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/*
Copyright (C) 1999 CERN - European Organization for Nuclear Research.
Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose
is hereby granted without fee, provided that the above copyright notice appear in all copies and
that both that copyright notice and this permission notice appear in supporting documentation.
CERN makes no representations about the suitability of this software for any purpose.
It is provided "as is" without expressed or implied warranty.
*/
package cern.colt.matrix.tbit;
/**
* Fixed sized (non resizable) bitvector. Upon instance construction a bitvector
* is told to hold a fixed number of bits - it's size. The size can be any
* number (need not be a power of 2 or so). The bits of a BitVector are
* indexed by nonnegative integers. Any attempt to access a bit at an
* index<0 || index>=size() will throw an
* IndexOutOfBoundsException.
*
* Individual indexed bits can be examined, set, or cleared. Subranges can
* quickly be extracted, copied and replaced. Quick iteration over subranges is
* provided by optimized internal iterators (forEach() methods). One
* BitVector may be used to modify the contents of another
* BitVector through logical AND, OR, XOR and other similar
* operations.
*
* All operations consider the bits 0..size()-1 and nothing else.
* Operations involving two bitvectors (like AND, OR, XOR, etc.) will throw an
* IllegalArgumentException if the secondary bit vector has a size
* smaller than the receiver.
*
* A BitVector is never automatically resized, but it can manually be
* grown or shrinked via setSize(...).
*
* For use cases that need to store several bits per information entity, quick
* accessors are provided that interpret subranges as 64 bit long
* integers.
*
* Why this class? Fist, boolean[] take one byte per stored bit. This
* class takes one bit per stored bit. Second, many applications find the
* semantics of java.util.BitSet not particularly helpful for their
* needs. Third, operations working on all bits of a bitvector are extremely
* quick. For example, on NT, Pentium Pro 200 Mhz, SunJDK1.2.2, java -classic,
* for two bitvectors A,B (both much larger than processor cache), the following
* results are obtained.
*
* - A.and(B) i.e. A = A & B --> runs at about 35 MB/sec
*
- A.cardinality(), i.e. determining the selectivity, the number of
* bits in state "true" --> runs at about 80 MB/sec
*
- Similar performance for
* or, xor, andNot, not, copy, replace, partFromTo, indexOf, clear etc.
*
* If you need extremely quick access to individual bits: Although getting and
* setting individual bits with methods get(...), set(...) and
* put(...)is quick, it is even quicker (but not safe) to use
* getQuick(...) and putQuick(...) or even
* QuickBitVector.
*
* Note that this implementation is not synchronized.
*
* @author [email protected]
* @version 1.01, 11/10/99
* @see QuickBitVector
* @see BitMatrix
* @see java.util.BitSet
*/
public class BitVector extends cern.colt.PersistentObject {
/*
* Bits are packed into arrays of "units." Currently a unit is a long, which
* consists of 64 bits, requiring 6 address bits. The choice of unit is
* determined purely by performance concerns.
*/
private static final long serialVersionUID = 1L;
/**
* The bits of this object. The ith bit is stored in bits[i/64] at bit
* position i % 64 (where bit position 0 refers to the least significant bit
* and 63 refers to the most significant bit).
*
* @serial
*/
protected long bits[];
protected int nbits; // the size
// IntProcedure for method indexOfFromTo(...)
private class IndexProcedure implements cern.colt.function.tint.IntProcedure {
private int foundPos = -1;
public boolean apply(int index) {
foundPos = index;
return false;
}
}
/**
* You normally need not use this method. Use this method only if
* performance is critical. Constructs a bit vector with the given backing
* bits and size. WARNING: For efficiency reasons and to keep memory
* usage low, the array is not copied. So if subsequently you modify
* the specified array directly via the [] operator, be sure you know what
* you're doing.
*
*
* A bitvector is modelled as a long array, i.e. long[] bits holds
* bits of a bitvector. Each long value holds 64 bits. The i-th bit is
* stored in bits[i/64] at bit position i % 64 (where bit position 0 refers
* to the least significant bit and 63 refers to the most significant bit).
