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//! Alignment utility functions

/// Align an address downwards, returning the greatest X with alignment `align`
/// so that x <= addr. The alignment must be a power of two.
///
/// # Panics
///
/// Will panic if `align` is not a power of two.
pub fn align_down(addr: usize, align: usize) -> usize {
    if align.is_power_of_two() {
        addr & !(align - 1)
    } else if align == 0 {
        addr
    } else {
        panic!("non power-of-two alignment");
    }
}

/// Align an address upwards, returning the smallest X with alignment `align`
/// so that x >= addr. The alignment must be a power of two.
///
/// # Panics
///
/// Will panic if `align` is not a power of two.
pub fn align_up(addr: usize, align: usize) -> usize {
    align_down(addr + align - 1, align)
}