Glossary

BFM

Bus Functional Model

blocking function

A function that blocks the caller until the function finishes. This is typically a regular function, but sometimes involves calls to threaded code which blocks execution for an indeterminate amount of time. See also the Python glossary.

coroutine function

The definition of a function that, when called, returns a coroutine object. Implemented using async functions. See also the Python glossary.

coroutine

The result of calling a coroutine function. Coroutines are not run immediately, you must either await on them which blocks the awaiting coroutine until it is finished; or turn them into a task, which can be run concurrently. See also the Python glossary.

task

A coroutine that can be run concurrently to other tasks.

trigger

An awaitable object which when awaited will block the current task until its condition is met. For example, a RisingEdge(dut.clk) trigger will block until the next rising edge of the dut.clk signal.

DUT

Design under Test

DUV

Design under Verification

FLI

Foreign Language Interface. Mentor Graphics’ equivalent to VHPI.

GPI

Generic Procedural Interface, cocotb’s abstraction over VPI, VHPI, and FLI.

HAL

Hardware Abstraction Layer

HDL

Hardware Description Language

MDV

Metric-driven Verification

RTL

Register Transfer Level

UVM

Universal Verification Methodology

VHPI

The VHDL Procedural Interface, an application-programming interface to VHDL tools.

VIP

Verification IP

VPI

The Verilog Procedural Interface, an application-programming interface to (System)Verilog tools. Its original name was “PLI 2.0”.

time step

A single point in simulated time, comprised of a series of one or more evaluation cycles.

evaluation cycle

One iteration of the evaluation loop in a time step. Occurs when HDL or cocotb code is executed in reaction to events, such as simulated time advancing or signal or variable values changing. The executed code tends to create more events, leading to the next evaluation cycle.

inertial deposit

Depositing a value on a signal or variable at the end of the current delta cycle.

no-delay deposit

Depositing a value on a signal or variable immediately.

driving

Continuously depositing a value to a signal. cocotb cannot drive signals.

deposit

Setting the value of a signal or variable once. May be inertial or no-delay.

force

Setting the value to a signal or variable once immediately, then locking it so the value can’t change.

release

Setting the value to a signal or variable once immediately, then unlocking it from a previous force.

simulator object

An addressable object from the DUT. Corresponds to a signal, variable, or hierarchical element in the HDL code.