*
* @throws IllegalArgumentException
* if size < 0 || size > bits.length*64.
*/
public BitVector(long[] bits, int size) {
elements(bits, size);
}
/**
* Constructs a bit vector that holds size bits. All bits are
* initially false.
*
* @param size
* the number of bits the bit vector shall have.
* @throws IllegalArgumentException
* if size < 0.
*/
public BitVector(int size) {
this(QuickBitVector.makeBitVector(size, 1), size);
}
/**
* Performs a logical AND of the receiver with another bit vector (A
* = A & B). The receiver is modified so that a bit in it has the value
* true if and only if it already had the value
* true and the corresponding bit in the other bit vector
* argument has the value true.
*
* @param other
* a bit vector.
* @throws IllegalArgumentException
* if size() > other.size().
*/
public void and(BitVector other) {
if (this == other)
return;
checkSize(other);
final long[] theBits = this.bits; // cached for speed.
final long[] otherBits = other.bits; // cached for speed.
for (int i = theBits.length; --i >= 0;)
theBits[i] &= otherBits[i];
}
/**
* Clears all of the bits in receiver whose corresponding bit is set in the
* other bitvector (A = A \ B). In other words, determines the difference
* (A=A\B) between two bitvectors.
*
* @param other
* a bitvector with which to mask the receiver.
* @throws IllegalArgumentException
* if size() > other.size().
*/
public void andNot(BitVector other) {
checkSize(other);
final long[] theBits = this.bits; // cached for speed.
final long[] otherBits = other.bits; // cached for speed.
for (int i = theBits.length; --i >= 0;)
theBits[i] &= ~otherBits[i];
}
/**
* Returns the number of bits currently in the true state.
* Optimized for speed. Particularly quick if the receiver is either sparse
* or dense.
*/
public int cardinality() {
int cardinality = 0;
int fullUnits = numberOfFullUnits();
final int bitsPerUnit = QuickBitVector.BITS_PER_UNIT;
// determine cardinality on full units
final long[] theBits = bits;
for (int i = fullUnits; --i >= 0;) {
long val = theBits[i];
if (val == -1L) { // all bits set?
cardinality += bitsPerUnit;
} else if (val != 0L) { // more than one bit set?
for (int j = bitsPerUnit; --j >= 0;) {
if ((val & (1L << j)) != 0)
cardinality++;
}
}
}
// determine cardinality on remaining partial unit, if any.
for (int j = numberOfBitsInPartialUnit(); --j >= 0;) {
if ((theBits[fullUnits] & (1L << j)) != 0)
cardinality++;
}
return cardinality;
}
/**
* Checks if the given range is within the contained array's bounds.
*/
protected static void checkRangeFromTo(int from, int to, int theSize) {
if (from < 0 || from > to || to >= theSize)
throw new IndexOutOfBoundsException("from: " + from + ", to: " + to + ", size=" + theSize);
}
/**
* Sanity check for operations requiring another bitvector with at least the
* same size.
*/
protected void checkSize(BitVector other) {
if (nbits > other.size())
throw new IllegalArgumentException("Incompatible sizes: size=" + nbits + ", other.size()=" + other.size());
}
/**
* Clears all bits of the receiver.
*/
public void clear() {
final long[] theBits = this.bits;
for (int i = theBits.length; --i >= 0;)
theBits[i] = 0L;
// new LongArrayList(bits).fillFromToWith(0,size()-1,0L);
}
/**
* Changes the bit with index bitIndex to the "clear" (
* false) state.
*
* @param bitIndex
* the index of the bit to be cleared.
* @throws IndexOutOfBoundsException
* if bitIndex<0 || bitIndex>=size()
*/
public void clear(int bitIndex) {
if (bitIndex < 0 || bitIndex >= nbits)
throw new IndexOutOfBoundsException(String.valueOf(bitIndex));
QuickBitVector.clear(bits, bitIndex);
}
/**
* Cloning this BitVector produces a new BitVector
* that is equal to it. The clone of the bit vector is another bit vector
* that has exactly the same bits set to true as this bit
* vector and the same current size, but independent state.
