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Signal Attributes

• Attributes Are Named Characteristics of an Object (or Type) Which has a Value That Can Be Referenced.

SIGNAL ATTRIBUTES

• S`Event -- Is TRUE if Signal S Has Changed.

• S`Stable(t) -- Is TRUE if Signal S Has Been Stable For the Last ``t`` Period. If t=0; it is written as S`Stable

• S`Last_value -- Returns the Previous Value of ``S`` Before the Last Change.

Examples : An Edge-Triggered D-FF

D_FF: PROCESS(CLK)

Begin

IF (CLK`Event and CLK = `1`) Then

Q <= D After TDelay;

END IF;

END Process;