feat(adr-118/p1.5): payload section parser (BfldPayload) — 32/32 GREEN
Iter 5. Implements ADR-119 §2.2 payload layout: 4-byte LE length prefix
followed by section bytes, in this fixed order:
compressed_angle_matrix ‖ amplitude_proxy ‖ phase_proxy ‖ snr_vector
‖ csi_delta (iff flags.bit0)
‖ vendor_extension (length 0 allowed)
Added:
- src/payload.rs (gated on `feature = "std"`):
* BfldPayload struct with 6 fields (csi_delta: Option<Vec<u8>>)
* SECTION_PREFIX_LEN const (= 4)
* to_bytes(include_csi_delta: bool) -> Vec<u8>
* wire_len(include_csi_delta: bool) -> usize (predictive, no allocation)
* from_bytes(&[u8], expect_csi_delta: bool) -> Result<Self, BfldError>
* push_section / read_section helpers (private)
- BfldError::MalformedSection { offset, reason } variant
- pub use BfldPayload from lib.rs (cfg-gated mirror of BfldFrame)
tests/payload_sections.rs (8 named tests, all green):
payload_roundtrip_with_csi_delta
payload_roundtrip_without_csi_delta
wire_len_matches_to_bytes_length
empty_payload_has_five_zero_length_sections
parser_rejects_buffer_shorter_than_first_length_prefix
parser_rejects_section_body_running_past_buffer_end
parser_rejects_trailing_bytes_after_vendor_extension
csi_delta_flag_mismatch_with_payload_is_detectable_via_trailing_bytes
ACs progressed:
- AC5 ↑ — full section-level round-trip preservation (round-trip with and
without csi_delta both pass).
- AC6 ↑ — deterministic section encoding (length prefixes use to_le_bytes,
body is byte-stable).
- AC1 partial — section layout now parses with bounded errors; CBFR-specific
parsing (Phi/Psi Givens decoders) is a separate iter inside extractor.rs.
Test config:
- cargo test --no-default-features → 17 passed (payload module cfg-out)
- cargo test → 32 passed (3 + 6 + 7 + 8 + 8)
Out of scope (next iter target):
- Wire integration: feed BfldPayload bytes through BfldFrame::new so the
header.payload_crc32 covers the section-prefixed bytes per ADR-119 §2.2
("CRC32 covers all section bytes including length prefixes").
- A no_std-friendly BfldPayloadRef<'_> borrowing variant (ESP32-S3 path).
- Givens-rotation angle decoder (Phi/Psi extraction from compressed_angle_matrix).
Co-Authored-By: claude-flow <ruv@ruv.net>
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