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author | Mattias Andrée <maandree@operamail.com> | 2014-01-24 13:25:18 +0100 |
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committer | Mattias Andrée <maandree@operamail.com> | 2014-01-24 13:25:18 +0100 |
commit | 3acfd666b159b61d7693edbc4d0e26b1a1ea70bc (patch) | |
tree | f37ee291081c641a2650403919163045cd5b0a93 | |
parent | typo (diff) | |
download | algorithms-and-data-structures-3acfd666b159b61d7693edbc4d0e26b1a1ea70bc.tar.gz algorithms-and-data-structures-3acfd666b159b61d7693edbc4d0e26b1a1ea70bc.tar.bz2 algorithms-and-data-structures-3acfd666b159b61d7693edbc4d0e26b1a1ea70bc.tar.xz |
calculating next power of two
Signed-off-by: Mattias Andrée <maandree@operamail.com>
-rw-r--r-- | src/algorithms/bits/Powers.java | 48 |
1 files changed, 47 insertions, 1 deletions
diff --git a/src/algorithms/bits/Powers.java b/src/algorithms/bits/Powers.java index 84c9399..2238bcd 100644 --- a/src/algorithms/bits/Powers.java +++ b/src/algorithms/bits/Powers.java @@ -22,7 +22,9 @@ package algorithms.bits; */ public class Powers { -£>for T in char byte short int long; do +£<for T_S in char_2 byte_1 short_2 int_4 long_8; do + T=${T_S%_*} +£>S=${T_S#*_} /** * Compute whether an integer is a power of two, * note that zero is indeed not a power of two @@ -35,6 +37,50 @@ public class Powers return (value & (value - 1)) == 0; /* The left hand side clears the least significant bit set */ /* Or alternatively: (value & -value) == value */ } + + /** + * Computes the nearest, but higher, power of two, + * independently of whether the current value is + * a power of two or not + * + * @param value The current value + * @return The next power of two + */ + public static £{T} nextPowerOf2(£{T} value) + { + value |= value >> 1; + value |= value >> 2; + value |= value >> 4; +£>(( S > 1)) && + value |= value >> 8; +£>(( S > 2)) && + value |= value >> 16; +£>(( S > 4)) && + value |= value >> 32; + return (£{T})(value + 1); + } + + /** + * Computes the nearest, but higher, power of two, + * but only if the current value is not a power of two + * + * @param value The current value + * @return The next power of two + */ + public static £{T} toPowerOf2(£{T} value) + { + value -= 1; + value |= value >>> 1; + value |= value >>> 2; + value |= value >>> 4; +£>(( S > 1)) && + value |= value >>> 8; +£>(( S > 2)) && + value |= value >>> 16; +£>(( S > 4)) && + value |= value >>> 32; + return (£{T})(value + 1); + } £>done } |