A top-level diagram of the XSPICE system integrated into ngspice is shown in Fig. 25.1. The XSPICE Simulator is made up of the NGSPICE core, the event-driven algorithm, circuit description syntax parser extensions, a loading routine for code models, and the Nutmeg user interface. The XSPICE Code Model Subsystem consists of the Code Model Generator, 5 standard code model library sources with more than 40 code models, the sources for Node Type Libraries, and all the interfaces to User-Defined Code Models and to User-Defined Node Types.

Figure 25.1: ngspice/XSPICE Top-Level Diagram