Struct ExpertRecordHeader 

pub struct ExpertRecordHeader {
    pub layer: u32,
    pub expert: u32,
    pub inter: u32,
    pub hidden: u32,
    pub group_size: u32,
    pub scale2: [f32; 3],
    pub input_scale: [Option<f32>; 3],
}

Fixed-size, versioned header written at the front of every expert record.

Invariant D of the streaming-experts plan: disk format = resident format. Nothing is transformed at fetch time, so the format must be self-describing and versioned — there is no runtime enforcement otherwise. The header carries exactly the per-expert data that is not recomputable from the model dims: the two NVFP4 scalars per projection (weight_scale_2 and input_scale), plus enough identity/shape to detect a mismatched file.

Fields

layer: u32

expert: u32

inter: u32

hidden: u32

group_size: u32

scale2: [f32; 3]

Per-projection weight_scale_2 (per-tensor FP32 scale), gate/up/down.

input_scale: [Option<f32>; 3]

Per-projection input_scale (activation scale). None = weight-only W4A16 path with no activation scale (the streamer patches a NULL device pointer). Presence is stored out of band in a flags byte, so equality is exact (no NaN sentinel to break PartialEq).

Implementations

impl ExpertRecordHeader

pub const MAGIC: u32 = 0x5850_5254

pub const VERSION: u32 = 1

pub const BYTES: u64 = 256

Reserved on-disk header size. Generous vs. the packed fields so the format can grow without moving sub-buffer offsets.

pub fn to_bytes(&self) -> [u8; 256]

Serialize into the fixed 256-byte on-disk header block. Layout: u32 magic, u32 version, u32 layer, u32 expert, u32 inter, u32 hidden, u32 group_size, u32 input_scale_flags, f32 scale2[3], f32 input_scale[3] (0.0 where absent), zero pad to 256. input_scale_flags bit i set => projection i has an activation scale.

pub fn from_bytes(buf: &[u8]) -> Option<Self>

Parse a header block, validating magic + version. Returns None on any mismatch (wrong file, wrong version) — never panics on bad input.

Trait Implementations

impl Clone for ExpertRecordHeader

fn clone(&self) -> ExpertRecordHeader

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for ExpertRecordHeader

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

Formats the value using the given formatter.

impl PartialEq for ExpertRecordHeader

fn eq(&self, other: &ExpertRecordHeader) -> 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 Copy for ExpertRecordHeader

impl StructuralPartialEq for ExpertRecordHeader