Trait bitpacking::BitPacker

pub trait BitPacker {
    type DataType;

    const BLOCK_LEN: usize;

    fn compress(
        decompressed: &[u32], 
        compressed: &mut [u8], 
        num_bits: u8
    ) -> usize;
    fn compress_sorted(
        initial: u32, 
        decompressed: &[u32], 
        compressed: &mut [u8], 
        num_bits: u8
    ) -> usize;
    fn decompress_to<Output: FnMut(Self::DataType)>(
        compressed: &[u8], 
        output: Output, 
        num_bits: u8
    ) -> usize;
    fn decompress(
        compressed: &[u8], 
        decompressed: &mut [u32], 
        num_bits: u8
    ) -> usize;
    fn decompress_sorted(
        initial: u32, 
        compressed: &[u8], 
        decompressed: &mut [u32], 
        num_bits: u8
    ) -> usize;
    fn num_bits(decompressed: &[u32]) -> u8;
    fn num_bits_sorted(initial: u32, decompressed: &[u32]) -> u8;

    fn compressed_block_size(num_bits: u8) -> usize { ... }
}

Associated Types

type DataType

Type of the register used by the BitPacker.

Associated Constants

const BLOCK_LEN: usize

Integers are compressed in pack of BLOCK_LEN u32-integers.

BLOCK_LEN is required to be a power of 2, greater than 8. A high BLOCK_LEN may negatively impact the compression rate.

Indeed all integers of a given block will take as many bits as the most significant bit of the largest integer.

Required Methods

fn compress(decompressed: &[u32], compressed: &mut [u8], num_bits: u8) -> usize

Compress a block of u32

Assumes that the integers are all lower than 2^num_bits. The result is undefined if they are larger.

Returns the amount of bytes of the compressed block.

Panics

Panics if the compressed destination array is assumed to be large enough. Panics if decompressed length is not exactly the BLOCK_LEN.

fn compress_sorted(
    initial: u32,
    decompressed: &[u32],
    compressed: &mut [u8],
    num_bits: u8
) -> usize

Delta encode and compressed the decompressed array.

Assumes that the decompressed array is sorted. The first element will assume the previous element is initial.

Returns the amount of bytes of the compressed block.

Panics

Panics if the compressed array is too short. Panics if the decompressed array is not exactly the BLOCK_LEN.

fn decompress_to<Output: FnMut(Self::DataType)>(
    compressed: &[u8],
    output: Output,
    num_bits: u8
) -> usize

Decompresses the compressed array and streams registers full of u32 to the output functions.

fn decompress(
    compressed: &[u8],
    decompressed: &mut [u32],
    num_bits: u8
) -> usize

fn decompress_sorted(
    initial: u32,
    compressed: &[u8],
    decompressed: &mut [u32],
    num_bits: u8
) -> usize

fn num_bits(decompressed: &[u32]) -> u8

Returns the minimum number of bits used to represent all integers in the decompressed array.

fn num_bits_sorted(initial: u32, decompressed: &[u32]) -> u8

Returns the minimum number of bits used to represent all the deltas in the decompressed array.

Provided Methods

fn compressed_block_size(num_bits: u8) -> usize

Returns the size of a compressed block.

Implementors

• impl BitPacker for ScalarBitPacker type DataType = u32;
• impl BitPacker for SSE3BitPacker type DataType = DataType;