Crate bit_reverse [−] [src]
This library provides a number of ways to compute the bit reversal of all primitive integers. There are currently 3 different algorithms implemented: Bitwise, Parallel, and Lookup reversal.
use bit_reverse::ParallelReverse; assert_eq!(0xA0u8.swap_bits(), 0x05u8);
This library is very simple to uses just import the crate and the algorithm you want to use.
Then you can call
swap_bits() on any primitive integer. If you want to try a different
algorithm just change the use statement and now your program will use the algorithm instead.
I wouldn't use
BitwiseReverse as it is mainly there for completeness and is strictly inferior
ParallelReverse, which is a Bitwise Parallel Reverse and thus an order of magnitude faster.
For small sizes, <= 16 bits,
LookupReverse is the fastest but it doesn't scale as well as
ParallelReverse this is because
ParallelReverse does a constant number of operations for
every size (assuming your cpu has a hardware byte swap instruction).
LookupReverse needs more
lookups, ANDs, and ORs for each size increase. Thus
ParallelReverse performs a little better
at 32 bits and much better at 64 bits. These runtime characteristics are based on a Intel(R)
Core(TM) i7-4770K CPU @ 3.50GHz.
ParallelReverse both only use a couple of stack variables for their
LookupReverse on the other hand statically allocates 256 u8s or 256 bytes to
do its computations.
LookupReverse's memory cost is shared by all of the types
To link to core instead of STD, disable default features for this library in your Cargo.toml. Cargo choosing features
Computes bit reversal by going bit by bit and setting the reverse position bit for the output.
Computes bit reversal by using lookup table to translate a single byte into its reverse. For multi-byte types, the byte order is swapped to complete the reversal.
Computes bit reversal by using a divide and conquer approach. Pairs of bits are swapped. Then neighboring bit pairs are swapped. Each time swapping the next largest group of bits. This is done until the entire data has been bit reversed.