Function pack_witness 

pub fn pack_witness<P: PackedField<Scalar = B128>, A: Allocator>(
    alloc: &A,
    log_witness_elems: usize,
    witness: &[Word],
) -> Result<FieldVec<P, A>, Error>

Packs committed witness words into the field buffer committed as the trace oracle.

Two 64-bit words are packed little-endian into one 128-bit field element. The element sequence is zero-padded up to 2^log_witness_elems.

Arguments

• alloc: the allocator the packed buffer is drawn from.
• log_witness_elems: base-2 logarithm of the committed field-element count.
• witness: the committed witness words, in value-vector order.

Returns

The packed multilinear over log_witness_elems variables, ready to commit.

Errors

Returns an error when the words do not fit in 2^log_witness_elems field elements.