assert_never

Ensures that the value of a specified expression is not TRUE.


	Parameters: severity_level property_type msg coverage_level	Class: single-cycle assertion

Syntax

assert_never

		[#(severity_level, property_type, msg, coverage_level )]

		instance_name (clk, reset_n, test_expr );

Parameters


	severity_level	Severity of the failure. Default: ‘OVL_ERROR.
	property_type	Property type. Default: ‘OVL_ASSERT.
	msg	Error message printed when assertion fails. Default: “VIOLATION”.
	coverage_level	Coverage level. Default: ‘OVL_COVER_ALL.

Ports


	clk		Clock event for the assertion. The checker samples on the rising edge of the clock.
	reset_n		Active low synchronous reset signal indicating completed initialization.
	test_expr		Expression that should not evaluate to TRUE on the rising clock edge.

Description

The assert_never assertion checker checks the single-bit expression test_expr at each rising edge of clk to verify the expression does not evaluate to TRUE.

Assertion Checks


	ASSERT_NEVER	Expression evaluated to TRUE.
	test_expr contains X/Z value	Expression evaluated to X or Z, and ‘OVL_XCHECK_OFF is not set.

Cover Points

none

Notes

1. By default, the assert_never assertion is pessimistic and the assertion fails if test_expr is not 0 (i.e.equals 1, X, Z, etc.). However, if ‘OVL_XCHECK_OFF is set, the assertion fails if and only if test_expr is 1.

Example


assert_never #(
	‘OVL_ERROR, ‘OVL_ASSERT, “”, ‘OVL_COVER_ALL)		// severity_level // property_type // msg // coverage_level
	valid_count (
		clk, reset_n, reg_a < reg_b );	// clock // reset // test_expr

Ensures that (reg_a < reg_b) is FALSE at each rising edge of clk.

Standard OVL V1.1a