*
* @return a deep copy of this bit vector.
*/
public Object clone() {
BitVector clone = (BitVector) super.clone();
if (this.bits != null)
clone.bits = this.bits.clone();
return clone;
}
/**
* Returns a deep copy of the receiver; calls clone() and casts
* the result.
*
* @return a deep copy of the receiver.
*/
public BitVector copy() {
return (BitVector) clone();
}
/**
* You normally need not use this method. Use this method only if
* performance is critical. Returns the bit vector's backing bits.
* WARNING: For efficiency reasons and to keep memory usage low,
* the array is not copied. So if subsequently you modify the
* returned array directly via the [] operator, be sure you know what you're
* doing.
*
*
* A bitvector is modelled as a long array, i.e. long[] bits holds
* bits of a bitvector. Each long value holds 64 bits. The i-th bit is
* stored in bits[i/64] at bit position i % 64 (where bit position 0 refers
* to the least significant bit and 63 refers to the most significant bit).
*/
public long[] elements() {
return bits;
}
/**
* You normally need not use this method. Use this method only if
* performance is critical. Sets the bit vector's backing bits and size.
* WARNING: For efficiency reasons and to keep memory usage low,
* the array is not copied. So if subsequently you modify the
* specified array directly via the [] operator, be sure you know what
* you're doing.
*
*
* A bitvector is modelled as a long array, i.e. long[] bits holds
* bits of a bitvector. Each long value holds 64 bits. The i-th bit is
* stored in bits[i/64] at bit position i % 64 (where bit position 0 refers
* to the least significant bit and 63 refers to the most significant bit).
*
* @param bits
* the backing bits of the bit vector.
* @param size
* the number of bits the bit vector shall hold.
* @throws IllegalArgumentException
* if size < 0 || size > bits.length*64.
*/
public void elements(long[] bits, int size) {
if (size < 0 || size > bits.length * QuickBitVector.BITS_PER_UNIT)
throw new IllegalArgumentException();
this.bits = bits;
this.nbits = size;
}
/**
* Compares this object against the specified object. The result is
* true if and only if the argument is not null
* and is a BitVector object that has the same size as the
* receiver and the same bits set to true as the receiver. That
* is, for every nonnegative int index k,
*
*
* ((BitVector) obj).get(k) == this.get(k)
*
*
* must be true.
*
* @param obj
* the object to compare with.
* @return true if the objects are the same; false
* otherwise.
*/
public boolean equals(Object obj) {
if (obj == null || !(obj instanceof BitVector))
return false;
if (this == obj)
return true;
BitVector other = (BitVector) obj;
if (size() != other.size())
return false;
int fullUnits = numberOfFullUnits();
// perform logical comparison on full units
for (int i = fullUnits; --i >= 0;)
if (bits[i] != other.bits[i])
return false;
// perform logical comparison on remaining bits
int i = fullUnits * QuickBitVector.BITS_PER_UNIT;
for (int times = numberOfBitsInPartialUnit(); --times >= 0;) {
if (get(i) != other.get(i))
return false;
i++;
}
return true;
}
/**
* Applies a procedure to each bit index within the specified range that
* holds a bit in the given state. Starts at index from, moves
* rightwards to to. Useful, for example, if you want to copy bits
* into an image or somewhere else.
*
* Optimized for speed. Particularly quick if one of the following
* conditions holds
*
* - state==true and the receiver is sparse (
* cardinality() is small compared to size()).
*
- state==false and the receiver is dense (
* cardinality() is large compared to size()).
*
*
* @param from
* the leftmost search position, inclusive.
* @param to
* the rightmost search position, inclusive.
* @param state
* element to search for.
* @param procedure
* a procedure object taking as argument the current bit index.
* Stops iteration if the procedure returns false,
* otherwise continues.
* @return false if the procedure stopped before all elements where
* iterated over, true otherwise.
