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| </pre><pre class="rust"><code><span class="doccomment">/*! # Fast Bitpacking algorithms |
| |
| This crate is a **Rust port of [Daniel Lemire's simdcomp C library](https://github.com/lemire/simdcomp)**. |
| It contains different flavor of integers compression via bitpacking : `BitPacker1x`, `BitPacker4x`, and `BitPacker8x`. |
| |
| Each produces different formats, and are incompatible one with another, |
| and requires integers to be encoded in block of different size.. |
| |
| `BitPacker4x` and `BitPacker8x` are designed specifically to leverage `SSE3` |
| and `AVX2` instructions respectively. |
| |
| The library will fallback to a scalar implementation if these instruction |
| sets are not available. For instance : |
| - because your compilation target architecture is not `x86_64` |
| - because the CPU you use is from an older generation |
| |
| I recommend using `BitPacker4x` if you are in doubt. |
| |
| See the [`BitPacker` trait](./trait.BitPacker.html) for example usage. |
| |
| */ |
| |
| </span><span class="attribute">#![allow(unused_unsafe)] |
| #![warn(missing_docs)] |
| |
| </span><span class="kw">use </span>std::marker::Sized; |
| |
| <span class="attribute">#[cfg(test)] |
| #[macro_use] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">mod </span>tests; |
| |
| <span class="attribute">#[macro_use] |
| </span><span class="kw">mod </span>macros; |
| <span class="attribute">#[macro_use] |
| </span><span class="kw">mod </span>macros_simple; |
| |
| <span class="kw">trait </span>Available { |
| <span class="kw">fn </span>available() -> bool; |
| } |
| |
| <span class="kw">trait </span>UnsafeBitPacker { |
| <span class="kw">const </span>BLOCK_LEN: usize; |
| <span class="kw">unsafe fn </span>compress(decompressed: <span class="kw-2">&</span>[u32], compressed: <span class="kw-2">&mut </span>[u8], num_bits: u8) -> usize; |
| <span class="kw">unsafe fn </span>compress_sorted( |
| initial: u32, |
| decompressed: <span class="kw-2">&</span>[u32], |
| compressed: <span class="kw-2">&mut </span>[u8], |
| num_bits: u8, |
| ) -> usize; |
| <span class="kw">unsafe fn </span>decompress(compressed: <span class="kw-2">&</span>[u8], decompressed: <span class="kw-2">&mut </span>[u32], num_bits: u8) -> usize; |
| <span class="kw">unsafe fn </span>decompress_sorted( |
| initial: u32, |
| compressed: <span class="kw-2">&</span>[u8], |
| decompressed: <span class="kw-2">&mut </span>[u32], |
| num_bits: u8, |
| ) -> usize; |
| <span class="kw">unsafe fn </span>num_bits(decompressed: <span class="kw-2">&</span>[u32]) -> u8; |
| <span class="kw">unsafe fn </span>num_bits_sorted(initial: u32, decompressed: <span class="kw-2">&</span>[u32]) -> u8; |
| } |
| |
| <span class="doccomment">/// # Examples without delta-encoding |
| /// ``` |
| /// extern crate bitpacking; |
| /// |
| /// use bitpacking::{BitPacker4x, BitPacker}; |
| /// |
| /// # fn main() { |
| /// # let my_data: Vec<u32> = vec![7, 7, 7, 7, 11, 10, 15, 13, 6, 5, 3, 14, 5, 7, |
| /// # 15, 12, 1, 10, 8, 10, 12, 14, 13, 1, 10, 1, 1, 10, 4, 15, 12, |
| /// # 1, 2, 0, 8, 5, 14, 5, 2, 4, 1, 6, 14, 13, 5, 10, 10, 1, 6, 4, |
| /// # 1, 12, 1, 1, 5, 15, 15, 2, 8, 6, 4, 3, 10, 8, 8, 9, 2, 6, 10, |
| /// # 5, 7, 9, 0, 13, 15, 5, 13, 10, 0, 2, 10, 14, 5, 9, 12, 8, 5, 10, |
| /// # 8, 8, 10, 5, 13, 8, 11, 14, 7, 14, 4, 2, 9, 12, 14, 5, 15, 12, 0, |
| /// # 12, 13, 3, 13, 5, 4, 15, 9, 8, 9, 3, 3, 3, 1, 12, 0, 6, 11, 11, 12, 4]; |
| /// |
| /// let bitpacker = BitPacker4x::new(); |
| /// |
| /// let num_bits: u8 = bitpacker.num_bits(&my_data); |
| /// |
| /// // A block will be take at most 4 bytes per-integers. |
| /// let mut compressed = vec![0u8; 4 * BitPacker4x::BLOCK_LEN]; |
| /// |
| /// # assert_eq!(num_bits, 4); |
| /// let compressed_len = bitpacker.compress(&my_data, &mut compressed[..], num_bits); |
| /// |
| /// assert_eq!((num_bits as usize) * BitPacker4x::BLOCK_LEN / 8, compressed_len); |
| /// |
| /// // Decompressing |
| /// let mut decompressed = vec![0u32; BitPacker4x::BLOCK_LEN]; |
| /// bitpacker.decompress(&compressed[..compressed_len], &mut decompressed[..], num_bits); |
| /// |
| /// assert_eq!(&my_data, &decompressed); |
| /// # } |
| /// ``` |
| /// |
| /// |
