fix(params): decode ProcessData descriptor Length per Table B.6#12
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The ProcessData In/Out descriptor (Direct Parameter Page 1, Figure B.5) carries Length in bits 0-4 only; bit 6 is SIO and bit 7 is BYTE. The decoder masked the whole byte, so a device that legally sets the SIO bit had its PD length corrupted, and BYTE=0 sub-byte lengths were truncated by integer division instead of rounded up. Mask to bits 0-4 and round bit lengths up to whole octets, matching Table B.6. Also documents the V1.1.5 conformance audit in IMPLEMENTATION_STATUS.md: field encodings are conformant; the startup/OPERATE-transition octets (should be MC=0xA2 read then MasterCommand 0x99) and the ISDU I-Service nibble (Table A.12) are known co-designed deviations from the device stack, pending a coordinated change. New parameter test covers SIO-bit and sub-byte descriptors. 14/14 ctest, strict compile, and cppcheck green.
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Part of a V1.1.5 spec-conformance audit. This is the one deviation that is safe to fix in isolation (it only affects decoding a device-reported descriptor — no wire-protocol/interop change).
Bug
The ProcessData In/Out descriptor (Direct Parameter Page 1, Figure B.5) carries Length in bits 0-4 only; bit 6 is SIO, bit 7 is BYTE. The decoder masked the whole byte (
& 0x7F//8), so:0xC3→ 68 octets instead of 4);Fix
Mask Length to bits 0-4 and round bit lengths up to whole octets, per Table B.6. All existing byte-aligned descriptors decode identically; new test covers the SIO-bit and sub-byte cases.
Audit context (documented, not fixed here)
docs/IMPLEMENTATION_STATUS.mdnow records the full audit. Field encodings (MinCycleTime B.3, Direct Parameter B.1, M-seqCapability B.3, MC octet A.1/A.2) are conformant. Two co-designed deviations remain and need a coordinated master+device change (they'd break the on-wire model until both land):MC=0xA2(read MinCycleTime) then MasterCommand0x99"DeviceOperate" on the page channel — not a bare0x0F;0x9/0xA/0xB(read) /0x1/0x2/0x3(write) per Table A.12 — not0x08/0x09.14/14 ctest (incl. new Table B.6 test), strict compile, cppcheck green.