diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/algorithms/bits/Bits.java | 71 |
1 files changed, 64 insertions, 7 deletions
diff --git a/src/algorithms/bits/Bits.java b/src/algorithms/bits/Bits.java index 87939f7..493e16d 100644 --- a/src/algorithms/bits/Bits.java +++ b/src/algorithms/bits/Bits.java @@ -22,27 +22,46 @@ package algorithms.bits; */ public class Bits { -£<function table +£<function ones-table { if [ $1 = 0 ]; then echo -n "${2}, " else level=$(( $1 - 1 )) - table $level $(( $2 + 0 )) - table $level $(( $2 + 1 )) - table $level $(( $2 + 1 )) - table $level $(( $2 + 2 )) + ones-table $level $(( $2 + 0 )) + ones-table $level $(( $2 + 1 )) + ones-table $level $(( $2 + 1 )) + ones-table $level $(( $2 + 2 )) fi £>} /** * Lookup table for the number of set bits in a byte */ - private static byte[] ONES_TABLE_256 = { £(table 4 0) }; + private static byte[] ONES_TABLE_256 = { £(ones-table 4 0) }; /* ONES_TABLE_256[0] = 0; * for (int i = 0; i < 256; i++) * ONES_TABLE_256[i] = (i & 1) + ONES_TABLE_256[i / 2]; */ + + +£<function parity-table + { + if [ $1 = 0 ]; then + echo -n "${2}, " + else + level=$(( $1 - 1 )) + parity-table $level $(( $2 ^ 0 )) + parity-table $level $(( $2 ^ 1 )) + parity-table $level $(( $2 ^ 1 )) + parity-table $level $(( $2 ^ 0 )) + fi +£>} + + /** + * Lookup table for the parity of the bits in a byte + */ + private static byte[] PARITY_TABLE_256 = { £(parity-table 4 0) }; £<for T_S in char_2 byte_1 short_2 int_4 long_8; do @@ -242,7 +261,7 @@ public class Bits } /** - * Compute the parity of all bits in an integer + * Compute the parity of all bits in an integer, naïve version * * @param value The interger * @return The parity @@ -257,6 +276,44 @@ public class Bits } return rc; } + + /** + * Compute the parity of all bits in an integer, parallel version + * + * @param value The interger + * @return The parity + */ + public static £{T} parity_parallel(£{T} value) + { +£>(( $S > 4 )) && + value ^= value >> 32; +£>(( $S > 2 )) && + value ^= value >> 16; +£>(( $S > 1 )) && + value ^= value >> 8; + value ^= value >> 4; + value ^= value >> 3; + value ^= value >> 2; + value ^= value >> 1; + return value & 1; + } + + /** + * Compute the parity of all bits in an integer, partial lookup table version + * + * @param value The interger + * @return The parity + */ + public static char parity_table(£{T} value) + { +£>(( $S > 4 )) && + value ^= value >> 32; +£>(( $S > 2 )) && + value ^= value >> 16; +£>(( $S > 1 )) && + value ^= value >> 8; + return PARITY_TABLE_256[rc]; + } £>done } |