tapestry

[WIP] A python package to add JTAG, IJTAG and TAP in DFT-inserted circuitry and do ICL and PDL — package/CLI name is warptap.

Usage

warptap is a library, not (yet) a CLI tool — import it and call its functions directly. The core pipeline is: insert a JTAG/IJTAG test-access network into your design, then either drive it (PDLInterpreter) and emit a real ATE pattern file, or hand the inserted netlist onward.

from warptap import (
    InstrumentSpec, InstrumentDirection, SignalBinding,
    insert_test_access, PDLInterpreter, to_svf,
)

# One instrument per real signal you want write/read access to.
specs = [
    InstrumentSpec(
        "ctrl_write", width=1, capture_value=0,
        direction=InstrumentDirection.WRITE,
        signal_bits=(SignalBinding("ctrl_in"),),
    ),
    InstrumentSpec(
        "status_read", width=1, capture_value=0,
        direction=InstrumentDirection.READ,
        signal_bits=(SignalBinding("status_out"),),
    ),
]

# Ingest your design, insert the TAP + SIB/instrument network, get back synthesizable Verilog
# plus everything needed to drive it.
inserted_verilog, graph, root = insert_test_access(["my_design.v"], "my_design", specs)

# Drive it: write ctrl_write, wait for it to settle, read status_read.
pdl = PDLInterpreter(graph, root)
pdl.iTarget("ctrl_write")
pdl.iWrite(1)
pdl.iApply()
pdl.iRunLoop(3)
pdl.iTarget("status_read")
pdl.iRead(1)
pdl.iApply()

# Emit a real ATE pattern file from the same ops.
print(to_svf(pdl.program))

to_stapl/to_stil render the identical pdl.program as STAPL/STIL instead; to_icl describes the inserted network's own topology as real ICL text; retarget_faultflow_patterns remaps a faultflow --export-patterns JSON export through the same network. Every exception this library raises subclasses WarptapError.

Development

Requires a real yosys on PATH (this project shells out to it, same as faultflow does for its own Yosys usage — it's never bundled). On Windows, run everything through WSL, which already has yosys/python3/pytest installed system-wide; only the package itself needs an editable install, and system pip there is externally-managed (PEP 668), so that install goes through a small local venv:

wsl bash -lc "cd /mnt/c/path/to/tapestry && python3 -m venv --system-site-packages .venv && ./.venv/bin/pip install -e ."
wsl bash -lc "cd /mnt/c/path/to/tapestry && ./.venv/bin/python -m pytest"

--system-site-packages lets the venv see WSL's system-installed pytest instead of reinstalling it. If a real yosys isn't available at all, WARPTAP_YOSYS_CMD can point at any Yosys-compatible executable — tests/conftest.py falls back to a pip-installed yowasp-yosys (WASM build, see the dev extra) if nothing is found on PATH.

Some tests also cross-simulate hand-authored RTL against its Python behavioral-model counterpart using Icarus Verilog (iverilog/vvp, already present in the documented WSL environment). There's no WASM fallback for these — if neither is on PATH nor pointed at via WARPTAP_IVERILOG_CMD/WARPTAP_VVP_CMD, those tests skip cleanly rather than failing.