org.apache.hadoop.examples.terasort.Unsigned16 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.terasort;
import java.io.DataInput;
import java.io.DataOutput;
import java.io.IOException;
import org.apache.hadoop.io.Writable;
/**
* An unsigned 16 byte integer class that supports addition, multiplication,
* and left shifts.
*/
class Unsigned16 implements Writable {
private long hi8;
private long lo8;
public Unsigned16() {
hi8 = 0;
lo8 = 0;
}
public Unsigned16(long l) {
hi8 = 0;
lo8 = l;
}
public Unsigned16(Unsigned16 other) {
hi8 = other.hi8;
lo8 = other.lo8;
}
@Override
public boolean equals(Object o) {
if (o instanceof Unsigned16) {
Unsigned16 other = (Unsigned16) o;
return other.hi8 == hi8 && other.lo8 == lo8;
}
return false;
}
@Override
public int hashCode() {
return (int) lo8;
}
/**
* Parse a hex string
* @param s the hex string
*/
public Unsigned16(String s) throws NumberFormatException {
set(s);
}
/**
* Set the number from a hex string
* @param s the number in hexadecimal
* @throws NumberFormatException if the number is invalid
*/
public void set(String s) throws NumberFormatException {
hi8 = 0;
lo8 = 0;
final long lastDigit = 0xfl << 60;
for (int i = 0; i < s.length(); ++i) {
int digit = getHexDigit(s.charAt(i));
if ((lastDigit & hi8) != 0) {
throw new NumberFormatException(s + " overflowed 16 bytes");
}
hi8 <<= 4;
hi8 |= (lo8 & lastDigit) >>> 60;
lo8 <<= 4;
lo8 |= digit;
}
}
/**
* Set the number to a given long.
* @param l the new value, which is treated as an unsigned number
*/
public void set(long l) {
lo8 = l;
hi8 = 0;
}
/**
* Map a hexadecimal character into a digit.
* @param ch the character
* @return the digit from 0 to 15
* @throws NumberFormatException
*/
private static int getHexDigit(char ch) throws NumberFormatException {
if (ch >= '0' && ch <= '9') {
return ch - '0';
}
if (ch >= 'a' && ch <= 'f') {
return ch - 'a' + 10;
}
if (ch >= 'A' && ch <= 'F') {
return ch - 'A' + 10;
}
throw new NumberFormatException(ch + " is not a valid hex digit");
}
private static final Unsigned16 TEN = new Unsigned16(10);
public static Unsigned16 fromDecimal(String s) throws NumberFormatException {
Unsigned16 result = new Unsigned16();
Unsigned16 tmp = new Unsigned16();
for(int i=0; i < s.length(); i++) {
char ch = s.charAt(i);
if (ch < '0' || ch > '9') {
throw new NumberFormatException(ch + " not a valid decimal digit");
}
int digit = ch - '0';
result.multiply(TEN);
tmp.set(digit);
result.add(tmp);
}
return result;
}
/**
* Return the number as a hex string.
*/
public String toString() {
if (hi8 == 0) {
return Long.toHexString(lo8);
} else {
StringBuilder result = new StringBuilder();
result.append(Long.toHexString(hi8));
String loString = Long.toHexString(lo8);
for(int i=loString.length(); i < 16; ++i) {
result.append('0');
}
result.append(loString);
return result.toString();
}
}
/**
* Get a given byte from the number.
* @param b the byte to get with 0 meaning the most significant byte
* @return the byte or 0 if b is outside of 0..15
*/
public byte getByte(int b) {
if (b >= 0 && b < 16) {
if (b < 8) {
return (byte) (hi8 >> (56 - 8*b));
} else {
return (byte) (lo8 >> (120 - 8*b));
}
}
return 0;
}
/**
* Get the hexadecimal digit at the given position.
* @param p the digit position to get with 0 meaning the most significant
* @return the character or '0' if p is outside of 0..31
*/
public char getHexDigit(int p) {
byte digit = getByte(p / 2);
if (p % 2 == 0) {
digit >>>= 4;
}
digit &= 0xf;
if (digit < 10) {
return (char) ('0' + digit);
} else {
return (char) ('A' + digit - 10);
}
}
/**
* Get the high 8 bytes as a long.
*/
public long getHigh8() {
return hi8;
}
/**
* Get the low 8 bytes as a long.
*/
public long getLow8() {
return lo8;
}
/**
* Multiple the current number by a 16 byte unsigned integer. Overflow is not
* detected and the result is the low 16 bytes of the result. The numbers
* are divided into 32 and 31 bit chunks so that the product of two chucks
* fits in the unsigned 63 bits of a long.
* @param b the other number
*/
void multiply(Unsigned16 b) {
// divide the left into 4 32 bit chunks
long[] left = new long[4];
left[0] = lo8 & 0xffffffffl;
left[1] = lo8 >>> 32;
left[2] = hi8 & 0xffffffffl;
left[3] = hi8 >>> 32;
// divide the right into 5 31 bit chunks
long[] right = new long[5];
right[0] = b.lo8 & 0x7fffffffl;
right[1] = (b.lo8 >>> 31) & 0x7fffffffl;
right[2] = (b.lo8 >>> 62) + ((b.hi8 & 0x1fffffffl) << 2);
right[3] = (b.hi8 >>> 29) & 0x7fffffffl;
right[4] = (b.hi8 >>> 60);
// clear the cur value
set(0);
Unsigned16 tmp = new Unsigned16();
for(int l=0; l < 4; ++l) {
for (int r=0; r < 5; ++r) {
long prod = left[l] * right[r];
if (prod != 0) {
int off = l*32 + r*31;
tmp.set(prod);
tmp.shiftLeft(off);
add(tmp);
}
}
}
}
/**
* Add the given number into the current number.
* @param b the other number
*/
public void add(Unsigned16 b) {
long sumHi;
long sumLo;
long reshibit, hibit0, hibit1;
sumHi = hi8 + b.hi8;
hibit0 = (lo8 & 0x8000000000000000L);
hibit1 = (b.lo8 & 0x8000000000000000L);
sumLo = lo8 + b.lo8;
reshibit = (sumLo & 0x8000000000000000L);
if ((hibit0 & hibit1) != 0 | ((hibit0 ^ hibit1) != 0 && reshibit == 0))
sumHi++; /* add carry bit */
hi8 = sumHi;
lo8 = sumLo;
}
/**
* Shift the number a given number of bit positions. The number is the low
* order bits of the result.
* @param bits the bit positions to shift by
*/
public void shiftLeft(int bits) {
if (bits != 0) {
if (bits < 64) {
hi8 <<= bits;
hi8 |= (lo8 >>> (64 - bits));
lo8 <<= bits;
} else if (bits < 128) {
hi8 = lo8 << (bits - 64);
lo8 = 0;
} else {
hi8 = 0;
lo8 = 0;
}
}
}
@Override
public void readFields(DataInput in) throws IOException {
hi8 = in.readLong();
lo8 = in.readLong();
}
@Override
public void write(DataOutput out) throws IOException {
out.writeLong(hi8);
out.writeLong(lo8);
}
}