* @throws IndexOutOfBoundsException
* if (
* size()>0 && (from<0 || from>to || to>=size())
* ).
*/
public boolean forEachIndexFromToInState(int from, int to, boolean state,
cern.colt.function.tint.IntProcedure procedure) {
/*
* // this version is equivalent to the low level version below, but
* about 100 times slower for large ranges. if (nbits==0) return true;
* checkRangeFromTo(from, to, nbits); final long[] theBits = this.bits; //
* cached for speed int length=to-from+1; for (int i=from; --length >=
* 0; i++) { if (QuickBitVector.get(theBits,i)==state) { if
* (!function.apply(i)) return false; } } return true;
*/
/*
* This low level implementation exploits the fact that for any full
* unit one can determine in O(1) whether it contains at least one true
* bit, and whether it contains at least one false bit. Thus, 64 bits
* can often be skipped with one simple comparison if the vector is
* either sparse or dense.
*
* However, careful coding must be done for leading and/or trailing
* units which are not entirely contained in the query range.
*/
if (nbits == 0)
return true;
checkRangeFromTo(from, to, nbits);
// System.out.println("\n");
// System.out.println(this);
// System.out.println("from="+from+", to="+to+", bit="+state);
// Cache some vars for speed.
final long[] theBits = this.bits;
final int bitsPerUnit = QuickBitVector.BITS_PER_UNIT;
// Prepare
int fromUnit = QuickBitVector.unit(from);
int toUnit = QuickBitVector.unit(to);
int i = from; // current bitvector index
// Iterate over the leading partial unit, if any.
int bitIndex = QuickBitVector.offset(from);
int partialWidth;
if (bitIndex > 0) { // There exists a leading partial unit.
partialWidth = Math.min(to - from + 1, bitsPerUnit - bitIndex);
// System.out.println("partialWidth1="+partialWidth);
for (; --partialWidth >= 0; i++) {
if (QuickBitVector.get(theBits, i) == state) {
if (!procedure.apply(i))
return false;
}
}
fromUnit++; // leading partial unit is done.
}
if (i > to)
return true; // done
// If there is a trailing partial unit, then there is one full unit less
// to test.
bitIndex = QuickBitVector.offset(to);
if (bitIndex < bitsPerUnit - 1) {
toUnit--; // trailing partial unit needs to be tested extra.
partialWidth = bitIndex + 1;
} else {
partialWidth = 0;
}
// System.out.println("partialWidth2="+partialWidth);
// Iterate over all full units, if any.
// (It does not matter that iterating over partial units is a little bit
// slow,
// the only thing that matters is that iterating over full units is
// quick.)
long comparator;
if (state)
comparator = 0L;
else
comparator = ~0L; // all 64 bits set
// System.out.println("fromUnit="+fromUnit+", toUnit="+toUnit);
for (int unit = fromUnit; unit <= toUnit; unit++) {
long val = theBits[unit];
if (val != comparator) {
// at least one element within current unit matches.
// iterate over all bits within current unit.
if (state) {
for (int j = 0, k = bitsPerUnit; --k >= 0; i++) {
if ((val & (1L << j++)) != 0L) { // is bit set?
if (!procedure.apply(i))
return false;
}
}
} else {
for (int j = 0, k = bitsPerUnit; --k >= 0; i++) {
if ((val & (1L << j++)) == 0L) { // is bit cleared?
if (!procedure.apply(i))
return false;
}
}
}
} else {
i += bitsPerUnit;
}
}
// System.out.println("trail with i="+i);
// Iterate over trailing partial unit, if any.
for (; --partialWidth >= 0; i++) {
if (QuickBitVector.get(theBits, i) == state) {
if (!procedure.apply(i))
return false;
}
}
return true;
}
/**
* Returns from the bitvector the value of the bit with the specified index.
* The value is true if the bit with the index bitIndex is
* currently set; otherwise, returns false.
*
* @param bitIndex
* the bit index.
* @return the value of the bit with the specified index.
