Module lanes 

Numbers bit-packed in lanes: what a frame’s list of ints is made of.

A list of n numbers width bits each (1..=32) is n / GROUP groups, then the rest packed one after another (little-endian bits). A group is GROUP numbers in LANES lanes of 32-bit words: number j goes to lane j % LANES, the j / LANES-th in it; a lane’s numbers are packed one after another into its words, and word k of lane l is the group’s k * LANES + l-th. A row of LANES numbers is shifted and merged as one 256-bit vector, so packing and unpacking run a group at a time — with the best instruction set the processor has (Backend: SSE4.2, AVX2, AVX-512, NEON), chosen once at start; the same bytes whichever. Numbers wider than 32 bits go one after another, no groups.

Number i is found in O(1) (get), so views read in place.

Enums

Backend

An instruction set that packs and unpacks groups. Every backend writes and reads the same bytes; they differ only in speed.

Constants

GROUP

Numbers in a group.

GROUP_MAX_BITS

The widest numbers packed in groups.

LANES

Lanes of a group: a 256-bit vector of 32-bit words.

Functions

get

Number i of bytes (n numbers, width bits each) — i < n.

group_bytes

A group’s bytes, its numbers width bits each.

pack

Packs items (n of them, each fitting width bits) onto out.

packed_bytes

The bytes n numbers width bits each take.

unpack

Each of the n numbers in bytes (width bits each), in order, to f.