Implementation of a bit map of any size, together with static methods to manipulate int, byte and byte[] values as bit maps
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/**
* Implementation of a bit map of any size, together with static methods to
* manipulate int, byte and byte[] values as bit maps.
*
* @author Fred Toussi (fredt@users dot sourceforge.net)
* @version 1.9.0
* @since 1.8.0
*/
public class BitMap {
int defaultCapacity;
int capacity;
int[] map;
int limitPos;
public BitMap(int initialCapacity) {
int words = initialCapacity / 32;
if (initialCapacity % 32 != 0) {
words++;
}
defaultCapacity = capacity = words * 32;
map = new int[words];
limitPos = 0;
}
public int size() {
return limitPos;
}
public void setSize(int size) {
limitPos = size;
}
/**
* Resets to blank with original capacity
*/
public void reset() {
map = new int[defaultCapacity / 32];
capacity = defaultCapacity;
limitPos = 0;
}
/**
* Sets pos and returns old value
*/
public int set(int pos) {
while (pos >= capacity) {
doubleCapacity();
}
if (pos >= limitPos) {
limitPos = pos + 1;
}
int windex = pos >> 5;
int mask = 0x80000000 >>> (pos & 0x1F);
int word = map[windex];
int result = (word & mask) == 0 ? 0
: 1;
map[windex] = (word | mask);
return result;
}
/**
* Unsets pos and returns old value
*/
public int unset(int pos) {
while (pos >= capacity) {
doubleCapacity();
}
if (pos >= limitPos) {
limitPos = pos + 1;
return 0;
}
int windex = pos >> 5;
int mask = 0x80000000 >>> (pos & 0x1F);
int word = map[windex];
int result = (word & mask) == 0 ? 0
: 1;
mask = ~mask;
map[windex] = (word & mask);
return result;
}
public int get(int pos) {
while (pos >= capacity) {
doubleCapacity();
}
if (pos >= limitPos) {
limitPos = pos + 1;
return 0;
}
int windex = pos >> 5;
int mask = 0x80000000 >>> (pos & 0x1F);
int word = map[windex];
return (word & mask) == 0 ? 0
: 1;
}
public boolean isSet(int pos) {
return get(pos) == 1;
}
public byte[] getBytes() {
byte[] buf = new byte[(limitPos + 7) / 8];
if (buf.length == 0) {
return buf;
}
for (int i = 0; ; ) {
int v = map[i / 4];
buf[i++] = (byte) (v >>> 24);
if (i == buf.length) {
break;
}
buf[i++] = (byte) (v >>> 16);
if (i == buf.length) {
break;
}
buf[i++] = (byte) (v >>> 8);
if (i == buf.length) {
break;
}
buf[i++] = (byte) v;
if (i == buf.length) {
break;
}
}
return buf;
}
private void doubleCapacity() {
int[] newmap = new int[map.length * 2];
capacity *= 2;
System.arraycopy(map, 0, newmap, 0, map.length);
map = newmap;
}
/**
* copy the byte value into the map at given position (0, 24)
*/
public static int setByte(int map, byte value, int pos) {
int intValue = (value & 0xff) << (24 - pos);
int mask = 0xff000000 >>> pos;
mask = ~mask;
map &= mask;
return (map | intValue);
}
public static int set(int map, int pos) {
int mask = 0x80000000 >>> pos;
return (map | mask);
}
public static byte set(byte map, int pos) {
int mask = 0x00000080 >>> pos;
return (byte) (map | mask);
}
public static int unset(int map, int pos) {
int mask = 0x80000000 >>> pos;
mask = ~mask;
return (map & mask);
}
public static boolean isSet(int map, int pos) {
int mask = 0x80000000 >>> pos;
return (map & mask) == 0 ? false
: true;
}
public static boolean isSet(byte map, int pos) {
int mask = 0x00000080 >>> pos;
return (map & mask) == 0 ? false
: true;
}
public static boolean isSet(byte[] map, int pos) {
int mask = 0x00000080 >>> (pos & 0x07);;
int index = pos / 8;
if (index >= map.length) {
return false;
}
byte b = map[index];
return (b & mask) == 0 ? false
: true;
}
public static void unset(byte[] map, int pos) {
int mask = 0x00000080 >>> (pos & 0x07);
mask = ~mask;
int index = pos / 8;
if (index >= map.length) {
return;
}
byte b = map[index];
map[index] = (byte) (b & mask);
}
public static void set(byte[] map, int pos) {
int mask = 0x00000080 >>> (pos & 0x07);
int index = pos / 8;
if (index >= map.length) {
return;
}
byte b = map[index];
map[index] = (byte) (b | mask);
}
/**
* AND count bits from source with map contents starting at pos
*/
public static void and(byte[] map, int pos, byte source, int count) {
int shift = pos & 0x07;
int mask = (source & 0xff) >>> shift;
int innermask = 0xff >> shift;
int index = pos / 8;
