BigUnsigned::operator =(b);
-               sign = Sign(-sign);
+               // Take the negative of _b_'s, sign, not ours.
+               // Bug pointed out by Sam Larkin on 2005.03.30.
+               sign = Sign(-b.sign);
        } else if (b.sign == zero)
-    operator =(a);
+               operator =(a);
        // If their signs differ, take a.sign and add the magnitudes.
        else if (a.sign != b.sign) {
                sign = a.sign;
@@ -391,9 +397,7 @@ void BigInteger::subtract(const BigInteger &a, const BigInteger &b) {
 
 // Multiplication
 void BigInteger::multiply(const BigInteger &a, const BigInteger &b) {
-       // Block unsafe calls
-       if (this == &a || this == &b)
-               throw "BigInteger::multiply: One of the arguments is the invoked object";
+       DOTR_ALIASED(this == &a || this == &b, multiply(a, b));
        // If one object is zero, copy zero and return.
        if (a.sign == zero || b.sign == zero) {
                sign = zero;
@@ -430,9 +434,16 @@ void BigInteger::multiply(const BigInteger &a, const BigInteger &b) {
 *      -4      -3      1       -1
 */
 void BigInteger::divideWithRemainder(const BigInteger &b, BigInteger &q) {
-       // Block unsafe calls
-       if (this == &b || this == &q || &b == &q)
-               throw "BigInteger::divideWithRemainder: One of the arguments is the invoked object";
+       // Defend against aliased calls;
+       // same idea as in BigUnsigned::divideWithRemainder .
+       if (this == &q)
+               throw "BigInteger::divideWithRemainder: Cannot write quotient and remainder into the same variable";
+       if (this == &b || &q == &b) {
+               BigInteger tmpB(b);
+               divideWithRemainder(tmpB, q);
+               return;
+       }
+       
        // Division by zero gives quotient 0 and remainder *this
        if (b.sign == zero) {
                q.len = 0;
@@ -506,9 +517,7 @@ void BigInteger::divideWithRemainder(const BigInteger &b, BigInteger &q) {
 
 // Negation
 void BigInteger::negate(const BigInteger &a) {
-       // Block unsafe calls
-       if (this == &a)
-               throw "BigInteger::negate: The argument is the invoked object";
+       DOTR_ALIASED(this == &a, negate(a));
        // Copy a's magnitude
        BigUnsigned::operator =(a);
        // Copy the opposite of a.sign