Struct PackedLayout 

pub struct PackedLayout {
    pub bitmap_bytes: u32,
    pub data_start: u32,
    pub align: u32,
    pub fields: Vec<PackedField>,
    pub class_masks: [u64; 4],
}

Packed layout: the block is a presence bitmap followed by slots for the present fields only, grouped into size classes (8/4/2/1 bytes) in that order. Block size and every slot offset depend on which fields are present, so both are computed per message from the bitmap — in O(1) via popcount. Limited to 64 fields so the bitmap fits one u64 rank word.

Fields

bitmap_bytes: u32

Presence bitmap size, ceil(field_count / 8) bytes (1..=8).

data_start: u32

Offset where field data begins: align_up(bitmap_bytes, align).

align: u32

Max field alignment across the schema (>= 1).

fields: Vec<PackedField>

Per field position (ID-sorted).

class_masks: [u64; 4]

class_masks[k] has bit p set iff field p belongs to size class CLASS_SIZES[k].

Implementations

impl PackedLayout

pub fn field_offset(&self, bitmap: u64, pos: usize) -> u32

Byte offset of field pos (which must be present) given the message’s presence bitmap. O(1): a fixed number of popcounts.

pub fn block_size(&self, bitmap: u64) -> u32

Total block size for a message with this presence bitmap.

Trait Implementations

impl Clone for PackedLayout

fn clone(&self) -> PackedLayout

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for PackedLayout

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

Formats the value using the given formatter.

impl Eq for PackedLayout

impl PartialEq for PackedLayout

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

Equality operator ==.

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

Inequality operator !=.

impl StructuralPartialEq for PackedLayout