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| author | Mattias Andrée <maandree@operamail.com> | 2014-01-20 05:28:42 +0100 |
|---|---|---|
| committer | Mattias Andrée <maandree@operamail.com> | 2014-01-20 05:28:42 +0100 |
| commit | c90e3520eaf46069e5ff09acfcaa6094c24edb7f (patch) | |
| tree | b91a0bd9e4312ecddfb16fe7bfd904a1a6639416 /src | |
| parent | m (diff) | |
| download | algorithms-and-data-structures-c90e3520eaf46069e5ff09acfcaa6094c24edb7f.tar.gz algorithms-and-data-structures-c90e3520eaf46069e5ff09acfcaa6094c24edb7f.tar.bz2 algorithms-and-data-structures-c90e3520eaf46069e5ff09acfcaa6094c24edb7f.tar.xz | |
more bit counting
Signed-off-by: Mattias Andrée <maandree@operamail.com>
Diffstat (limited to 'src')
| -rw-r--r-- | src/algorithms/bits/Bits.java | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/src/algorithms/bits/Bits.java b/src/algorithms/bits/Bits.java index 0357199..abe156a 100644 --- a/src/algorithms/bits/Bits.java +++ b/src/algorithms/bits/Bits.java @@ -138,6 +138,88 @@ public class Bits return (byte)((byte)(£(_ 0) + £(_ 8)) + (byte)(£(_ 16) + £(_ 24))); /* In C you can split the value by getting the address of the value and cast the pointer to char* */ } + + /** + * Calculate the number of set bits in an integer, 64-bits instructions version + * + * @param value The integer + * @return The number of set bits + */ + public static long ones_64bits(£{T} value) + { + long v = value, rc; +£>(( $S > 1 )) && + if ((v & (1L << 14L) - 1L) == v) + { + rc = (v * 0x200040008001L & 0x111111111111111L) % 0xF; + } +£>if (( $S >= 2 )); then + else +£>(( $S > 3 )) && + if ((v & (1L << 24L) - 1L) == v) + { + rc = ((v & 0xFFF) * 0x1001001001001L & 0x84210842108421L) % 0x1F; + rc += (((v & 0XFFF000) >> 12) * 0x1001001001001L & 0x84210842108421L) % 0x1F; + } +£>if (( $S > 3 )); then + else +£>(( $S > 4 )) && + if ((v & (1L << 32L) - 1L) == v) + { + rc = ((v & 0xFFF) * 0x1001001001001L & 0x84210842108421L) % 0x1F; + rc += (((v & 0xFFF000) >> 12) * 0x1001001001001L & 0x84210842108421L) % 0x1F; + rc += ((v >> 24) * 0x1001001001001L & 0x84210842108421L) % 0x1F; + } +£>if (( $S > 4 )); then + else + { + rc = ones_64bits(v & (1L << 32L) - 1L); + rc += ones_64bits(v >>> 32); + } +£>fi;fi;fi + return rc; + } + + /** + * Calculate the number of set bits in an integer, naïve parallel version + * + * @param value The integer + * @return The number of set bits + */ + public static £{T} ones_parallel(£{T} value) + { + £{T} rc = value; + rc = (£{T})(((rc >> 1) & (£{T})0xAAAAAAAAAAAAAAAAL) + (rc & (£{T})0xAAAAAAAAAAAAAAAAL)); + rc = (£{T})(((rc >> 2) & (£{T})0xCCCCCCCCCCCCCCCCL) + (rc & (£{T})0xCCCCCCCCCCCCCCCCL)); + rc = (£{T})(((rc >> 4) & (£{T})0xF0F0F0F0F0F0F0F0L) + (rc & (£{T})0xF0F0F0F0F0F0F0F0L)); +£>(( $S > 1 )) && + rc = (£{T})(((rc >> 8) & (£{T})0xFF00FF00FF00FF00L) + (rc & (£{T})0xFF00FF00FF00FF00L)); +£>(( $S > 2 )) && + rc = (£{T})(((rc >> 16) & (£{T})0xFFFF0000FFFF0000L) + (rc & (£{T})0xFFFF0000FFFF0000L)); +£>(( $S > 4 )) && + rc = (£{T})(((rc >> 32) & (£{T})0xFFFFFFFF00000000L) + (rc & (£{T})0xFFFFFFFF00000000L)); + return rc; + } + + /** + * Calculate the number of set bits in an integer, optimised parallel version + * + * @param value The integer + * @return The number of set bits + */ + public static £{T} ones_optimised_parallel(£{T} value) + { + £{T} rc = (£{T})(value - ((value >> 1) & (£{T})0x5555555555555555L)); + rc = (£{T})(((rc >> 2) & (£{T})0x3333333333333333L) + (rc & (£{T})0x3333333333333333L)); + rc = (£{T})(((rc >> 4) + rc) & (£{T})0x0F0F0F0F0F0F0F0FL); +£>(( $S > 1 )) && + rc = (£{T})(((rc >> 8) + rc) & (£{T})0x00FF00FF00FF00FFL); +£>(( $S > 2 )) && + rc = (£{T})(((rc >> 16) + rc) & (£{T})0x0000FFFF0000FFFFL); +£>(( $S > 4 )) && + rc = (£{T})(((rc >> 32) + rc) & (£{T})0x00000000FFFFFFFFL); + return rc; + } £>done } |