* @throws IndexOutOfBoundsException
* if bitIndex<0 || bitIndex>=size()
*/
public boolean get(int bitIndex) {
if (bitIndex < 0 || bitIndex >= nbits)
throw new IndexOutOfBoundsException(String.valueOf(bitIndex));
return QuickBitVector.get(bits, bitIndex);
}
/**
* Returns a long value representing bits of the receiver from index
* from to index to. Bits are returned as a long value
* with the return value having bit 0 set to bit from, ..., bit
* to-from set to bit to. All other bits of the
* return value are set to 0. If to-from+1==0 then returns zero (
* 0L).
*
* @param from
* index of start bit (inclusive).
* @param to
* index of end bit (inclusive).
* @return the specified bits as long value.
* @throws IndexOutOfBoundsException
* if
* from<0 || from>=size() || to<0 || to>=size() || to-from+1<0 || to-from+1>64
*/
public long getLongFromTo(int from, int to) {
int width = to - from + 1;
if (width == 0)
return 0L;
if (from < 0 || from >= nbits || to < 0 || to >= nbits || width < 0 || width > QuickBitVector.BITS_PER_UNIT)
throw new IndexOutOfBoundsException("from:" + from + ", to:" + to);
return QuickBitVector.getLongFromTo(bits, from, to);
}
/**
* Returns from the bitvector the value of the bit with the specified index;
* WARNING: Does not check preconditions. The value is true
* if the bit with the index bitIndex is currently set; otherwise,
* returns false.
*
*
* Provided with invalid parameters this method may return invalid values
* without throwing any exception. You should only use this method when
* you are absolutely sure that the index is within bounds. Precondition
* (unchecked): bitIndex >= 0 && bitIndex < size().
*
* @param bitIndex
* the bit index.
* @return the value of the bit with the specified index.
*/
public boolean getQuick(int bitIndex) {
return QuickBitVector.get(bits, bitIndex);
}
/**
* Returns a hash code value for the receiver. The hash code depends only on
* which bits have been set within the receiver. The algorithm used to
* compute it may be described as follows.
*
* Suppose the bits in the receiver were to be stored in an array of
* long integers called, say, bits, in such a
* manner that bit k is set in the receiver (for nonnegative
* values of k) if and only if the expression
*
*
* ((k >> 6) < bits.length) && ((bits[k >> 6] & (1L << (bit & 0x3F))) != 0)
*
*
* is true. Then the following definition of the hashCode
* method would be a correct implementation of the actual algorithm:
*
*
* public int hashCode() {
* long h = 1234;
* for (int i = bits.length; --i >= 0;) {
* h ˆ= bits[i] * (i + 1);
* }
* return (int) ((h >> 32) ˆ h);
* }
*
*
* Note that the hash code values change if the set of bits is altered.
*
* @return a hash code value for the receiver.
*/
public int hashCode() {
long h = 1234;
for (int i = bits.length; --i >= 0;)
h ^= bits[i] * (i + 1);
return (int) ((h >> 32) ^ h);
}
/**
* Returns the index of the first occurrence of the specified state. Returns
* -1 if the receiver does not contain this state. Searches
* between from, inclusive and to, inclusive.
*
* Optimized for speed. Preliminary performance (200Mhz Pentium Pro, JDK
* 1.2, NT): size=10^6, from=0, to=size-1, receiver contains matching state
* in the very end --> 0.002 seconds elapsed time.
*
* @param state
* state to search for.
* @param from
* the leftmost search position, inclusive.
* @param to
* the rightmost search position, inclusive.
* @return the index of the first occurrence of the element in the receiver;
* returns -1 if the element is not found.
* @exception IndexOutOfBoundsException
* if (
* size()>0 && (from<0 || from>to || to>=size())
* ).
*/
public int indexOfFromTo(int from, int to, boolean state) {
IndexProcedure indexProcedure = new IndexProcedure();
forEachIndexFromToInState(from, to, state, indexProcedure);
return indexProcedure.foundPos;
}
/**
* Performs a logical NOT on the bits of the receiver (A = ~A).
