//! Memory packing layout utilities.

/// Memory layout for packed matrices

#[derive(Debug, Clone, Copy, PartialEq, Eq)]

pub enum PackingLayout {

    /// Row-major (C-style)

    RowMajor,

    /// Column-major (Fortran-style)

    ColumnMajor,

    /// Panel-major for A (Goto algorithm)

    PanelMajorA,

    /// Panel-major for B (Goto algorithm)

    PanelMajorB,

}

/// Calculate packed index for panel-major A layout

///

/// Panel-major stores micro-panels contiguously for sequential access.

#[must_use]

#[inline]

pub fn pack_a_index(row: usize, col: usize, mr: usize, kc: usize, _mc: usize) -> usize {

    let panel = row / mr;

    let row_in_panel = row % mr;

    panel * mr * kc + col * mr + row_in_panel

}

/// Calculate packed index for panel-major B layout

#[must_use]

#[inline]

pub fn pack_b_index(row: usize, col: usize, nr: usize, kc: usize, _nc: usize) -> usize {

    let panel = col / nr;

    let col_in_panel = col % nr;

    panel * kc * nr + row * nr + col_in_panel

}

/// Apply XOR swizzling for shared memory bank conflict avoidance

///

/// Pattern: idx_swizzled = idx ^ (idx >> 5) for 32-bank architectures.

#[must_use]

#[inline]

pub fn swizzle_index(idx: usize) -> usize {

    idx ^ (idx >> 5)

}