File	Doc	Category	Size	Date	Package
Bits.java	API Doc	Android 1.5 API	7121	Wed May 06 22:41:02 BST 2009	com.android.dx.util

Bits

• java.lang.Object

Fields Summary

Constructors Summary
private Bits() This class is uninstantiable. // This space intentionally left blank.

Methods Summary
public static boolean	anyInRange(int[] bits, int start, int end) Returns whether any bits are set to true in the specified range. param bits non-null; bit set to operate on param start >= 0; index of the first bit in the range (inclusive) param end >= 0; index of the last bit in the range (exclusive) return true if any bit is set to true in the indicated range int idx = findFirst(bits, start); return (idx >= 0) && (idx < end);
public static int	bitCount(int[] bits) Gets the number of bits set to true in the given bit set. param bits non-null; bit set to operate on return >= 0; the bit count (aka population count) of the set int len = bits.length; int count = 0; for (int i = 0; i < len; i++) { count += Integer.bitCount(bits[i]); } return count;
public static void	clear(int[] bits, int idx) Sets the given bit to false. param bits non-null; bit set to operate on param idx >= 0, < getMax(set); which bit int arrayIdx = idx >> 5; int bit = 1 << (idx & 0x1f); bits[arrayIdx] &= ~bit;
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. param bits non-null; bit set to operate on param idx >= 0; minimum index to return return >= -1; lowest-order bit set at or after idx, or -1 if there is no appropriate bit index to return int len = bits.length; int minBit = idx & 0x1f; for (int arrayIdx = idx >> 5; arrayIdx < len; arrayIdx++) { int word = bits[arrayIdx]; if (word != 0) { int bitIdx = findFirst(word, minBit); if (bitIdx >= 0) { return (arrayIdx << 5) + bitIdx; } } minBit = 0; } return -1;
public static int	findFirst(int value, int idx) Finds the lowest-order bit set at or after the given index in the given int. param value the value in question param idx 0..31 the minimum bit index to return return >= -1; lowest-order bit set at or after idx, or -1 if there is no appropriate bit index to return value &= ~((1 << idx) - 1); // Mask off too-low bits. int result = Integer.numberOfTrailingZeros(value); return (result == 32) ? -1 : result;
public static boolean	get(int[] bits, int idx) Gets the value of the bit at the given index. param bits non-null; bit set to operate on param idx >= 0, < getMax(set); which bit return the value of the indicated bit int arrayIdx = idx >> 5; int bit = 1 << (idx & 0x1f); return (bits[arrayIdx] & bit) != 0;
public static int	getMax(int[] bits) Gets the maximum index (exclusive) for the given bit set. param bits non-null; bit set in question return >= 0; the maximum index (exclusive) that may be set return bits.length * 0x20;
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. param bits non-null; bit set to operate on return true iff all bits are false int len = bits.length; for (int i = 0; i < len; i++) { if (bits[i] != 0) { return false; } } return true;
public static int[]	makeBitSet(int max) Constructs a bit set to contain bits up to the given index (exclusive). param max >= 0; the maximum bit index (exclusive) return non-null; an appropriately-constructed instance int size = (max + 0x1f) >> 5; return new int[size];
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. param a non-null; int array to be ored with other argument. This argument is modified. param b non-null; int array to be ored into a. This argument is not modified. for (int i = 0; i < b.length; i++) { a[i] |= b[i]; }
public static void	set(int[] bits, int idx, boolean value) Sets the given bit to the given value. param bits non-null; bit set to operate on param idx >= 0, < getMax(set); which bit param value the new value for the bit int arrayIdx = idx >> 5; int bit = 1 << (idx & 0x1f); if (value) { bits[arrayIdx] |= bit; } else { bits[arrayIdx] &= ~bit; }
public static void	set(int[] bits, int idx) Sets the given bit to true. param bits non-null; bit set to operate on param idx >= 0, < getMax(set); which bit int arrayIdx = idx >> 5; int bit = 1 << (idx & 0x1f); bits[arrayIdx] |= bit;
public static java.lang.String	toHuman(int[] bits) StringBuilder sb = new StringBuilder(); boolean needsComma = false; sb.append('{"); int bitsLength = 32 * bits.length; for (int i = 0; i < bitsLength; i++) { if (Bits.get(bits, i)) { if (needsComma) { sb.append(',"); } needsComma = true; sb.append(i); } } sb.append('}"); return sb.toString();