diff options
Diffstat (limited to 'src/java/com/jogamp/common')
| -rw-r--r-- | src/java/com/jogamp/common/util/Bitfield.java | 80 | ||||
| -rw-r--r-- | src/java/com/jogamp/common/util/IntBitfield.java | 6 |
2 files changed, 62 insertions, 24 deletions
diff --git a/src/java/com/jogamp/common/util/Bitfield.java b/src/java/com/jogamp/common/util/Bitfield.java index f7eaeb0..d7ada5a 100644 --- a/src/java/com/jogamp/common/util/Bitfield.java +++ b/src/java/com/jogamp/common/util/Bitfield.java @@ -34,26 +34,58 @@ import jogamp.common.util.SyncedBitfield; * @since 2.3.2 */ public interface Bitfield { + /** Maximum 32 bit Unsigned Integer Value: {@code 0xffffffff} == {@value}. */ + public static final int UNSIGNED_INT_MAX_VALUE = 0xffffffff; + /** * Bit operation utilities (static). */ public static class Util { /** + * Returns the 32 bit mask of n-bits, i.e. n low order 1’s. + * <p> + * Implementation handles n == 32. + * </p> + * @throws IndexOutOfBoundsException if {@code b} is out of bounds, i.e. > 32 + */ + public static int getBitMask(final int n) { + if( 32 > n ) { + return ( 1 << n ) - 1; + } else if ( 32 == n ) { + return UNSIGNED_INT_MAX_VALUE; + } else { + throw new IndexOutOfBoundsException("n <= 32 expected, is "+n); + } + } + + /** * Returns the number of set bits within given 32bit integer in O(1) - * using <i>HAKEM Bit Count</i>: + * using a <i>HAKEM 169 Bit Count</i> inspired implementation: * <pre> * http://www.inwap.com/pdp10/hbaker/hakmem/hakmem.html * http://home.pipeline.com/~hbaker1/hakmem/hacks.html#item169 * http://tekpool.wordpress.com/category/bit-count/ + * http://www.hackersdelight.org/ * </pre> */ - public static final int getBitCount(final int n) { + public static final int bitCount(int n) { // Note: Original used 'unsigned int', // hence we use the unsigned right-shift '>>>' - int c = n; - c -= (n >>> 1) & 033333333333; - c -= (n >>> 2) & 011111111111; - return ( (c + ( c >>> 3 ) ) & 030707070707 ) % 63; + /** + * Original does not work due to lack of 'unsigned' right-shift and modulo, + * we need 2-complementary solution, i.e. 'signed'. + int c = n; + c -= (n >>> 1) & 033333333333; + c -= (n >>> 2) & 011111111111; + return ( (c + ( c >>> 3 ) ) & 030707070707 ) & 0x3f; // % 63 + */ + // Hackers Delight, Figure 5-2, pop1 of pop.c.txt + n = n - ((n >>> 1) & 0x55555555); + n = (n & 0x33333333) + ((n >>> 2) & 0x33333333); + n = (n + (n >>> 4)) & 0x0f0f0f0f; + n = n + (n >>> 8); + n = n + (n >>> 16); + return n & 0x3f; } } /** @@ -84,12 +116,18 @@ public interface Bitfield { /** * Returns the storage size in bit units, e.g. 32 bit for implementations using one {@code int} field. */ - int getStorageBitSize(); + int size(); + + + /** + * Set all bits of this bitfield to the given value {@code bit}. + */ + void clearField(final boolean bit); /** * Returns {@code length} bits from this storage, * starting with the lowest bit from the storage position {@code lowBitnum}. - * @param lowBitnum storage bit position of the lowest bit, restricted to [0..{@link #getStorageBitSize()}-{@code length}]. + * @param lowBitnum storage bit position of the lowest bit, restricted to [0..{@link #size()}-{@code length}]. * @param length number of bits to read, constrained to [0..32]. * @throws IndexOutOfBoundsException if {@code rightBitnum} is out of bounds * @see #put32(int, int, int) @@ -99,8 +137,8 @@ public interface Bitfield { /** * Puts {@code length} bits of given {@code data} into this storage, * starting w/ the lowest bit to the storage position {@code lowBitnum}. - * @param lowBitnum storage bit position of the lowest bit, restricted to [0..{@link #getStorageBitSize()}-{@code length}]. - * @param length number of bits to read, constrained to [0..32]. + * @param lowBitnum storage bit position of the lowest bit, restricted to [0..{@link #size()}-{@code length}]. + * @param length number of bits to write, constrained to [0..32]. * @param data the actual bits to be put into this storage * @throws IndexOutOfBoundsException if {@code rightBitnum} is out of bounds * @see #get32(int, int) @@ -114,8 +152,8 @@ public interface Bitfield { * Implementation shall operate as if invoking {@link #get32(int, int)} * and then {@link #put32(int, int, int)} sequentially. * </p> - * @param srcLowBitnum source bit number, restricted to [0..