Java Utililty Methods Bit Count

List of utility methods to do Bit Count

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Description

The list of methods to do Bit Count are organized into topic(s).

Method

intbitLength(int value)
bit Length 
return Integer.SIZE - Integer.numberOfLeadingZeros(value);
intbitSizeForSignedValue(final int value)
bit Size For Signed Value 
if (value > 0) {
    return 33 - Integer.numberOfLeadingZeros(value);
} else if (value == 0) {
    return 1;
} else {
    return 33 - Integer.numberOfLeadingZeros(-value - 1);
intbitSizeForUnsignedValue(final int value)
bit Size For Unsigned Value 
if (value > 0) {
    return 32 - Integer.numberOfLeadingZeros(value);
} else {
    if (value == 0) {
        return 1;
    } else {
        throw new IllegalArgumentException("unsigned value [" + value + "] must be >= 0");
intcountBits(long v)
count Bits 
int count = 0;
for (; v > 0; v = v / 2) {
    ++count;
return count;
intcountBits(byte num)
count Bits 
int count = 0;
for (int i = 0; i < 8; i++) {
    if ((num & 1) == 1) 
        count++;
    num = (byte) (num >>> 1); 
return count;
intcountBits(final int intValue)
Counts the number of 1-Bits in a 32-bit int value and uses a "divide-and-conquer" strategy. 
final byte const16 = 16;
final byte const3F = 0x0000003F;
final int const33 = 0x33333333;
final int const55 = 0x55555555;
final int const0F = 0x0F0F0F0F;
int result = intValue;
result -= ((result >>> 1) & const55);
result = (result & const33) + ((result >>> 2) & const33);
...
intcountBits(int i)
Count the number of non-zero bits of a integer 
i = (((i & 0xAAAAAAAA) >>> 1) + (i & 0x55555555));
i = (((i & 0xCCCCCCCC) >>> 2) + (i & 0x33333333));
i = (((i & 0xF0F0F0F0) >>> 4) + (i & 0x0F0F0F0F));
i = (((i & 0xFF00FF00) >>> 8) + (i & 0x00FF00FF));
i = (((i & 0xFFFF0000) >>> 16) + (i & 0x0000FFFF));
return i;
intcountBits(int mask)
count Bits 
int count = 0;
for (int index = 0; index < 32; index++) {
    if ((mask & 0x1) != 0) {
        count++;
    mask = mask >>> 1;
return count;
...
intcountBits(int n)
A magic utility method that happens to return the number of bits that are set to '1' in the given number. 
int m = n - ((n >> 1) & 033333333333) - ((n >> 2) & 011111111111);
return ((m + (m >> 3)) & 030707070707) % 63;
intcountBits(int x)
Count the bits in an int 
int n = 0;
while (x != 0) {
    if ((x & 1) != 0)
        n++;
    x >>>= 1;
return n;