*/
public void not() {
final long[] theBits = this.bits;
for (int i = theBits.length; --i >= 0;)
theBits[i] = ~theBits[i];
}
/**
* Returns the number of bits used in the trailing PARTIAL unit. Returns
* zero if there is no such trailing partial unit.
*/
protected int numberOfBitsInPartialUnit() {
return QuickBitVector.offset(nbits);
}
/**
* Returns the number of units that are FULL (not PARTIAL).
*/
protected int numberOfFullUnits() {
return QuickBitVector.unit(nbits);
}
/**
* Performs a logical OR of the receiver with another bit vector (A =
* A | B). The receiver is modified so that a bit in it has the value
* true if and only if it either already had the value
* true or the corresponding bit in the other bit vector
* argument has the value true.
*
* @param other
* a bit vector.
* @throws IllegalArgumentException
* if size() > other.size().
*/
public void or(BitVector other) {
if (this == other)
return;
checkSize(other);
final long[] theBits = this.bits; // cached for speed.
final long[] otherBits = other.bits; // cached for speed.
for (int i = theBits.length; --i >= 0;)
theBits[i] |= otherBits[i];
}
/**
* Constructs and returns a new bit vector which is a copy of the given
* range. The new bitvector has size()==to-from+1.
*
* @param from
* the start index within the receiver, inclusive.
* @param to
* the end index within the receiver, inclusive.
* @throws IndexOutOfBoundsException
* if
* size()>0 && (from<0 || from>to || to>=size()))
* .
*/
public BitVector partFromTo(int from, int to) {
if (nbits == 0 || to == from - 1)
return new BitVector(0);
checkRangeFromTo(from, to, nbits);
int width = to - from + 1;
BitVector part = new BitVector(width);
part.replaceFromToWith(0, width - 1, this, from);
return part;
}
/**
* Sets the bit with index bitIndex to the state specified by
* value.
*
* @param bitIndex
* the index of the bit to be changed.
* @param value
* the value to be stored in the bit.
* @throws IndexOutOfBoundsException
* if bitIndex<0 || bitIndex>=size()
*/
public void put(int bitIndex, boolean value) {
if (bitIndex < 0 || bitIndex >= nbits)
throw new IndexOutOfBoundsException(String.valueOf(bitIndex));
if (value)
QuickBitVector.set(bits, bitIndex);
else
QuickBitVector.clear(bits, bitIndex);
}
/**
* Sets bits of the receiver from index from to index
* to to the bits of value. Bit from
* is set to bit 0 of value, ..., bit to is set to
* bit to-from of value. All other bits stay
* unaffected. If to-from+1==0 then does nothing.
*
* @param value
* the value to be copied into the receiver.
* @param from
* index of start bit (inclusive).
* @param to
* index of end bit (inclusive).
* @throws IndexOutOfBoundsException
* if
* from<0 || from>=size() || to<0 || to>=size() || to-from+1<0 || to-from+1>64
* .
*/
public void putLongFromTo(long value, int from, int to) {
int width = to - from + 1;
if (width == 0)
return;
if (from < 0 || from >= nbits || to < 0 || to >= nbits || width < 0 || width > QuickBitVector.BITS_PER_UNIT)
throw new IndexOutOfBoundsException("from:" + from + ", to:" + to);
QuickBitVector.putLongFromTo(bits, value, from, to);
}
/**
* Sets the bit with index bitIndex to the state specified by
* value; WARNING: Does not check preconditions.
*
*
* Provided with invalid parameters this method may set invalid values
* without throwing any exception. You should only use this method when
* you are absolutely sure that the index is within bounds. Precondition
* (unchecked): bitIndex >= 0 && bitIndex < size().
*
* @param bitIndex
* the index of the bit to be changed.
* @param value
* the value to be stored in the bit.
