Struct QuantDesc 

#[repr(C)]
pub struct QuantDesc {
    pub len: u64,
    pub axis_plus_one: u64,
    pub scales: SendConstPtr<f32>,
    pub zero_points: SendConstPtr<i32>,
}

Quantization metadata, in a form that can cross an .so boundary.

crate::TensorDesc deliberately does not carry this: it is the shared descriptor, pinned by ABI_VERSION and consumed by the C API, where tensors travel as real ef_tensor handles into one shared libedgefirst_tensor.so and no reconstruction ever happens. The Python packages are the only consumers that rebuild a tensor from a descriptor, so this rides in the capsule payload rather than widening a C ABI that does not need it.

Variable-length by nature – per-channel quantization carries one scale (and optionally one zero-point) per channel – so the arrays are borrowed, not inlined: scales/zero_points point into the Quantization that TensorCapsulePayload::quant_keepalive owns, on exactly the terms crate::TensorDesc::ptr borrows the producer’s host address. A consumer copies the values out during import (see QuantDesc::to_quantization) while the capsule is still alive, and never retains the pointers.

Fields

len: u64

Number of entries in scales (and in zero_points when non-null). Zero means the tensor carries no quantization – the one field a consumer must check before reading either pointer.

axis_plus_one: u64

Channel axis for per-channel quantization, plus one; 0 means per-tensor. Encoded this way so the whole struct zeroes to “absent” rather than needing a separate presence flag for an Option<usize>.

scales: SendConstPtr<f32>

len scale factors. Null iff len == 0.

zero_points: SendConstPtr<i32>

len zero-points, or null for symmetric quantization.

Implementations

impl QuantDesc

pub const fn absent() -> Self

The descriptor for a tensor with no quantization metadata.

pub fn borrowing(quant: &Quantization) -> Self

Describe quant, borrowing its arrays.

The caller must keep quant alive for as long as the descriptor is readable – in the capsule protocol, by storing the same Arc in TensorCapsulePayload::quant_keepalive.

pub unsafe fn to_quantization(&self) -> Result<Option<Quantization>>

Copy the borrowed arrays into an owned crate::Quantization, or None when the producer declared no quantization.

Ok(None) means “the producer has none”; a descriptor that declares quantization but cannot be read back as a valid crate::Quantization is an Err, not a second spelling of None. Conflating the two is what made the bug this whole capsule version exists to fix so hard to place: a tensor that quietly arrives unquantized surfaces much later as the consumer’s own “requires quantization metadata”, which names the symptom and not the cause.

Safety

self must have come from a capsule that is still alive, so the arrays scales/zero_points point at are still owned by the producer’s quant_keepalive.

Trait Implementations

impl Clone for QuantDesc

fn clone(&self) -> Self

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for QuantDesc

impl Debug for QuantDesc

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

Formats the value using the given formatter.