Struct SequencedSlotsLayout 

#[repr(C, align(64))]
pub struct SequencedSlotsLayout<const N: usize> {
    pub header: LayoutHeader,
    pub initialized: IndexbusAtomicU32,
    pub _pad0: u32,
    pub _pad_to_64: [u8; 40],
    pub cursor: IndexbusAtomicU64,
    pub _pad_cursor: [u8; 56],
    pub gating: [SequencerGatingCell; N],
    pub slot_pool: SlotPoolLayout,
    pub ring: [IndexbusAtomicU32; 1024],
}

ByteOr sequenced-slots region: sequencer + slot pool + a fixed ring of slot indices.

This region is the ABI substrate for pipeline lanes that need:

• strict per-lane ordering (via a sequencer cursor), and
• payload storage in shared memory (via fixed-size slots), and
• replay by sequence within the bounded ring window.

v1 notes:

• Capacity is fixed by the IndexBus ABI constant INDEXBUS_QUEUE_CAPACITY.
• Each published sequence seq maps to ring[seq % INDEXBUS_QUEUE_CAPACITY].
• Producers must not wrap past the minimum gating sequence (Disruptor-style).

Fields

header: LayoutHeader

Common region header (magic/version/capabilities/layout size).

initialized: IndexbusAtomicU32

0 = uninitialized, 1 = initializing, 2 = initialized

_pad0: u32

Padding (reserved).

_pad_to_64: [u8; 40]

Pad to 64 so the first counter starts at offset 64.

cursor: IndexbusAtomicU64

Producer cursor (monotonic sequence).

_pad_cursor: [u8; 56]

Padding to keep the cursor in its own cache line.

gating: [SequencerGatingCell; N]

Per-consumer gating sequences.

slot_pool: SlotPoolLayout

Slot pool storing payload bytes.

ring: [IndexbusAtomicU32; 1024]

Ring mapping seq -> slot index.

Entries use INDEXBUS_EMPTY_FREE_U32 as the “uninitialized” sentinel.

Implementations

impl<const N: usize> SequencedSlotsLayout<N>

pub const REQUIRED_CAPS: u32

Capabilities required for this region to be considered compatible.

pub const REGION_KIND: u16 = flags::BYTEOR_REGION_KIND_SEQUENCED_SLOTS

Region kind discriminator stored in LayoutHeader.flags.

pub const REGION_KIND_MASK: u16 = ib_flags::INDEXBUS_FLAGS_REGION_KIND_MASK

Mask for the low 8 bits containing the region kind discriminator.

pub const EMPTY_RING: u32 = indexbus_abi::INDEXBUS_EMPTY_FREE_U32

Sentinel stored in ring entries before a slot is published.