*/
public void putQuick(int bitIndex, boolean value) {
if (value)
QuickBitVector.set(bits, bitIndex);
else
QuickBitVector.clear(bits, bitIndex);
}
/**
* Replaces the bits of the receiver in the given range with the bits of
* another bit vector. Replaces the range [from,to] with the
* contents of the range [sourceFrom,sourceFrom+to-from], all
* inclusive. If source==this and the source and destination range
* intersect in an ambiguous way, then replaces as if using an intermediate
* auxiliary copy of the receiver.
*
* Optimized for speed. Preliminary performance (200Mhz Pentium Pro, JDK
* 1.2, NT): replace 10^6 ill aligned bits --> 0.02 seconds elapsed time.
*
* @param from
* the start index within the receiver, inclusive.
* @param to
* the end index within the receiver, inclusive.
* @param source
* the source bitvector to copy from.
* @param sourceFrom
* the start index within source, inclusive.
* @throws IndexOutOfBoundsException
* if
*
* size()>0 && (from<0 || from>to || to>=size() || sourceFrom<0 || sourceFrom+to-from+1>source.size()))
* .
*/
public void replaceFromToWith(int from, int to, BitVector source, int sourceFrom) {
if (nbits == 0 || to == from - 1)
return;
checkRangeFromTo(from, to, nbits);
int length = to - from + 1;
if (sourceFrom < 0 || sourceFrom + length > source.size()) {
throw new IndexOutOfBoundsException();
}
if (source.bits == this.bits && from <= sourceFrom && sourceFrom <= to) { // dangerous
// intersection
source = source.copy();
}
final long[] theBits = this.bits; // cached for speed.
final long[] sourceBits = source.bits; // cached for speed.
/*
* This version is equivalent to the version below but 20 times
* slower... for (int i=from; --length >= 0; i++, sourceFrom++) {
* QuickBitVector.put(theBits,i,QuickBitVector.get(sourceBits,sourceFrom)); }
*/
// Low level implementation for speed.
// This could be done even faster by implementing on even lower levels.
// But then the code would probably become a "don't touch" piece.
final int width = to - from + 1;
final int blocks = QuickBitVector.unit(width); // width/64
final int bitsPerUnit = QuickBitVector.BITS_PER_UNIT;
final int bitsPerUnitMinusOne = bitsPerUnit - 1;
// copy entire 64 bit blocks, if any.
for (int i = blocks; --i >= 0;) {
long val = QuickBitVector.getLongFromTo(sourceBits, sourceFrom, sourceFrom + bitsPerUnitMinusOne);
QuickBitVector.putLongFromTo(theBits, val, from, from + bitsPerUnitMinusOne);
sourceFrom += bitsPerUnit;
from += bitsPerUnit;
}
// copy trailing bits, if any.
int offset = QuickBitVector.offset(width); // width%64
long val = QuickBitVector.getLongFromTo(sourceBits, sourceFrom, sourceFrom + offset - 1);
QuickBitVector.putLongFromTo(theBits, val, from, from + offset - 1);
}
/**
* Sets the bits in the given range to the state specified by value
* .
*
* Optimized for speed. Preliminary performance (200Mhz Pentium Pro, JDK
* 1.2, NT): replace 10^6 ill aligned bits --> 0.002 seconds elapsed time.
*
* @param from
* the start index, inclusive.
* @param to
* the end index, inclusive.
* @param value
* the value to be stored in the bits of the range.
* @throws IndexOutOfBoundsException
* if
* size()>0 && (from<0 || from>to || to>=size())
* .
*/
public void replaceFromToWith(int from, int to, boolean value) {
if (nbits == 0 || to == from - 1)
return;
checkRangeFromTo(from, to, nbits);
final long[] theBits = this.bits; // cached for speed
int fromUnit = QuickBitVector.unit(from);
int fromOffset = QuickBitVector.offset(from);
int toUnit = QuickBitVector.unit(to);
int toOffset = QuickBitVector.offset(to);
int bitsPerUnit = QuickBitVector.BITS_PER_UNIT;
long filler;
if (value)
filler = ~0L;
else
filler = 0L;
int bitIndex = from;
if (fromUnit == toUnit) { // only one unit to do
QuickBitVector.putLongFromTo(theBits, filler, bitIndex, bitIndex + to - from);
// slower: for (; bitIndex<=to; )
// QuickBitVector.put(theBits,bitIndex++,value);
return;
}
// treat leading partial unit, if any.
