array_demo.va

`include "disciplines.vams"

// Enhancement-14 demonstration: array literals / aggregates.
//
// A 4-tap programmable-gain buffer whose gain is the sum of four tap weights.
// It exercises all three Enhancement-14 capabilities at once:
//
//   (B) array-valued PARAMETER  `parameter real [0:3] w = '{...}` -- the tap
//       weights, each element carrying its own default and each individually
//       overridable from SPICE as `w[0]`, `w[1]`, ...
//   (A) whole-array AGGREGATE assignment `acc = '{w[0], w[1], w[2], w[3]}` and
//       array-to-array copy `rev = acc`.
//   (C) DYNAMIC (non-constant) indexing `rev[i]` / `acc[3-i]` inside `for`
//       loops -- a runtime element select over the array variables.
//
// The gain g = w[0]+w[1]+w[2]+w[3]. With the defaults (0.1+0.2+0.3+0.4 = 1.0)
// V(out) tracks V(in) exactly; overriding the weights rescales it.
module array_demo(in, out);
    input in;
    output out;
    electrical in, out;

    // (B) array-valued parameter -- per-element defaults, per-element override
    parameter real [0:3] w = '{0.1, 0.2, 0.3, 0.4};

    real [0:3] acc;      // working accumulator (array variable)
    real [0:3] rev;      // reversed copy
    integer i;
    real g;

    analog begin
        // (A) aggregate assignment: build the accumulator from the param taps
        acc = '{w[0], w[1], w[2], w[3]};

        // (C) dynamic write + dynamic read with a computed index: reverse acc
        for (i = 0; i < 4; i = i + 1)
            rev[i] = acc[3 - i];

        // (C) dynamic read: sum the reversed accumulator
        g = 0.0;
        for (i = 0; i < 4; i = i + 1)
            g = g + rev[i];

        V(out) <+ g * V(in);
    end
endmodule