Improve reading the source code sequence by extra comments:

While searching for 'Parsing the circuit', the sequence of major
functions is revealed.

src/frontend/inp.c

@@ -530,7 +530,9 @@ inp_spsource(FILE *fp, bool comfile, char *filename, bool intfile)
     char *dir_name = ngdirname(filename ? filename : ".");
 
     startTime = seconds();
-    /* inp_source() called with fp: load from file, */
+    /* Parsing the circuit 2.
+       This is the next major step:
+       inp_source() called with fp: load circuit netlist from file, */
     /* called with *fp == NULL and intfile: we want to load circuit from circarray */
     if (fp || intfile) {
         deck = inp_readall(fp, dir_name, filename, comfile, intfile, &expr_w_temper);
@@ -931,7 +933,9 @@ inp_spsource(FILE *fp, bool comfile, char *filename, bool intfile)
                 }
             }
 
-            /* Now expand subcircuit macros and substitute numparams.*/
+            /* Parsing the circuit 4.
+               This is the next major step:
+               Expand subcircuit macros and substitute numparams.*/
             if (!cp_getvar("nosubckt", CP_BOOL, NULL, 0))
                 if ((deck->nextcard = inp_subcktexpand(deck->nextcard)) == NULL) {
                     line_free(realdeck, TRUE);
@@ -1084,7 +1088,9 @@ inp_spsource(FILE *fp, bool comfile, char *filename, bool intfile)
            if (newcompat.hs || newcompat.spe)
               rem_unused_mos_models(deck->nextcard);
 #endif
-            /* now load deck into ft_curckt -- the current circuit. */
+            /* Parsing the circuit 5.
+               This is the next major step:
+               load deck into ft_curckt -- the current circuit. */
             if(inp_dodeck(deck, tt, wl_first, FALSE, options, filename) != 0)
                 return 1;
 
@@ -1411,6 +1417,10 @@ inp_dodeck(
      *---------------------------------------------------*/
     if (!noparse) {
         startTime = seconds();
+        /* Parsing the circuit 6.
+           This is the next major step:
+           Input a single deck, and return a pointer to the circuit.
+           Parse all models and instances */
         ckt = if_inpdeck(deck, &tab);
         ft_curckt->FTEstats->FTESTATnetParseTime = seconds() - startTime;
         /* if .probe, rename the current measurement node vcurr_ */

src/frontend/inpcom.c

@@ -1054,6 +1054,10 @@ struct card *inp_readall(FILE *fp, const char *dir_name, const char* file_name,
     /* set the members of the compatibility structure */
     set_compat_mode();
 
+    /* Parsing the circuit 3.
+       This is the next major step:
+       Reading the netlist line by line, handle .include and .lib,
+       line continuation and upper/lower casing */
     rv = inp_read(fp, 0, dir_name, file_name, comfile, intfile);
     cc = rv.cc;
 

src/frontend/spiceif.c

@@ -93,8 +93,9 @@ static int finddev(CKTcircuit *ckt, char *name, GENinstance **devptr, GENmodel *
 /* espice fix integration */
 static int finddev_special(CKTcircuit *ckt, char *name, GENinstance **devptr, GENmodel **modptr, int *device_or_model);
 
-/* Input a single deck, and return a pointer to the circuit. */
-
+/* Input a single deck, and return a pointer to the circuit. 
+   Parse all models in function INPpas1, instances (devices) in INPpas2,
+   consider initial conditions (INPpas3), and shunt capacitors (INPpas4). */
 CKTcircuit *
 if_inpdeck(struct card *deck, INPtables **tab)
 {
@@ -162,16 +163,23 @@ if_inpdeck(struct card *deck, INPtables **tab)
 
     ft_curckt->ci_curTask = ft_curckt->ci_defTask;
 
-    /* Parse the .model lines. Enter the model into the global model table modtab. */
     modtab = NULL;
     modtabhash = NULL;
-    /* Parse .model lines, put them into 'tab' */
+    /* Parsing the circuit 7.
+       This is the next major step:
+       Parse the .model lines.
+       Enter the model into the global model table modtab
+       and into the corresponding hash table modtabhash.
+       The role of 'tab' is unclear (not used any more?). */
     INPpas1(ckt, deck->nextcard, *tab);
-    /* store the new model table in the current circuit */
+    /* store the new model tables in the current circuit */
     ft_curckt->ci_modtab = modtab;
     ft_curckt->ci_modtabhash = modtabhash;
 
-    /* Scan through the instance lines and parse the circuit. */
+    /* Parsing the circuit 8.
+       This is the next major step:
+       Scan through the instance lines and parse the circuit.
+       Set up the circuit matrix. */
     INPpas2(ckt, deck->nextcard, *tab, ft_curckt->ci_defTask);
 #ifdef XSPICE
     if (!Evtcheck_nodes(ckt, *tab)) {

src/main.c

@@ -1490,7 +1490,10 @@ int main(int argc, char **argv)
             gotone = FALSE; // Re-use
 
             if (tempfile && (!err || !ft_batchmode)) {
-                /* Copy the input file name for becoming another file search path */
+                /* Parsing the circuit 1.
+                   This is the next major step:
+                   Source the input file, then parse the data and create the circuit.
+                   Copy the input file name for becoming another file search path */
                 if (inp_spsource(tempfile, FALSE, dname, FALSE) != 0) {
                     fprintf(stderr, "    Simulation interrupted due to error!\n\n");
                     if (ft_stricterror || (oflag && !cp_getvar("interactive", CP_BOOL, NULL, 0)))

src/spicelib/parser/inppas1.c

@@ -8,9 +8,8 @@ Author: 1985 Thomas L. Quarles
 #include "inppas1.h"
 
 /*
- * The first pass of the circuit parser just looks for '.model' lines
- */
-
+   The first pass of the circuit parser just looks for '.model' lines,
+   and sticks model into model table tab. */
 void INPpas1(CKTcircuit *ckt, struct card *deck, INPtables * tab)
 {
     struct card *current;

src/winmain.c

@@ -1340,7 +1340,9 @@ wWinMain(_In_ HINSTANCE hInstance, _In_opt_ HINSTANCE hPrevInstance, _In_ LPWSTR
     /* Wait until everything is settled */
     WaitForIdle();
 
-    /* Go to main() */
+    /* Parsing the command line.
+       This is the next major step:
+       Go to main() for reading the start command line and preparing the simulator. */
     nReturnCode = xmain(argc, argv);
 
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