{@link #getStorageBitSize()}-1]. - * @param dstLowBitnum destination bit number, restricted to [0..{@link #getStorageBitSize()}-1]. + * @param srcLowBitnum source bit number, restricted to [0..{@link #size()}-1]. + * @param dstLowBitnum destination bit number, restricted to [0..{@link #size()}-1]. * @throws IndexOutOfBoundsException if {@code bitnum} is out of bounds * @see #get32(int, int) * @see #put32(int, int, int) @@ -124,7 +162,7 @@ public interface Bitfield { /** * Return <code>true</code> if the bit at position <code>bitnum</code> is set, otherwise <code>false</code>. - * @param bitnum bit number, restricted to [0..{@link #getStorageBitSize()}-1]. + * @param bitnum bit number, restricted to [0..{@link #size()}-1]. * @throws IndexOutOfBoundsException if {@code bitnum} is out of bounds */ boolean get(final int bitnum) throws IndexOutOfBoundsException; @@ -132,21 +170,21 @@ public interface Bitfield { /** * Set or clear the bit at position <code>bitnum</code> according to <code>bit</code> * and return the previous value. - * @param bitnum bit number, restricted to [0..{@link #getStorageBitSize()}-1]. + * @param bitnum bit number, restricted to [0..{@link #size()}-1]. * @throws IndexOutOfBoundsException if {@code bitnum} is out of bounds */ void put(final int bitnum, final boolean bit) throws IndexOutOfBoundsException; /** * Set the bit at position <code>bitnum</code> according to <code>bit</code>. - * @param bitnum bit number, restricted to [0..{@link #getStorageBitSize()}-1]. + * @param bitnum bit number, restricted to [0..{@link #size()}-1]. * @throws IndexOutOfBoundsException if {@code bitnum} is out of bounds */ void set(final int bitnum) throws IndexOutOfBoundsException; /** * Clear the bit at position <code>bitnum</code> according to <code>bit</code>. - * @param bitnum bit number, restricted to [0..{@link #getStorageBitSize()}-1]. + * @param bitnum bit number, restricted to [0..{@link #size()}-1]. * @throws IndexOutOfBoundsException if {@code bitnum} is out of bounds */ void clear(final int bitnum) throws IndexOutOfBoundsException; @@ -154,17 +192,17 @@ public interface Bitfield { /** * Copies the bit at position {@code srcBitnum} to position {@code dstBitnum} * and returning <code>true</code> if the bit is set, otherwise <code>false</code>. - * @param srcBitnum source bit number, restricted to [0..{@link #getStorageBitSize()}-1]. - * @param dstBitnum destination bit number, restricted to [0..{@link #getStorageBitSize()}-1]. + * @param srcBitnum source bit number, restricted to [0..{@link #size()}-1]. + * @param dstBitnum destination bit number, restricted to [0..{@link #size()}-1]. * @throws IndexOutOfBoundsException if {@code bitnum} is out of bounds */ boolean copy(final int srcBitnum, final int dstBitnum) throws IndexOutOfBoundsException; /** - * Returns the number of set bits within this bitfield. + * Returns the number of one bits within this bitfield. * <p> - * Utilizes {#link {@link Bitfield.Util#getBitCount(int)}}. + * Utilizes {#link {@link Bitfield.Util#bitCount(int)}}. * </p> */ - int getBitCount(); + int bitCount(); } diff --git a/src/java/com/jogamp/common/util/IntBitfield.java b/src/java/com/jogamp/common/util/IntBitfield.java index 3ef5bb7..e7a9d70 100644 --- a/src/java/com/jogamp/common/util/IntBitfield.java +++ b/src/java/com/jogamp/common/util/IntBitfield.java @@ -140,10 +140,10 @@ public class IntBitfield { return prev; } /** - * @deprecated Use {@link Bitfield.Util#getBitCount(int)}. + * @deprecated Use {@link Bitfield.Util#bitCount(int)}. */ public static final int getBitCount(final int n) { - return Bitfield.Util.getBitCount(n); + return Bitfield.Util.bitCount(n); } /** @@ -155,7 +155,7 @@ public class IntBitfield { public long getBitCount() { long c = 0; for(int i = storage.length-1; i>=0; i--) { - c += Bitfield.Util.getBitCount(storage[i]); + c += Bitfield.Util.bitCount(storage[i]); } return c; } |