What the SVF inspector validates
The parser recognizes the standard command families ENDDR, ENDIR, FREQUENCY, HDR/HIR, PIO/PIOMAP, RUNTEST, SDR/SIR, STATE, TDR/TIR, and TRST. It checks terminating semicolons, scan lengths, hexadecimal TDI/TDO/MASK/SMASK values, duplicate and unknown parameters, stable end states, explicit TAP transition paths, RUNTEST forms, and bounded counts. Both ! and // line comments are ignored.
Shifted bits versus payload bits
An SIR or SDR payload is not always the entire scan. HIR/TIR and HDR/TDR define instruction- or data-register header and trailer bits added around later scans, commonly to bypass other devices in a chain. The report captures the active padding at every scan and shows both payload and total shifted length. TDO comparison counts use the applicable MASK; when no mask is supplied for a TDO field, all declared bits are counted.
Timing and sticky scan data
A numeric FREQUENCY lets the inspector estimate the clock contribution of later TCK-based RUNTEST commands. Explicit SEC minimums are also accumulated, but host latency, adapter limits, state transitions, SCK behavior, and device polling are not modeled. An omitted TDI field can reuse prior same-type scan data under SVF’s sticky behavior; the report labels explicit, sticky, and initial-zero contexts instead of silently presenting them as equivalent.
JTAG and device-safety boundary
Passing this structural audit does not mean an SVF is authentic, compatible, complete, or safe to execute. SVF can erase, program, configure, or test attached devices. This tool does not know the scan chain, instruction-register lengths, BSDL definitions, device state, voltages, adapter capabilities, security policy, or whether TDO would match. PIO/PIOMAP content is only inventoried. Verify the file’s provenance and target-specific instructions, use the approved player and probe, preserve recoverable images, and control power and access before hardware execution.
Frequently asked questions
Does this run the SVF?
No. It parses text and calculates a report only. There is no WebUSB, serial, network, probe, or JTAG connection.
Can it prove the expected TDO values are correct?
No. It can validate that TDO and MASK values fit their declared bit lengths and count comparison bits, but only a correctly configured player communicating with the intended chain can observe TDO.
Why is PIO reported with a warning?
Parallel I/O mappings and vectors depend on board wiring and player capabilities. The commands are retained in the inventory, but their electrical meaning cannot be validated from the SVF alone.
Does the timing estimate predict programming duration?
No. It is a lower-bound accounting of explicit SEC waits and TCK cycles where a numeric frequency is available. Transfers, adapter throughput, state changes, retries, and target behavior add time.
Format references: the vendor-independent Serial Vector Format Specification, Revision E and OpenOCD’s boundary-scan command documentation.
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