Types of Stimulus Generation in e-language

Stimulus needs to be generated and driven to the DUT in order verification process.

The Specman Elite e-language supports two types of stimulus generation :

i) Pre-Run Generation

ii) On-the-Fly Generation

Pre-Run Generates fields or struct once the Specman Test command is issued and sends them to the DUT with the help of BFM. The main advantage of this process is, it quickly shows what the generator will produce but consumes lot of memory in order to save all the generated values.
Pre-Run generation requires an understanding of the interface between struct definition and the Specman Elite Constraint Solver.

Ex: top file name : packet_top.e
<’

import packet.e;

extend sys{

Legal: bool;

Packet: packet_s;// Instantiate of struct

};

‘>



On-The–Fly Generation Generates items “on-the-fly” at the time they are driven into the DUT. On-the-Fly generation is achieved by using the “!” (Bang operator) Before the field, so that initially the field will be empty.
The main advantage of this mechansim is that it saves memory and the generation can be activated based on the DUT interaction.

Ex: top file name : packet_top.e
<’

import packet.e;

extend sys {

! Cur_packet: packet_s;

! Packet_count: uint;

};

‘>

** sys is a Specman Elite pre-defined struct