pixie::experimental::GroupedSlotOrder256 Class Reference

Experimental ordering of 256 pointer slots in one 16x16 node. More...

#include <grouped_slot_order256.h>

Public Member Functions
	GroupedSlotOrder256 (std::size_t count=0) noexcept
	Identity ordering of count live slots; requires count <= 256.
std::size_t	size () const noexcept
	Number of live logical slots in [0, 256].
unsigned	operator[] (std::size_t index) const noexcept
	Physical slot for zero-based index; requires index < size().
bool	occupied (std::size_t slot) const noexcept
	Whether physical slot is live; requires slot < capacity.
bool	valid () const noexcept
	Check mapping uniqueness and occupancy without allocation.
std::size_t	rotate_children (std::array< void *, capacity > &pointers, std::size_t left, std::size_t right, std::size_t distance) noexcept
	Rotate logical [left,right) left, updating order and pointer slots.

Static Public Attributes
static constexpr std::size_t	capacity = 256
	Maximum occupied child count.

Detailed Description

Experimental ordering of 256 pointer slots in one 16x16 node.

Seventeen packed 64-bit permutations select the physical group and the physical slot within it. Per-group occupancy bitmaps describe live physical slots. Only the final logical group may be partial. This is one node allocation, not sixteen separately allocated intermediate nodes.

Whole-group and within-group rotations move only ordering metadata. A rotation of full groups with a non-group-aligned distance exchanges at most eight pointers per group. Other boundary combinations use bounded scratch pointer storage. No operation allocates, owns, or destroys pointees; callers supply live slots and retain ownership. Subtree sizes are maintained by the caller in logical order. Invalid arguments violate asserted preconditions.

Member Function Documentation

rotate_children()

std::size_t pixie::experimental::GroupedSlotOrder256::rotate_children ( std::array< void *, capacity > & pointers, std::size_t left, std::size_t right, std::size_t distance )

inlinenoexcept

Rotate logical [left,right) left, updating order and pointer slots.

Requires left <= right <= size(). Distance is reduced modulo length; empty ranges are unchanged. Inactive pointers are never read or written. No pointee moves. Scratch storage is bounded by 256 pointers.

Returns

Number of writes to physical pointer slots (excludes metadata).

---

The documentation for this class was generated from the following file:

• include/pixie/experimental/grouped_slot_order256.h