if (fromOffset > 0) { // fix by Olivier Janssens
QuickBitVector.putLongFromTo(theBits, filler, bitIndex, bitIndex + bitsPerUnit - fromOffset);
bitIndex += bitsPerUnit - fromOffset + 1;
/*
* slower: for (int i=bitsPerUnit-fromOffset; --i >= 0; ) {
* QuickBitVector.put(theBits,bitIndex++,value); }
*/
fromUnit++;
}
if (toOffset < bitsPerUnit - 1)
toUnit--; // there is a trailing partial unit
// treat full units, if any.
for (int i = fromUnit; i <= toUnit;)
theBits[i++] = filler;
if (fromUnit <= toUnit)
bitIndex += (toUnit - fromUnit + 1) * bitsPerUnit;
// treat trailing partial unit, if any.
if (toOffset < bitsPerUnit - 1) {
QuickBitVector.putLongFromTo(theBits, filler, bitIndex, to);
/*
* slower: for (int i=toOffset+1; --i >= 0; ) {
* QuickBitVector.put(theBits,bitIndex++,value); }
*/
}
}
/**
* Changes the bit with index bitIndex to the "set" (true)
* state.
*
* @param bitIndex
* the index of the bit to be set.
* @throws IndexOutOfBoundsException
* if bitIndex<0 || bitIndex>=size()
*/
public void set(int bitIndex) {
if (bitIndex < 0 || bitIndex >= nbits)
throw new IndexOutOfBoundsException(String.valueOf(bitIndex));
QuickBitVector.set(bits, bitIndex);
}
/**
* Shrinks or expands the receiver so that it holds newSize bits.
* If the receiver is expanded, additional false bits are added to
* the end. If the receiver is shrinked, all bits between the old size and
* the new size are lost; their memory is subject to garbage collection.
* (This method introduces a new backing array of elements. WARNING: if you
* have more than one BitVector or BitMatrix sharing identical backing
* elements, be sure you know what you are doing.)
*
* @param newSize
* the number of bits the bit vector shall have.
* @throws IllegalArgumentException
* if size < 0.
*/
public void setSize(int newSize) {
if (newSize != size()) {
BitVector newVector = new BitVector(newSize);
newVector.replaceFromToWith(0, Math.min(size(), newSize) - 1, this, 0);
elements(newVector.elements(), newSize);
}
}
/**
* Returns the size of the receiver.
*/
public int size() {
return nbits;
}
/**
* Returns a string representation of the receiver. For every index for
* which the receiver contains a bit in the "set" (true) state, the
* decimal representation of that index is included in the result. Such
* indeces are listed in order from lowest to highest, separated by
* ", " (a comma and a space) and surrounded by braces.
*
* @return a string representation of this bit vector.
*/
public String toString() {
StringBuffer buffer = new StringBuffer(nbits);
String separator = "";
buffer.append('{');
for (int i = 0; i < nbits; i++) {
if (get(i)) {
buffer.append(separator);
separator = ", ";
buffer.append(i);
}
}
buffer.append('}');
return buffer.toString();
}
/**
* Performs a logical XOR of the receiver with another bit vector (A
* = A ^ B). The receiver is modified so that a bit in it has the value
* true if and only if one of the following statements holds:
*
* - The bit initially has the value
true, and the
* corresponding bit in the argument has the value false.
* - The bit initially has the value
false, and the
* corresponding bit in the argument has the value true.
*
*
* @param other
* a bit vector.
* @throws IllegalArgumentException
* if size() > other.size().
*/
public void xor(BitVector other) {
checkSize(other);
final long[] theBits = this.bits; // cached for speed.
final long[] otherBits = other.bits; // cached for speed.
for (int i = theBits.length; --i >= 0;)
theBits[i] ^= otherBits[i];
}
}