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8022180: BigInteger Burnikel-Ziegler quotient and remainder calculation assumes quotient parameter is zero

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Clear the quotient in divideAndRemainderBurnikelZiegler() if the divisor is larger than the dividend.

Reviewed-by: alanb, bpb
This commit is contained in:
Timothy Buktu 2013-08-12 16:21:10 -07:00 committed by Brian Burkhalter
parent f0836f6924
commit e3b61c033b
2 changed files with 12 additions and 10 deletions
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4
jdk/src/share/classes/java/math/MutableBigInteger.java
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@ -1242,6 +1242,9 @@ class MutableBigInteger {
int r = intLen; int r = intLen;
int s = b.intLen; int s = b.intLen;
// Clear the quotient
quotient.offset = quotient.intLen = 0;
if (r < s) { if (r < s) {
return this; return this;
} else { } else {
@ -1276,7 +1279,6 @@ class MutableBigInteger {
// do schoolbook division on blocks, dividing 2-block numbers by 1-block numbers // do schoolbook division on blocks, dividing 2-block numbers by 1-block numbers
MutableBigInteger qi = new MutableBigInteger(); MutableBigInteger qi = new MutableBigInteger();
MutableBigInteger ri; MutableBigInteger ri;
quotient.offset = quotient.intLen = 0;
for (int i=t-2; i > 0; i--) { for (int i=t-2; i > 0; i--) {
// step 8a: compute (qi,ri) such that z=b*qi+ri // step 8a: compute (qi,ri) such that z=b*qi+ri
ri = z.divide2n1n(bShifted, qi); ri = z.divide2n1n(bShifted, qi);

18
jdk/test/java/math/BigInteger/BigIntegerTest.java
View File

@ -74,10 +74,10 @@ public class BigIntegerTest {
static final int ORDER_SMALL = 60; static final int ORDER_SMALL = 60;
static final int ORDER_MEDIUM = 100; static final int ORDER_MEDIUM = 100;
// #bits for testing Karatsuba and Burnikel-Ziegler // #bits for testing Karatsuba
static final int ORDER_KARATSUBA = 1800; static final int ORDER_KARATSUBA = 1800;
// #bits for testing Toom-Cook // #bits for testing Toom-Cook and Burnikel-Ziegler
static final int ORDER_TOOM_COOK = 3000; static final int ORDER_TOOM_COOK = 4000;
// #bits for testing Karatsuba squaring // #bits for testing Karatsuba squaring
static final int ORDER_KARATSUBA_SQUARE = 3200; static final int ORDER_KARATSUBA_SQUARE = 3200;
// #bits for testing Toom-Cook squaring // #bits for testing Toom-Cook squaring
@ -964,12 +964,12 @@ public class BigIntegerTest {
nextProbablePrime(); nextProbablePrime();
arithmetic(order1); // small numbers arithmetic(order1); // small numbers
arithmetic(order3); // Karatsuba / Burnikel-Ziegler range arithmetic(order3); // Karatsuba range
arithmetic(order4); // Toom-Cook range arithmetic(order4); // Toom-Cook / Burnikel-Ziegler range
divideAndRemainder(order1); // small numbers divideAndRemainder(order1); // small numbers
divideAndRemainder(order3); // Karatsuba / Burnikel-Ziegler range divideAndRemainder(order3); // Karatsuba range
divideAndRemainder(order4); // Toom-Cook range divideAndRemainder(order4); // Toom-Cook / Burnikel-Ziegler range
pow(order1); pow(order1);
pow(order3); pow(order3);
@ -989,8 +989,8 @@ public class BigIntegerTest {
byteArrayConv(order1); byteArrayConv(order1);
modInv(order1); // small numbers modInv(order1); // small numbers
modInv(order3); // Karatsuba / Burnikel-Ziegler range modInv(order3); // Karatsuba range
modInv(order4); // Toom-Cook range modInv(order4); // Toom-Cook / Burnikel-Ziegler range
modExp(order1, order2); modExp(order1, order2);
modExp2(order1); modExp2(order1);