Add -PMAR option to emit MIDI marker meta-events for P: part labels (#16)

* Add -PMAR option to output `P:` information as MIDI part meta-event

* Update man page and comments

* Add the instance number of a part like `Part T-4`

This allows better tracking of parts played more than once with complex `P:`
header.

* Updated CHANGES file and added author change comments in the code

doc/CHANGES

@@ -15675,3 +15675,16 @@ February 24 2026
 
 midistats: the summary includes ntimesig, triplets, unquantized when appropriate.
 
+March 30 2026 [RK]
+
+abc2midi: added -PMAR option to emit MIDI marker meta-events (0x06) for
+P: part labels. When a header P: field specifies a play order (e.g.
+P:(AB)3), a marker is emitted each time a section begins during the
+expanded playback, with an instance number (e.g. "Part A-1", "Part B-2").
+When no header P: field is present, inline P: labels in the body are
+emitted as simple section markers (e.g. "Part A"). The existing code at
+genmidi.c:3187 that was meant to write markers was unreachable dead code;
+it has been restructured. Changes in genmidi.c (PART case in writetrack,
+partmarkers global) and store.c (event_part, event_init for -PMAR flag).
+Man page updated in doc/abc2midi.1.
+

doc/abc2midi.1

@@ -2,7 +2,7 @@
 .SH NAME
 \fBabc2midi\fP \- converts abc file to MIDI file(s)
 .SH SYNOPSIS
-abc2midi \fIinfile\fP [\fIrefnum\fP] [\-c] [\-v] [\-ver] [\-t] [\-n limit] [\-CS] [\-quiet] [\-silent] [\-Q tempo] [\-NFNP] [\-NFER] [\-NGRA] [\-NGUI] [\-STFW] [\-OCC] [\-NCOM] [\-HARP] [\-BF] [\-TT] [\-o outfile] \-CSM [filename]
+abc2midi \fIinfile\fP [\fIrefnum\fP] [\-c] [\-v] [\-ver] [\-t] [\-n limit] [\-CS] [\-quiet] [\-silent] [\-Q tempo] [\-NFNP] [\-NFER] [\-NGRA] [\-NGUI] [\-STFW] [\-OCC] [\-NCOM] [\-PMAR] [\-HARP] [\-BF] [\-TT] [\-o outfile] \-CSM [filename]
 .SH DESCRIPTION
  The default action is to write a MIDI file for each abc tune
  with the filename <stem>N.mid, where <stem> is the filestem
@@ -61,6 +61,14 @@ Place lyric text in separate MIDI tracks.
 .B -NCOM
 Suppress some comments in the output MIDI file.
 .TP
+.B -PMAR
+Emit MIDI marker meta-events for P: part labels. When a header P: field
+specifies a play order (e.g. P:(AB)3), a marker is emitted each time a
+section begins during the expanded playback, with an instance number
+appended (e.g. "Part A-1", "Part B-1", "Part A-2", "Part B-2").
+When no header P: field is present, inline P: labels in the body are
+emitted as simple section markers (e.g. "Part A", "Part B").
+.TP
 .B -OCC
 Accept old chord convention (eg +D2G2+ instead of [DG]2).
 .TP