| /// |
| /// # Examples with delta-encoding |
| /// |
| /// Delta-encoding makes it possible to store sorted integers in an efficient manner. |
| /// Rather than encoding the integers directly, the interval (or deltas) between each of them |
| /// are computed and then encoded. |
| /// |
| /// Decoding then requires to first decode the deltas and then operate a cumulative sum (also called |
| /// integration or prefix sum) on them. |
| /// |
| /// ``` |
| /// extern crate bitpacking; |
| /// |
| /// use bitpacking::{BitPacker4x, BitPacker}; |
| /// |
| /// # fn main() { |
| /// # let my_data: Vec<u32> = vec![0, 5, 6, 8, 12, 21, 30, 38, |
| /// # 46, 52, 59, 61, 62, 62, 71, 71, 73, 74, 76, |
| /// # 77, 80, 87, 96, 99, 105, 114, 119, 121, 128, |
| /// # 133, 138, 145, 152, 161, 161, 166, 175, 176, |
| /// # 180, 186, 189, 193, 202, 211, 220, 224, 229, |
| /// # 238, 247, 255, 261, 267, 267, 268, 269, 269, |
| /// # 270, 271, 279, 283, 285, 291, 297, 303, 305, |
| /// # 309, 310, 315, 316, 316, 321, 324, 329, 337, |
| /// # 339, 342, 350, 355, 364, 373, 382, 386, 392, |
| /// # 400, 408, 414, 423, 431, 433, 436, 441, 444, |
| /// # 445, 454, 463, 463, 465, 472, 474, 477, 480, |
| /// # 488, 493, 496, 501, 503, 509, 515, 519, 526, |
| /// # 526, 532, 539, 542, 542, 542, 549, 557, 565, |
| /// # 566, 573, 578, 580, 581, 585, 588, 588, 591]; |
| /// |
| /// |
| /// // The initial value is used to compute the first delta. |
| /// // In most use cases, you will be compressing long increasing |
| /// // integer sequences. |
| /// // |
| /// // You should probably pass an initial value of `0u32` to the |
| /// // first block if you do not have any information. |
| /// // |
| /// // When encoding the second block however, you will want to pass the last |
| /// // value of the first block. |
| /// let initial_value = 0u32; |
| /// |
| /// let bitpacker = BitPacker4x::new(); |
| /// |
| /// let num_bits: u8 = bitpacker.num_bits_sorted(initial_value, &my_data); |
| /// |
| /// // A block will be take at most 4 bytes per-integers. |
| /// let mut compressed = vec![0u8; 4 * BitPacker4x::BLOCK_LEN]; |
| /// |
| /// # assert_eq!(num_bits, 4); |
| /// |
| /// let compressed_len = bitpacker.compress_sorted(initial_value, &my_data, &mut compressed[..], num_bits); |
| /// |
| /// assert_eq!((num_bits as usize) * BitPacker4x::BLOCK_LEN / 8, compressed_len); |
| /// |
| /// // Decompressing |
| /// let mut decompressed = vec![0u32; BitPacker4x::BLOCK_LEN]; |
| /// |
| /// // The initial value must be the same as the one passed |
| /// // when compressing the block. |
| /// bitpacker.decompress_sorted(initial_value, &compressed[..compressed_len], &mut decompressed[..], num_bits); |
| /// |
| /// assert_eq!(&my_data, &decompressed); |
| /// # } |
| </span><span class="kw">pub trait </span>BitPacker: Sized + Clone + Copy { |
| <span class="doccomment">/// Number of `u32` per compressed block |
| </span><span class="kw">const </span>BLOCK_LEN: usize; |
| |
| <span class="doccomment">/// Checks the available instructions set on the current |
| /// CPU and returns the best available implementation. |
| /// |
| /// Calling `.new()` is extremely cheap, and does not |
| /// require any heap allocation. It is *not* required to cache |
| /// its result too aggressively. |
| </span><span class="kw">fn </span>new() -> <span class="self">Self</span>; |
| |
| <span class="doccomment">/// 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 too small |
| /// - Panics if `decompressed` length is not exactly the `BLOCK_LEN`. |
| </span><span class="kw">fn </span>compress(<span class="kw-2">&</span><span class="self">self</span>, decompressed: <span class="kw-2">&</span>[u32], compressed: <span class="kw-2">&mut </span>[u8], num_bits: u8) -> usize; |
| |
| <span class="doccomment">/// Delta encode and compressed the `decompressed` array. |
| /// |
| /// Assumes that the elements in the `decompressed` array are sorted. |
| /// `initial` will be used to compute the first `delta`. |
| /// |
| /// # Panics |
| /// |
| /// - Panics if `initial` is greater than `decompressed[0]` |
| /// - Panics if `decompressed` is not sorted |
| /// - Panics if `decompressed`'s length is not exactly `BLOCK_LEN` |
