Struct SubsetDifference 

pub struct SubsetDifference {
    pub u_mask_zero_bits: u8,
    pub uv: u32,
}

A parsed Explicit-Subset-Difference entry per Common spec §3.2.5.1.5, i.e. one row of the Explicit-Subset-Difference Record. The u_mask is the first byte (number of low-order zero bits in the full 32-bit m_u); uv is the 32-bit uv number itself.

The v_mask is derived from uv per Common spec §3.2.3 (the while ((uv & ~v_mask) == 0) v_mask <<= 1 C snippet).

Fields

u_mask_zero_bits: u8

Number of trailing zero bits in the 32-bit m_u mask — i.e. m_u = 0xFFFFFFFF << u_mask_zero_bits.

uv: u32

The 32-bit uv number itself.

Implementations

impl SubsetDifference

pub fn u_mask(&self) -> u32

Expand u_mask_zero_bits into the full 32-bit m_u.

pub fn v_mask(&self) -> u32

Derive m_v from uv per Common spec §3.2.3 (“the mask for v is given by the first lower-order 1-bit in the uv number. That bit, and all lower-order 0-bits, are zero bits in the ‘v’ mask.”). The spec’s reference C code is:

long v_mask = 0xFFFFFFFF;
while ((uv & ~v_mask) == 0) v_mask <<= 1;

i.e. the zero region of m_v is trailing_zeros(uv) + 1 bits wide — the lowest-order 1-bit AND every 0-bit below it.

Trait Implementations

impl Clone for SubsetDifference

fn clone(&self) -> SubsetDifference

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Copy for SubsetDifference

impl Debug for SubsetDifference

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Eq for SubsetDifference

impl PartialEq for SubsetDifference

fn eq(&self, other: &SubsetDifference) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for SubsetDifference