@User: I was wondering if you might consider implementing my LUT extension for digital components for ngspice in Xyce. Apart from ngspice using

A

for digital devices where Xyce uses

U

, the general implementation is very similar in both simulators. The idea here is that you have a single digital behavioral device type called "LUT" (look-up table) that can arbitrarily map any combinatorial function of N inputs and M outputs. It declares its N and M inputs and outputs, and one extra parameter called

table_values

where

table_values

is a character string representing the output values for every input combination of 0 and 1. So

table_values="01"

is a buffer,

table_values="0001"

is a 2-input AND gate,

table_values="1111100010001000"

is a 2x2-input OAI gate. It has the great advantage of (1) being easy to implement, and (2) being able to be mapped by a simple script to the entire combinatorial logic gate set of any standard cell library. For the ngspice version, I wrote a script that parses a standard cell library liberty file for all the "function()" records, decodes the function, and then automatically converts any SPICE netlist using standard cells to its digital equivalent. I have used that process to do mixed-mode simulations of complete RISC-V cores in ngspice.