| /// - Panics if `compressed` is not large enough to receive the compressed data |
| /// - Panics if the compressed destination array is too small. |
| /// |
| /// 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`. |
| </span><span class="kw">fn </span>compress_sorted( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| initial: u32, |
| decompressed: <span class="kw-2">&</span>[u32], |
| compressed: <span class="kw-2">&mut </span>[u8], |
| num_bits: u8, |
| ) -> usize; |
| |
| <span class="doccomment">/// Decompress the `compress` array to the `decompressed` array. |
| /// |
| /// Returns the amount of bytes that were consumed. |
| /// |
| /// # Panics |
| /// |
| /// Panics if the compressed array is too short, or the decompressed array is too short. |
| </span><span class="kw">fn </span>decompress(<span class="kw-2">&</span><span class="self">self</span>, compressed: <span class="kw-2">&</span>[u8], decompressed: <span class="kw-2">&mut </span>[u32], num_bits: u8) -> usize; |
| |
| <span class="doccomment">/// Decompress the`compress`array to the `decompressed` array. |
| /// The `compressed` array is assumed to have been delta-encoded and compressed. |
| /// |
| /// `initial` must be the value that was passed as the `initial` argument compressing |
| /// the block. |
| /// |
| /// Returns the amount of bytes that have been read. |
| /// |
| /// # Panics |
| /// |
| /// - Panics if the compressed array is too short to contain `BLOCK_LEN` elements |
| /// - Panics if the decompressed array is too short. |
| </span><span class="kw">fn </span>decompress_sorted( |
| <span class="kw-2">&</span><span class="self">self</span>, |
| initial: u32, |
| compressed: <span class="kw-2">&</span>[u8], |
| decompressed: <span class="kw-2">&mut </span>[u32], |
| num_bits: u8, |
| ) -> usize; |
| |
| <span class="doccomment">/// Returns the minimum number of bits used to represent the largest integer in the |
| /// `decompressed` block. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `decompressed`'s len is not exactly `BLOCK_LEN`. |
| </span><span class="kw">fn </span>num_bits(<span class="kw-2">&</span><span class="self">self</span>, decompressed: <span class="kw-2">&</span>[u32]) -> u8; |
| |
| <span class="doccomment">/// Returns the minimum number of bits used to represent the largest `delta` in the deltas in the |
| /// `decompressed` block. |
| /// |
| /// # Panics |
| /// |
| /// Panics if `decompressed`'s len is not exactly `BLOCK_LEN`. |
| </span><span class="kw">fn </span>num_bits_sorted(<span class="kw-2">&</span><span class="self">self</span>, initial: u32, decompressed: <span class="kw-2">&</span>[u32]) -> u8; |
| |
| <span class="doccomment">/// Returns the size of a compressed block. |
| </span><span class="kw">fn </span>compressed_block_size(num_bits: u8) -> usize { |
| <span class="self">Self</span>::BLOCK_LEN * (num_bits <span class="kw">as </span>usize) / <span class="number">8 |
| </span>} |
| } |
| |
| <span class="doccomment">/// Returns the most significant bit.&self, |
| </span><span class="kw">fn </span>most_significant_bit(v: u32) -> u8 { |
| <span class="kw">if </span>v == <span class="number">0 </span>{ |
| <span class="number">0 |
| </span>} <span class="kw">else </span>{ |
| <span class="number">32u8 </span>- (v.leading_zeros() <span class="kw">as </span>u8) |
| } |
| } |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"bitpacker1x"</span>)] |
| </span><span class="kw">mod </span>bitpacker1x; |
| <span class="attribute">#[cfg(all(feature = <span class="string">"bitpacker4x"</span>, not(debug_assertions)))] |
| </span><span class="kw">mod </span>bitpacker4x; |
| |
| <span class="attribute">#[cfg(all(feature = <span class="string">"bitpacker4x"</span>, debug_assertions))] |
| </span><span class="kw">mod </span>bitpacker4x_simple; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"bitpacker8x"</span>)] |
| </span><span class="kw">mod </span>bitpacker8x; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"bitpacker1x"</span>)] |
| </span><span class="kw">pub use </span>bitpacker1x::BitPacker1x; |
| |
| <span class="attribute">#[cfg(all(feature = <span class="string">"bitpacker4x"</span>, not(debug_assertions)))] |
| </span><span class="kw">pub use </span>bitpacker4x::BitPacker4x; |
