Module spvd_encode 

PVD (pvData) Encoding Helpers

Minimal encoder for NTScalar introspection and value updates.

Functions

compute_changed_bits

Walks desc in pre-order (matching the PVA wire convention that bit 0 represents the whole root structure and subsequent bits correspond to fields in pre-order) and returns a per-bit flag vector marking leaves whose value differs between prev and next.

decode_pv_request_fields

Parse a pvRequest structure from the INIT body bytes and return the list of requested field paths.

decode_pv_request_options

Decode the record._options key/value pairs from a pvRequest body.

decoded_values_equal

Structural equality for DecodedValue with NaN treated as equal to NaN (avoids spurious monitor flaps when a float field is NaN on both sides).

encode_decoded_projected

Re-encode a DecodedValue::Structure against a (possibly narrowed) descriptor, omitting fields that are not present in the descriptor.

encode_decoded_value

Encode a DecodedValue back to PVA wire bytes.

encode_nt_enum_full

encode_nt_ndarray_full

encode_nt_payload_bitset

encode_nt_payload_bitset_parts

encode_nt_payload_delta

Encode a sparse monitor-data delta between prev and next projected onto filtered_desc. Returns None if nothing changed in the filtered view (caller should suppress the update). Otherwise returns (bitset, values) with only the changed leaves marked and encoded.

encode_nt_payload_filtered

Encode only the fields of an NtPayload whose paths appear in filtered_desc. The bitset and value bytes are computed against the filtered descriptor so that a client that received the filtered INIT descriptor will decode them correctly.

encode_nt_payload_full

encode_nt_payload_values_for_desc

Encode the value bytes of an NtPayload projected onto a (possibly narrowed) descriptor. Fields not represented in desc are omitted; sub-structures are encoded recursively.

encode_nt_scalar_array_full

encode_nt_scalar_bitset

encode_nt_scalar_bitset_parts

encode_nt_scalar_full

encode_nt_table_full

encode_pv_request

Build a pvRequest structure for the given field paths.

encode_pv_request_with_options

Build a pvRequest structure with extra record._options key/value pairs.

encode_pv_value

Encode a PvValue tree to PVA wire bytes (values only, no descriptor).

encode_size_pvd

encode_string_pvd

encode_structure_desc

filter_structure_desc

Filter a StructureDesc to include only the listed field paths.

nt_enum_desc

nt_ndarray_desc

nt_ndarray_desc_default

nt_payload_desc

nt_scalar_array_desc

nt_scalar_desc

nt_table_desc

pv_value_desc

Build a StructureDesc from a PvValue::Structure.