genmidi.c

@@ -105,6 +105,7 @@ int gchordbars;
 /* Part handling */
 extern struct vstring part;
 int parts, partno, partlabel;
+int partmarkers; /* -PMAR flag: emit MIDI marker meta-events for P: parts [RK] 2026-03-30 */
 int part_start[26], part_count[26];
 long introlen, lastlen, partlen[26];
 int partrepno;
@@ -3123,17 +3124,33 @@ long writetrack(int xtrack)
         checksyllables();
       };
       break;
-    case PART:
+    case PART: /* [RK] 2026-03-30 */
       in_varend = 0;
-      /*j = partbreak(xtrack, trackvoice, j); [SS] 2023.01.20 */
-      j = findvoice(j, trackvoice, xtrack);
-
       if (parts == -1) {
-        char msg[1];
-
-        msg[0] = (char) pitch[j];
-        mf_write_meta_event(0L, marker, msg, 1);
-      };
+        /* No header P: spec, body labels only: emit "Part X" */
+        if (partmarkers && xtrack == 0 &&
+            pitch[j] >= 'A' && pitch[j] <= 'Z') {
+          char msg[8];
+          snprintf(msg, sizeof(msg), "Part %c", (char) pitch[j]);
+          mf_write_meta_event(delta_time_track0, marker, msg, strlen(msg));
+          tracklen = tracklen + delta_time_track0;
+          delta_time_track0 = 0L;
+        }
+      } else {
+        /* Parts active, navigate then emit "Part X-N" marker
+           where N is the instance number (1-based) */
+        /*j = partbreak(xtrack, trackvoice, j); [SS] 2023.01.20 */
+        j = findvoice(j, trackvoice, xtrack);
+        if (partmarkers && xtrack == 0 &&
+            partlabel >= 0 && partlabel < 26) {
+          char msg[20];
+          snprintf(msg, sizeof(msg), "Part %c-%d",
+                   (char)(partlabel + 'A'), part_count[partlabel]);
+          mf_write_meta_event(delta_time_track0, marker, msg, strlen(msg));
+          tracklen = tracklen + delta_time_track0;
+          delta_time_track0 = 0L;
+        }
+      }
       break;
     case VOICE:
       /* search on for next occurrence of voice */

store.c

@@ -422,6 +422,7 @@ int apply_fermata_to_chord = 0; /* [SS] 2012-03-26 */
 /* Part handling */
 struct vstring part;
 extern int parts, partno, partlabel;
+extern int partmarkers; /* [RK] 2026-03-30 */
 extern int part_start[26], part_count[26];
 
 int voicesused;
@@ -945,6 +946,13 @@ void event_init(int argc, char *argv[], char **filename)
     nocom = 0;
   }
 
+  /* [RK] 2026-03-30 */
+  if (getarg("-PMAR", argc, argv) != -1) {
+    partmarkers = 1;
+  } else {
+    partmarkers = 0;
+  }
+
   if (getarg("-STFW",argc,argv) != -1) {
     separate_tracks_for_words = 1;
   } else {
@@ -1025,7 +1033,7 @@ void event_init(int argc, char *argv[], char **filename)
     printf("abc2midi version %s\n",VERSION);
     printf("Usage : abc2midi <abc file> [reference number] [-c] [-v] ");
     printf("[-o filename]\n");
-    printf("        [-t] [-n <value>] [-CS] [-NFNP] [-NCOM] [-NFER] [-NGRA] [-NGUI] [-HARP]\n");
+    printf("        [-t] [-n <value>] [-CS] [-NFNP] [-NCOM] [-NFER] [-NGRA] [-NGUI] [-HARP] [-PMAR]\n");
     printf("        [reference number] selects a tune\n");
     printf("        -c  selects checking only\n");
     printf("        -v  selects verbose option\n");
@@ -1039,6 +1047,7 @@ void event_init(int argc, char *argv[], char **filename)
     printf("        -Q default tempo (quarter notes/minute)\n");
     printf("        -NFNP don't process !p! or !f!-like fields\n");
     printf("        -NCOM suppress comments in output MIDI file\n");
+    printf("        -PMAR emit MIDI marker meta-events for P: part labels\n"); /* [RK] 2026-03-30 */
     printf("        -NFER ignore all fermata markings\n");
     printf("        -NGRA ignore grace notes\n");
     printf("        -NGUI ignore guitar chord indications\n");
@@ -2893,7 +2902,13 @@ void event_part(char *s)
   if (dotune) {
     p = s;
     skipspace(&p);
-    if (pastheader && parts == -1) return; /* [SS] 2014-04-10 */
+    if (pastheader && parts == -1) { /* [RK] 2026-03-30 */
+      /* No header P: spec. If -PMAR, store body P: as section label */
+      if (partmarkers && ((int)*p >= 'A') && ((int)*p <= 'Z')) {
+        addfeature(PART, (int)*p, 0, 0);
+      }
+      return;
+    }
     if (pastheader) {
       if (((int)*p < 'A') || ((int)*p > 'Z')) {
         if (!silent) event_error("Part must be one of A-Z");