| <span class="attribute">#[cfg(all(feature = <span class="string">"bitpacker4x"</span>, debug_assertions))] |
| </span><span class="kw">pub use </span>bitpacker4x_simple::BitPacker4x; |
| |
| <span class="attribute">#[cfg(feature = <span class="string">"bitpacker8x"</span>)] |
| </span><span class="kw">pub use </span>bitpacker8x::BitPacker8x; |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests_unit { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| |
| <span class="attribute">#[test] |
| #[should_panic(expected = <span class="string">"`decompressed`'s len is not `BLOCK_LEN=128`"</span>)] |
| </span><span class="kw">fn </span>test_num_bits_block_too_long() { |
| <span class="kw">let </span>bit_packer = BitPacker4x::new(); |
| <span class="kw">let </span>v = <span class="macro">vec!</span>[<span class="number">0u32</span>; BitPacker4x::BLOCK_LEN + <span class="number">1</span>]; |
| bit_packer.num_bits(<span class="kw-2">&</span>v[..]); |
| } |
| |
| <span class="attribute">#[test] |
| #[should_panic(expected = <span class="string">"`decompressed`'s len is not `BLOCK_LEN=128`"</span>)] |
| </span><span class="kw">fn </span>test_num_bits_block_too_short() { |
| <span class="kw">let </span>bit_packer = BitPacker4x::new(); |
| <span class="kw">let </span>v = <span class="macro">vec!</span>[<span class="number">0u32</span>; BitPacker4x::BLOCK_LEN - <span class="number">1</span>]; |
| bit_packer.num_bits(<span class="kw-2">&</span>v[..]); |
| } |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>functional_tests { |
| <span class="kw">use crate</span>::{BitPacker, BitPacker4x}; |
| <span class="kw">use </span>proptest::prelude::<span class="kw-2">*</span>; |
| |
| <span class="macro">proptest! </span>{ |
| <span class="attribute">#[test] |
| #[ignore] |
| </span><span class="kw">fn </span>check_block( |
| values <span class="kw">in </span>prop::collection::vec(u32::arbitrary(), BitPacker4x::BLOCK_LEN), |
| ) { |
| <span class="kw">let </span>bit_packer = BitPacker4x::new(); |
| <span class="kw">let </span>bit_width = bit_packer.num_bits(<span class="kw-2">&*</span>values); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>block = <span class="macro">vec!</span>[<span class="number">0u8</span>; BitPacker4x::compressed_block_size(bit_width)]; |
| bit_packer.compress(<span class="kw-2">&</span>values, <span class="kw-2">&mut </span>block, bit_width); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>decoded_values = <span class="macro">vec!</span>[<span class="number">0x10101010</span>; BitPacker4x::BLOCK_LEN]; |
| bit_packer.decompress(<span class="kw-2">&</span>block, <span class="kw-2">&mut </span>decoded_values, bit_width); |
| |
| <span class="macro">prop_assert_eq!</span>(values, decoded_values); |
| } |
| |
| <span class="attribute">#[ignore] |
| #[test] |
| </span><span class="kw">fn </span>check_sorted_block( |
| (values, init_value) <span class="kw">in </span>prop::collection::vec(u32::arbitrary(), BitPacker4x::BLOCK_LEN).prop_flat_map(|<span class="kw-2">mut </span>values| { |
| values.sort(); |
| <span class="kw">let </span>min_value = values[<span class="number">0</span>]; |
| (Just(values), (<span class="number">0</span>..=min_value)) |
| }), |
| ) { |
| <span class="kw">let </span>bit_packer = BitPacker4x::new(); |
| <span class="kw">let </span>bit_width = bit_packer.num_bits_sorted(init_value, <span class="kw-2">&*</span>values); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>block = <span class="macro">vec!</span>[<span class="number">0u8</span>; BitPacker4x::compressed_block_size(bit_width)]; |
| bit_packer.compress_sorted(init_value, <span class="kw-2">&</span>values, <span class="kw-2">&mut </span>block, bit_width); |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>decoded_values = <span class="macro">vec!</span>[<span class="number">0x10101010</span>; BitPacker4x::BLOCK_LEN]; |
| bit_packer.decompress_sorted(init_value, <span class="kw-2">&</span>block, <span class="kw-2">&mut </span>decoded_values, bit_width); |
| |
| <span class="macro">prop_assert_eq!</span>(values, decoded_values); |
| } |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../" data-current-crate="bitpacking" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