if (count < 8) {
innermask = innermask >>> (8 - count);
innermask = innermask << (8 - count);
}
mask &= innermask;
innermask = ~innermask;
if (index >= map.length) {
return;
}
byte b = map[index];
map[index] = (byte) (b & innermask);
b = (byte) (b & mask);
map[index] = (byte) (map[index] | b);
if (shift == 0) {
return;
}
shift = 8 - shift;
if (count > shift) {
mask = ((source & 0xff) << 8) >>> shift;
innermask = 0xff00 >>> shift;
innermask = ~innermask;
b = map[index + 1];
map[index + 1] = (byte) (b & innermask);
b = (byte) (b & mask);
map[index + 1] = (byte) (map[index + 1] | b);
}
}
/**
* OR count bits from source with map contents starting at pos
*/
public static void or(byte[] map, int pos, byte source, int count) {
int shift = pos & 0x07;
int mask = (source & 0xff) >>> shift;
int index = pos / 8;
if (index >= map.length) {
return;
}
byte b = (byte) (map[index] | mask);
map[index] = b;
if (shift == 0) {
return;
}
shift = 8 - shift;
if (count > shift) {
mask = ((source & 0xff) << 8) >>> shift;
b = (byte) (map[index + 1] | mask);
map[index + 1] = b;
}
}
/**
* overlay count bits from source on map contents starting at pos
*/
public static void overlay(byte[] map, int pos, byte source, int count) {
int shift = pos & 0x07;
int mask = (source & 0xff) >>> shift;
int innermask = 0xff >> shift;
int index = pos / 8;
if (count < 8) {
innermask = innermask >>> (8 - count);
innermask = innermask << (8 - count);
}
mask &= innermask;
innermask = ~innermask;
if (index >= map.length) {
return;
}
byte b = map[index];
b = (byte) (b & innermask);
map[index] = (byte) (b | mask);
if (shift == 0) {
return;
}
shift = 8 - shift;
if (count > shift) {
mask = ((source & 0xff) << 8) >>> shift;
innermask = 0xff00 >>> shift;
innermask = ~innermask;
b = map[index + 1];
b = (byte) (b & innermask);
map[index + 1] = (byte) (b | mask);
}
}
public static int compare(byte[] a, byte[] b) {
int shortLength = a.length > b.length ? b.length
: a.length;
for (int i = 0; i < shortLength; i++) {
if (a[i] == b[i]) {
continue;
}
return (((int) a[i]) & 0xff) > (((int) b[i]) & 0xff) ? 1
: -1;
}
if (a.length == b.length) {
return 0;
}
return a.length > b.length ? 1
: -1;
}
public static byte[] and(byte[] a, byte[] b) {
int length = a.length > b.length ? a.length
: b.length;
int shortLength = a.length > b.length ? b.length
: a.length;
byte[] map = new byte[length];
for (int i = 0; i < shortLength; i++) {
map[i] = (byte) (a[i] & b[i]);
}
return map;
}
public static byte[] or(byte[] a, byte[] b) {
int length = a.length > b.length ? a.length
: b.length;
int shortLength = a.length > b.length ? b.length
: a.length;
byte[] map = new byte[length];
if (length != shortLength) {
byte[] source = a.length > b.length ? a
: b;
System.arraycopy(source, shortLength, map, shortLength,
length - shortLength);
}
for (int i = 0; i < shortLength; i++) {
map[i] = (byte) (a[i] | b[i]);
}
return map;
}
public static byte[] xor(byte[] a, byte[] b) {
int length = a.length > b.length ? a.length
: b.length;
int shortLength = a.length > b.length ? b.length
: a.length;
byte[] map = new byte[length];
if (length != shortLength) {
byte[] source = a.length > b.length ? a
: b;
System.arraycopy(source, shortLength, map, shortLength,
length - shortLength);
}
for (int i = 0; i < shortLength; i++) {
map[i] = (byte) (a[i] ^ b[i]);
}
return map;
}
public static byte[] not(byte[] a) {
byte[] map = new byte[a.length];
for (int i = 0; i < a.length; i++) {
map[i] = (byte) ~a[i];
}
return map;
}
public static boolean hasAnyBitSet(byte[] map) {
for (int i = 0; i < map.length; i++) {
if (map[i] != 0) {
return true;
}
}
return false;
}
public static byte[] leftShift(byte[] map, int shiftBits) {
byte[] newMap = new byte[map.length];
int shiftBytes = shiftBits / 8;
if (shiftBytes >= map.length) {
return newMap;
}
shiftBits = shiftBits % 8;
if (shiftBits == 0) {
for (int i = 0, j = shiftBytes; j < map.length; i++, j++) {
newMap[i] = map[j];
}
} else {
for (int i = 0, j = shiftBytes; j < map.length; i++, j++) {
int shifted = (map[j] & 0xff) << shiftBits;
newMap[i] = (byte) shifted;
if (i > 0) {
newMap[i - 1] |= (byte) (shifted >>> 8);
}
}
}
return newMap;
}
}
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