org.apache.hadoop.examples.pi.math.LongLong Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.hadoop.examples.pi.math;
import java.math.BigInteger;
/** Support 124-bit integer arithmetic. */
class LongLong {
static final int BITS_PER_LONG = 62;
static final int MID = BITS_PER_LONG >> 1;
static final int SIZE = BITS_PER_LONG << 1;
static final long FULL_MASK = (1L << BITS_PER_LONG) - 1;
static final long LOWER_MASK = FULL_MASK >>> MID;
static final long UPPER_MASK = LOWER_MASK << MID;
private long d0;
private long d1;
/** Set the values. */
LongLong set(long d0, long d1) {
this.d0 = d0;
this.d1 = d1;
return this;
}
/** And operation (&). */
long and(long mask) {
return d0 & mask;
}
/** Shift right operation (<<). */
long shiftRight(int n) {
return (d1 << (BITS_PER_LONG - n)) + (d0 >>> n);
}
/** Plus equal operation (+=). */
LongLong plusEqual(LongLong that) {
this.d0 += that.d0;
this.d1 += that.d1;
return this;
}
/** Convert this to a BigInteger. */
BigInteger toBigInteger() {
return BigInteger.valueOf(d1).shiftLeft(BITS_PER_LONG).add(BigInteger.valueOf(d0));
}
/** {@inheritDoc} */
@Override
public String toString() {
final int remainder = BITS_PER_LONG % 4;
return String.format("%x*2^%d + %016x", d1<> MID;
final long y0 = b & LOWER_MASK;
final long y1 = (b & UPPER_MASK) >> MID;
final long t = (x0 + x1)*(y0 + y1);
final long u = (x0 - x1)*(y0 - y1);
final long v = x1*y1;
final long tmp = (t - u)>>>1;
result.d0 = ((t + u)>>>1) - v + ((tmp << MID) & FULL_MASK);;
result.d1 = v + (tmp >> MID);
return result;
*/
final long a_lower = a & LOWER_MASK;
final long a_upper = (a & UPPER_MASK) >> MID;
final long b_lower = b & LOWER_MASK;
final long b_upper = (b & UPPER_MASK) >> MID;
final long tmp = a_lower*b_upper + a_upper*b_lower;
r.d0 = a_lower*b_lower + ((tmp << MID) & FULL_MASK);
r.d1 = a_upper*b_upper + (tmp >> MID);
return r;
}
}