poi/src/java/org/apache/poi/util/BitField.java

363 lines
10 KiB
Java

/* ====================================================================
* The Apache Software License, Version 1.1
*
* Copyright (c) 2003 The Apache Software Foundation. All rights
* reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. The end-user documentation included with the redistribution,
* if any, must include the following acknowledgment:
* "This product includes software developed by the
* Apache Software Foundation (http://www.apache.org/)."
* Alternately, this acknowledgment may appear in the software itself,
* if and wherever such third-party acknowledgments normally appear.
*
* 4. The names "Apache" and "Apache Software Foundation" and
* "Apache POI" must not be used to endorse or promote products
* derived from this software without prior written permission. For
* written permission, please contact apache@apache.org.
*
* 5. Products derived from this software may not be called "Apache",
* "Apache POI", nor may "Apache" appear in their name, without
* prior written permission of the Apache Software Foundation.
*
* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
* DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
* USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
* ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
* ====================================================================
*
* This software consists of voluntary contributions made by many
* individuals on behalf of the Apache Software Foundation. For more
* information on the Apache Software Foundation, please see
* <http://www.apache.org/>.
*/
package org.apache.poi.util;
/**
* Manage operations dealing with bit-mapped fields.
*
* @author Marc Johnson (mjohnson at apache dot org)
* @author Andrew C. Oliver (acoliver at apache dot org)
*/
public class BitField
{
private final int _mask;
private final int _shift_count;
/**
* Create a BitField instance
*
* @param mask the mask specifying which bits apply to this
* BitField. Bits that are set in this mask are the
* bits that this BitField operates on
*/
public BitField(final int mask)
{
_mask = mask;
int count = 0;
int bit_pattern = mask;
if (bit_pattern != 0)
{
while ((bit_pattern & 1) == 0)
{
count++;
bit_pattern >>= 1;
}
}
_shift_count = count;
}
/**
* Obtain the value for the specified BitField, appropriately
* shifted right. Many users of a BitField will want to treat the
* specified bits as an int value, and will not want to be aware
* that the value is stored as a BitField (and so shifted left so
* many bits)
*
* @param holder the int data containing the bits we're interested
* in
*
* @return the selected bits, shifted right appropriately
*/
public int getValue(final int holder)
{
return getRawValue(holder) >> _shift_count;
}
/**
* Obtain the value for the specified BitField, appropriately
* shifted right, as a short. Many users of a BitField will want
* to treat the specified bits as an int value, and will not want
* to be aware that the value is stored as a BitField (and so
* shifted left so many bits)
*
* @param holder the short data containing the bits we're
* interested in
*
* @return the selected bits, shifted right appropriately
*/
public short getShortValue(final short holder)
{
return ( short ) getValue(holder);
}
/**
* Obtain the value for the specified BitField, unshifted
*
* @param holder the int data containing the bits we're interested
* in
*
* @return the selected bits
*/
public int getRawValue(final int holder)
{
return (holder & _mask);
}
/**
* Obtain the value for the specified BitField, unshifted
*
* @param holder the short data containing the bits we're
* interested in
*
* @return the selected bits
*/
public short getShortRawValue(final short holder)
{
return ( short ) getRawValue(holder);
}
/**
* Is the field set or not? This is most commonly used for a
* single-bit field, which is often used to represent a boolean
* value; the results of using it for a multi-bit field is to
* determine whether *any* of its bits are set
*
* @param holder the int data containing the bits we're interested
* in
*
* @return true if any of the bits are set, else false
*/
public boolean isSet(final int holder)
{
return (holder & _mask) != 0;
}
/**
* Are all of the bits set or not? This is a stricter test than
* isSet, in that all of the bits in a multi-bit set must be set
* for this method to return true
*
* @param holder the int data containing the bits we're interested
* in
*
* @return true if all of the bits are set, else false
*/
public boolean isAllSet(final int holder)
{
return (holder & _mask) == _mask;
}
/**
* Replace the bits with new values.
*
* @param holder the int data containint the bits we're interested
* in
* @param value the new value for the specified bits
*
* @return the value of holder with the bits from the value
* parameter replacing the old bits
*/
public int setValue(final int holder, final int value)
{
return (holder & ~_mask) | ((value << _shift_count) & _mask);
}
/**
* Replace the bits with new values.
*
* @param holder the short data containing the bits we're
* interested in
* @param value the new value for the specified bits
*
* @return the value of holder with the bits from the value
* parameter replacing the old bits
*/
public short setShortValue(final short holder, final short value)
{
return ( short ) setValue(holder, value);
}
/**
* Clear the bits.
*
* @param holder the int data containing the bits we're interested
* in
*
* @return the value of holder with the specified bits cleared
* (set to 0)
*/
public int clear(final int holder)
{
return holder & ~_mask;
}
/**
* Clear the bits.
*
* @param holder the short data containing the bits we're
* interested in
*
* @return the value of holder with the specified bits cleared
* (set to 0)
*/
public short clearShort(final short holder)
{
return ( short ) clear(holder);
}
/**
* Clear the bits.
*
* @param holder the byte data containing the bits we're
* interested in
*
* @return the value of holder with the specified bits cleared
* (set to 0)
*/
public byte clearByte(final byte holder)
{
return ( byte ) clear(holder);
}
/**
* Set the bits.
*
* @param holder the int data containing the bits we're interested
* in
*
* @return the value of holder with the specified bits set to 1
*/
public int set(final int holder)
{
return holder | _mask;
}
/**
* Set the bits.
*
* @param holder the short data containing the bits we're
* interested in
*
* @return the value of holder with the specified bits set to 1
*/
public short setShort(final short holder)
{
return ( short ) set(holder);
}
/**
* Set the bits.
*
* @param holder the byte data containing the bits we're
* interested in
*
* @return the value of holder with the specified bits set to 1
*/
public byte setByte(final byte holder)
{
return ( byte ) set(holder);
}
/**
* Set a boolean BitField
*
* @param holder the int data containing the bits we're interested
* in
* @param flag indicating whether to set or clear the bits
*
* @return the value of holder with the specified bits set or
* cleared
*/
public int setBoolean(final int holder, final boolean flag)
{
return flag ? set(holder)
: clear(holder);
}
/**
* Set a boolean BitField
*
* @param holder the short data containing the bits we're
* interested in
* @param flag indicating whether to set or clear the bits
*
* @return the value of holder with the specified bits set or
* cleared
*/
public short setShortBoolean(final short holder, final boolean flag)
{
return flag ? setShort(holder)
: clearShort(holder);
}
/**
* Set a boolean BitField
*
* @param holder the byte data containing the bits we're
* interested in
* @param flag indicating whether to set or clear the bits
*
* @return the value of holder with the specified bits set or
* cleared
*/
public byte setByteBoolean(final byte holder, final boolean flag)
{
return flag ? setByte(holder)
: clearByte(holder);
}
} // end public class BitField