From 38c6156e6cc30b3b64f07f4f279b3dab1f18ff46 Mon Sep 17 00:00:00 2001
From: Meisam <meisambahadori@gmail.com>
Date: Thu, 30 Jul 2026 11:08:14 +0200
Subject: [PATCH] Add missing files

---
 src/frontend/com_qpxf.c | 97 +++++++++++++++++++++++++++++++++++++++++
 src/frontend/com_qpxf.h |  7 +++
 2 files changed, 104 insertions(+)
 create mode 100644 src/frontend/com_qpxf.c
 create mode 100644 src/frontend/com_qpxf.h

diff --git a/src/frontend/com_qpxf.c b/src/frontend/com_qpxf.c
new file mode 100644
index 000000000..ffcac2d5d
--- /dev/null
+++ b/src/frontend/com_qpxf.c
@@ -0,0 +1,97 @@
+/**********
+Enhancement-141: two-tone small-signal QPXF (quasi-periodic transfer function) --
+`qpxf <output_node> <f_in>`.
+
+The adjoint of QPAC: around the QPSS operating point retained by a prior
+`qpss <expr> <f1> <f2> hb`, one adjoint solve of the 2-D conversion matrix gives the
+transfer from an input at every sideband f_in + k1*f1 + k2*f2 to the chosen output at
+f_in. By reciprocity the sideband-(0,0) transfer equals the QPAC response at that node.
+The engine is QPXFanalyze() (spicelib/analysis/dcpss.c); this command resolves the
+output node and runs it.
+**********/
+
+#include "ngspice/ngspice.h"
+#include "ngspice/cpdefs.h"
+#include "ngspice/cktdefs.h"
+#include "ngspice/ftedefs.h"
+#include "ngspice/fteext.h"
+#include "ngspice/wordlist.h"
+#include "ngspice/cpextern.h"
+
+#include "com_qpxf.h"
+
+static double qpxfnum(const char *w)
+{
+    char *s = (char *) w;
+    double v = 0.0;
+    if (ft_numparse(&s, FALSE, &v) < 0)
+        v = atof(w);
+    return v;
+}
+
+static int qpxf_node(CKTcircuit *ckt, const char *name)
+{
+    int numNames = 0, i, num = 0;
+    IFuid *nameList = NULL;
+    if (CKTnames(ckt, &numNames, &nameList) != OK || !nameList)
+        return 0;
+    for (i = 0; i < numNames; i++)
+        if (nameList[i] && strcmp((const char *) nameList[i], name) == 0) { num = i + 1; break; }
+    tfree(nameList);
+    return num;
+}
+
+void
+com_qpxf(wordlist *wl)
+{
+    CKTcircuit *ckt;
+    double f_in;
+    int    outNode, verbose, err;
+
+    if (!ft_curckt || !ft_curckt->ci_ckt) {
+        fprintf(cp_err, "Error: qpxf: there is no circuit loaded.\n");
+        return;
+    }
+    ckt = ft_curckt->ci_ckt;
+    if (!wl || !wl->wl_next) {
+        fprintf(cp_err, "Usage: qpxf <output_node> <f_in>   (run `qpss <expr> <f1> <f2> hb` first)\n");
+        return;
+    }
+    outNode = qpxf_node(ckt, wl->wl_word);
+    if (outNode <= 0) { fprintf(cp_err, "Error: qpxf: unknown output node '%s'.\n", wl->wl_word); return; }
+    {   /* sweep form: qpxf <out> <dec|oct|lin> <N> <fstart> <fstop> -> xf/xf_conv plot */
+        extern int qp_steptype(const char *w);
+        extern int qp_sweep_maxpts(int stepType, int np, double fstart, double fstop);
+        extern void qp_emit_plot(const char *plotname, const char *title, double *freqs, int npts,
+                                 char **vnames, int nvec, double *data);
+        int st = qp_steptype(wl->wl_next->wl_word);
+        if (st >= 0) {
+            double fstart, fstop, *freqs, *data; int np, npts, maxpts;
+            char *vn[2] = { (char*)"xf", (char*)"xf_conv" };
+            wordlist *w = wl->wl_next->wl_next;
+            if (!w || !w->wl_next || !w->wl_next->wl_next) {
+                fprintf(cp_err, "Usage: qpxf <output_node> <dec|oct|lin> <N> <fstart> <fstop>\n"); return;
+            }
+            np = (int) qpxfnum(w->wl_word);
+            fstart = qpxfnum(w->wl_next->wl_word);
+            fstop  = qpxfnum(w->wl_next->wl_next->wl_word);
+            if (np < 1 || fstart <= 0.0 || fstop < fstart) { fprintf(cp_err, "Error: qpxf: bad sweep spec.\n"); return; }
+            maxpts = qp_sweep_maxpts(st, np, fstart, fstop);
+            freqs = TMALLOC(double, maxpts); data = TMALLOC(double, (size_t)maxpts*2);
+            npts = QPXFsweep(ckt, outNode, st, np, fstart, fstop, freqs, data);
+            if (npts > 0) {
+                qp_emit_plot("qpxf", "QPXF Analysis", freqs, npts, vn, 2, data);
+                fprintf(cp_out, "qpxf: swept %d points into a new plot (now current); `plot xf xf_conv` to view.\n", npts);
+            } else fprintf(cp_err, "qpxf: sweep did not complete.\n");
+            FREE(freqs); FREE(data);
+            return;
+        }
+    }
+    f_in = qpxfnum(wl->wl_next->wl_word);
+    if (f_in <= 0.0) { fprintf(cp_err, "Error: qpxf: need f_in > 0.\n"); return; }
+
+    verbose = cp_getvar("qpxf_verbose", CP_BOOL, NULL, 0);
+    err = QPXFanalyze(ckt, outNode, f_in, verbose ? 1 : 0);
+    if (err != OK)
+        fprintf(cp_err, "qpxf: quasi-periodic transfer function did not complete (error %d).\n", err);
+}
diff --git a/src/frontend/com_qpxf.h b/src/frontend/com_qpxf.h
new file mode 100644
index 000000000..c507f40c5
--- /dev/null
+++ b/src/frontend/com_qpxf.h
@@ -0,0 +1,7 @@
+#ifndef ngspice_COM_QPXF_H
+#define ngspice_COM_QPXF_H
+
+/* Enhancement-141: two-tone small-signal QPXF (quasi-periodic transfer function). */
+void com_qpxf(wordlist *wl);
+
+#endif