com.android.dx.util

Class Bits

java.lang.Object

com.android.dx.util.Bits

public final class Bits
extends java.lang.Object

Utilities for treating int[]s as bit sets.

Method Summary

Modifier and Type	Method and Description
static boolean	anyInRange(int[] bits, int start, int end) Returns whether any bits are set to true in the specified range.
static int	bitCount(int[] bits) Gets the number of bits set to true in the given bit set.
static void	clear(int[] bits, int idx) Sets the given bit to false.
static int	findFirst(int[] bits, int idx) Finds the lowest-order bit set at or after the given index in the given bit set.
static int	findFirst(int value, int idx) Finds the lowest-order bit set at or after the given index in the given int.
static boolean	get(int[] bits, int idx) Gets the value of the bit at the given index.
static int	getMax(int[] bits) Gets the maximum index (exclusive) for the given bit set.
static boolean	isEmpty(int[] bits) Returns whether or not the given bit set is empty, that is, whether no bit is set to true.
static int[]	makeBitSet(int max) Constructs a bit set to contain bits up to the given index (exclusive).
static void	or(int[] a, int[] b) Ors bit array b into bit array a.
static void	set(int[] bits, int idx) Sets the given bit to true.
static void	set(int[] bits, int idx, boolean value) Sets the given bit to the given value.
static java.lang.String	toHuman(int[] bits)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Method Detail

makeBitSet

public static int[] makeBitSet(int max)

Constructs a bit set to contain bits up to the given index (exclusive).

Parameters:

max - >= 0; the maximum bit index (exclusive)

Returns:

non-null; an appropriately-constructed instance

getMax

public static int getMax(int[] bits)

Gets the maximum index (exclusive) for the given bit set.

Parameters:

bits - non-null; bit set in question

Returns:

>= 0; the maximum index (exclusive) that may be set

get

public static boolean get(int[] bits,
                          int idx)

Gets the value of the bit at the given index.

Parameters:

bits - non-null; bit set to operate on

idx - >= 0, < getMax(set); which bit

Returns:

the value of the indicated bit

set

public static void set(int[] bits,
                       int idx,
                       boolean value)

Sets the given bit to the given value.

Parameters:

bits - non-null; bit set to operate on

idx - >= 0, < getMax(set); which bit

value - the new value for the bit

set

public static void set(int[] bits,
                       int idx)

Sets the given bit to true.

Parameters:

bits - non-null; bit set to operate on

idx - >= 0, < getMax(set); which bit

clear

public static void clear(int[] bits,
                         int idx)

Sets the given bit to false.

Parameters:

bits - non-null; bit set to operate on

idx - >= 0, < getMax(set); which bit

isEmpty

public static boolean isEmpty(int[] bits)

Returns whether or not the given bit set is empty, that is, whether no bit is set to true.

Parameters:

bits - non-null; bit set to operate on

Returns:

true iff all bits are false

bitCount

public static int bitCount(int[] bits)

Gets the number of bits set to true in the given bit set.

Parameters:

bits - non-null; bit set to operate on

Returns:

>= 0; the bit count (aka population count) of the set

anyInRange

public static boolean anyInRange(int[] bits,
                                 int start,
                                 int end)

Returns whether any bits are set to true in the specified range.

Parameters:

bits - non-null; bit set to operate on

start - >= 0; index of the first bit in the range (inclusive)

end - >= 0; index of the last bit in the range (exclusive)

Returns:

true if any bit is set to true in the indicated range

findFirst

public static int findFirst(int[] bits,
                            int idx)

Finds the lowest-order bit set at or after the given index in the given bit set.

Parameters:

bits - non-null; bit set to operate on

idx - >= 0; minimum index to return

Returns:

>= -1; lowest-order bit set at or after idx, or -1 if there is no appropriate bit index to return

findFirst

public static int findFirst(int value,
                            int idx)

Finds the lowest-order bit set at or after the given index in the given int.

Parameters:

value - the value in question

idx - 0..31 the minimum bit index to return

Returns:

>= -1; lowest-order bit set at or after idx, or -1 if there is no appropriate bit index to return

or

public static void or(int[] a,
                      int[] b)

Ors bit array b into bit array a. a.length must be greater than or equal to b.length.

Parameters:

a - non-null; int array to be ored with other argument. This argument is modified.

b - non-null; int array to be ored into a. This argument is not modified.

toHuman

public static java.lang.String toHuman(int[] bits)