Use suffix_array with cdivsufsort instead of psacak:

- Up to 200% performance boost of SAIS vs pSACAK in Rust vs Rust
- Up to 15% performance boost of SAIS vs SAIS in Rust vs Go

Author: 0xA001113

Cargo.toml

@@ -13,11 +13,11 @@ homepage = "https://spectre-network.org"
 
 [dependencies]
 fnv = "1.0.7"
-psacak = "0.1.0"
 rc4 = "0.1.0"
 salsa20 = "0.10.2"
 sha2 = "0.10.8"
 siphasher = "1.0.1"
+suffix_array = "0.5.0"
 xxhash-rust = { version = "0.8.10", features = ["xxh64"] }
 
 [dev-dependencies]

README.md

@@ -34,13 +34,16 @@ The original algorithm utilized the [SA-IS](https://en.wikipedia.org/wiki/Suffix
 sorting algorithm. There exists an enhanced one with [SACA-K](https://www.sciencedirect.com/science/article/abs/pii/S0020019016301375)
 for induced sorting, improving the linear-time complexity to be
 in-place for constant alphabets. However, this remains a single-core
-variant. Our AstroBWTv3 implementation has switched to
-[pSACAK](https://ieeexplore.ieee.org/document/8371211), a fast
-linear-time, in-place parallel algorithm that leverages multi-core
-machines. It is fully compatible with the original AstroBWTv3 Suffix
-Array.
+variant. The [pSACAK](https://ieeexplore.ieee.org/document/8371211)
+algorithm offers a fast, linear-time, in-place parallel solution that
+utilizes multi-core machines. However, testing revealed that it still
+requires optimization. It is fully compatible with the original
+AstroBWTv3 Suffix Array.
 
-There are still numerous opportunities to enhance the computation of
+Our AstroBWTv3 implementation is using `cdivsufsort` as it is still
+the fastest single threaded Suffix Array construction implementation.
+
+There are numerous opportunities to enhance the computation of
 AstroBWTv3 hashes, including:
 
 * Replacing most steps with highly optimized inline assembler code on

src/astrobwtv3.rs

@@ -8,7 +8,7 @@ use sha2::Digest;
 use sha2::Sha256;
 use siphasher::sip::SipHasher24;
 use std::hash::Hasher;
-use psacak::psacak;
+use suffix_array::SuffixArray;
 
 // This is the maximum.
 const MAX_LENGTH: u32 = (256 * 384) - 1;
@@ -2457,9 +2457,9 @@ pub fn astrobwtv3_hash(input: &[u8]) -> [u8; 32] {
     let data_len = (tries - 4) as u32 * 256 + (((data[253] as u64) << 8 | (data[254] as u64)) as u32 & 0x3ff);
 
     // Step 6: build our suffix array.
-    let scratch_sa = psacak(&scratch_data[..data_len as usize]);
+    let scratch_sa = SuffixArray::new(&scratch_data[..data_len as usize]);
     let mut scratch_sa_bytes: Vec<u8> = vec![];
-    for vector in &scratch_sa {
+    for vector in &scratch_sa.into_parts().1[1..(data_len as usize + 1)] {
 
         // Little and big endian.
         if cfg!(target_endian = "little") {