matrixmultiply 0.3.11

General matrix multiplication for f32 and f64 matrices. Operates on matrices with general layout (they can use arbitrary row and column stride). Detects and uses SIMD features on x86/x86-64 and AArch64 transparently for higher performance. Uses a microkernel strategy, so that the implementation is easy to parallelize and optimize. Supports multithreading.
Documentation 
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//! Copyright 2026 Ulrik Sverdrup "bluss"

pub(crate) const fn slice_eq(a: &[u8], b: &[u8]) -> bool {
    if a.len() != b.len() { return false; }
    let mut i = 0;
    while i < a.len() {
        if a[i] != b[i] { return false; }
        i += 1;
    }
    true
}

const fn find_byte(text: &[u8], byte: u8) -> Option<usize> {
    let mut j = 0;
    while j < text.len() && text[j] != byte {
        j += 1;
    }
    if j == text.len() { None } else { Some(j) }
}

/// Search for exact word match in string of comma separated words
///
/// Example "avx2,fma", "avx2" => true; "avx2,fma", "avx" => false
pub(crate) const fn comma_separated_contains(text: &str, word: &str) -> bool {
    let mut text = text.as_bytes();
    loop {
        let next_comma = find_byte(text, b',');
        let word_end = match next_comma { Some(x) => x, None => text.len() };
        let (this_word, _) = text.split_at(word_end);
        if slice_eq(this_word, word.as_bytes()) {
            return true;
        }

        // take next segment
        if let None = next_comma {
            return false;
        }
        let (_, tail) = text.split_at(word_end + 1);
        text = tail;
    }
}

#[test]
fn test_find_byte() {
    assert_eq!(find_byte(b"abc", b'z'), None);
    assert_eq!(find_byte(b"abc", b'b'), Some(1));
}

#[test]
fn test_comma_separated_contains() {
    assert!(comma_separated_contains("abc,xyz", "abc"));
    assert!(comma_separated_contains("abc,xyz", "xyz"));
    assert!(!comma_separated_contains("abc,xyz", "abc,"));
    assert!(!comma_separated_contains("avx2,fma", "avx"));
}