eaglercraft-1.8/sources/main/java/org/apache/commons/lang3/BitField.java
2022-12-25 01:12:28 -08:00

345 lines
9.6 KiB
Java

/*
* 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.commons.lang3;
/**
* <p>
* Supports operations on bit-mapped fields. Instances of this class can be used
* to store a flag or data within an {@code int}, {@code short} or {@code byte}.
* </p>
*
* <p>
* Each {@code BitField} is constructed with a mask value, which indicates the
* bits that will be used to store and retrieve the data for that field. For
* instance, the mask {@code 0xFF} indicates the least-significant byte should
* be used to store the data.
* </p>
*
* <p>
* As an example, consider a car painting machine that accepts paint
* instructions as integers. Bit fields can be used to encode this:
* </p>
*
* <pre>
* // blue, green and red are 1 byte values (0-255) stored in the three least
* // significant bytes
* BitField blue = new BitField(0xFF);
* BitField green = new BitField(0xFF00);
* BitField red = new BitField(0xFF0000);
*
* // anyColor is a flag triggered if any color is used
* BitField anyColor = new BitField(0xFFFFFF);
*
* // isMetallic is a single bit flag
* BitField isMetallic = new BitField(0x1000000);
* </pre>
*
* <p>
* Using these {@code BitField} instances, a paint instruction can be encoded
* into an integer:
* </p>
*
* <pre>
* int paintInstruction = 0;
* paintInstruction = red.setValue(paintInstruction, 35);
* paintInstruction = green.setValue(paintInstruction, 100);
* paintInstruction = blue.setValue(paintInstruction, 255);
* </pre>
*
* <p>
* Flags and data can be retrieved from the integer:
* </p>
*
* <pre>
* // Prints true if red, green or blue is non-zero
* System.out.println(anyColor.isSet(paintInstruction)); // prints true
*
* // Prints value of red, green and blue
* System.out.println(red.getValue(paintInstruction)); // prints 35
* System.out.println(green.getValue(paintInstruction)); // prints 100
* System.out.println(blue.getValue(paintInstruction)); // prints 255
*
* // Prints true if isMetallic was set
* System.out.println(isMetallic.isSet(paintInstruction)); // prints false
* </pre>
*
* @since 2.0
*/
public class BitField {
private final int _mask;
private final int _shift_count;
/**
* <p>
* Creates a BitField instance.
* </p>
*
* @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;
_shift_count = mask == 0 ? 0 : Integer.numberOfTrailingZeros(mask);
}
/**
* <p>
* Obtains the value for the specified BitField, appropriately shifted right.
* </p>
*
* <p>
* 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).
* </p>
*
* @see #setValue(int,int)
* @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;
}
/**
* <p>
* Obtains the value for the specified BitField, appropriately shifted right, as
* a short.
* </p>
*
* <p>
* 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).
* </p>
*
* @see #setShortValue(short,short)
* @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);
}
/**
* <p>
* Obtains the value for the specified BitField, unshifted.
* </p>
*
* @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;
}
/**
* <p>
* Obtains the value for the specified BitField, unshifted.
* </p>
*
* @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);
}
/**
* <p>
* Returns whether the field is set or not.
* </p>
*
* <p>
* 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.
* </p>
*
* @param holder the int data containing the bits we're interested in
* @return {@code true} if any of the bits are set, else {@code false}
*/
public boolean isSet(final int holder) {
return (holder & _mask) != 0;
}
/**
* <p>
* Returns whether all of the bits are set or not.
* </p>
*
* <p>
* This is a stricter test than {@link #isSet(int)}, in that all of the bits in
* a multi-bit set must be set for this method to return {@code true}.
* </p>
*
* @param holder the int data containing the bits we're interested in
* @return {@code true} if all of the bits are set, else {@code false}
*/
public boolean isAllSet(final int holder) {
return (holder & _mask) == _mask;
}
/**
* <p>
* Replaces the bits with new values.
* </p>
*
* @see #getValue(int)
* @param holder the int 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 int setValue(final int holder, final int value) {
return (holder & ~_mask) | ((value << _shift_count) & _mask);
}
/**
* <p>
* Replaces the bits with new values.
* </p>
*
* @see #getShortValue(short)
* @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);
}
/**
* <p>
* Clears the bits.
* </p>
*
* @param holder the int data containing the bits we're interested in
* @return the value of holder with the specified bits cleared (set to
* {@code 0})
*/
public int clear(final int holder) {
return holder & ~_mask;
}
/**
* <p>
* Clears the bits.
* </p>
*
* @param holder the short data containing the bits we're interested in
* @return the value of holder with the specified bits cleared (set to
* {@code 0})
*/
public short clearShort(final short holder) {
return (short) clear(holder);
}
/**
* <p>
* Clears the bits.
* </p>
*
* @param holder the byte data containing the bits we're interested in
*
* @return the value of holder with the specified bits cleared (set to
* {@code 0})
*/
public byte clearByte(final byte holder) {
return (byte) clear(holder);
}
/**
* <p>
* Sets the bits.
* </p>
*
* @param holder the int data containing the bits we're interested in
* @return the value of holder with the specified bits set to {@code 1}
*/
public int set(final int holder) {
return holder | _mask;
}
/**
* <p>
* Sets the bits.
* </p>
*
* @param holder the short data containing the bits we're interested in
* @return the value of holder with the specified bits set to {@code 1}
*/
public short setShort(final short holder) {
return (short) set(holder);
}
/**
* <p>
* Sets the bits.
* </p>
*
* @param holder the byte data containing the bits we're interested in
*
* @return the value of holder with the specified bits set to {@code 1}
*/
public byte setByte(final byte holder) {
return (byte) set(holder);
}
/**
* <p>
* Sets a boolean BitField.
* </p>
*
* @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);
}
/**
* <p>
* Sets a boolean BitField.
* </p>
*
* @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);
}
/**
* <p>
* Sets a boolean BitField.
* </p>
*
* @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);
}
}