abc2midi: fix -PMAR perturbing note timing and end-of-track time (#26)

Emitting a Marker meta-event from the PART case wrote the event with
delta_time_track0 (correct, since that's the conductor-track accumulator)
but did not also reset delta_time. On track 0 in multi-track mode,
delta_time also accumulates via timestep() and is what writetrack()
returns to the MIDI library as the end-of-track delta — so each marker
left a stale delta_time that pushed the end-of-track event past the end
of the music. In single-track mode (ntracks == 1), markers were written
with delta_time_track0 too, but delta_time is the only relevant counter
in that mode, so notes following each marker were shifted later.

Fix: mirror the TEMPO handler — on ntracks == 1 use delta_time and reset
it; on ntracks != 1 keep using delta_time_track0 for the event delta but
also zero delta_time so the end-of-track is not inflated.

Reported by James Allwright with the partdemo.abc test case (now in
samples/), which exercises the parts != -1 path (header P:BACDBAC plus
body P: labels A/B/C/D). James independently fixed the same bug in his
abc2midiu fork in r32 (commit 34b7c32, "Add -PMAR option for part
markers"), where the equivalent reset is on the single delta_time
counter — his fork having retired delta_time_track0 in an earlier
refactor. Verified that mftext output of the generated MIDI is now
byte-identical to the non-PMAR output except for the added Marker
events, on both partdemo.abc (single-track) and samples/demo.abc tune 5
with P:(AB)3 (multi-track).

Add a CMake/CTest regression test (abc2midi_pmar_partdemo) that locks in
the post-fix mftext output. To support it, add_golden_test() gains an
optional NAME (to register multiple tests against the same TYPE+SAMPLE
pair) and an optional ABC2MIDI_ARGS (forwarded to the abc2midi
invocation in run_via_mid). Reverting the genmidi.c fix makes the new
test fail; reapplying it makes it pass.

genmidi.c

@@ -3132,9 +3132,17 @@ long writetrack(int xtrack)
             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));
+          if (ntracks != 1) {
-          tracklen = tracklen + delta_time_track0;
+            mf_write_meta_event(delta_time_track0, marker, msg, strlen(msg));
-          delta_time_track0 = 0L;
+            tracklen = tracklen + delta_time_track0;
+            delta_time_track0 = 0L;
+            /* delta_time also accumulates on track 0; keep it in sync so
+               the end-of-track event is not pushed out beyond the music */
+            delta_time = 0L;
+          } else {
+            mf_write_meta_event(delta_time, marker, msg, strlen(msg));
+            delta_time = 0L;
+          }
         }
       } else {
         /* Parts active, navigate then emit "Part X-N" marker
@@ -3146,9 +3154,17 @@ long writetrack(int xtrack)
           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));
+          if (ntracks != 1) {
-          tracklen = tracklen + delta_time_track0;
+            mf_write_meta_event(delta_time_track0, marker, msg, strlen(msg));
-          delta_time_track0 = 0L;
+            tracklen = tracklen + delta_time_track0;
+            delta_time_track0 = 0L;
+            /* delta_time also accumulates on track 0; keep it in sync so
+               the end-of-track event is not pushed out beyond the music */
+            delta_time = 0L;
+          } else {
+            mf_write_meta_event(delta_time, marker, msg, strlen(msg));
+            delta_time = 0L;
+          }
         }
       }
       break;

samples/partdemo.abc

@@ -0,0 +1,15 @@
+X: 3
+T:Test
+M:4/4
+L:1/8
+P:BACDBAC
+K:G
+P:A
+%%MIDI channel 5
+%%MIDI program 5 55
+P:B
+AGGF G2 G2 |
+P:C
+d c/2B/2 AB c B/2A/2 GB|:AGGF G2 G2 :|
+P:D
+%%MIDI transpose 7

tests/CMakeLists.txt

@@ -38,12 +38,23 @@ foreach(bin IN LISTS ABCMIDI_BINARIES)
   list(APPEND BINARY_DEFS "-D${BIN_UPPER}=$<TARGET_FILE:${bin}>")
 endforeach()
 
-# Helper: register a golden test for one program against one sample
+# Helper: register a golden test for one program against one sample.
+#
+# Optional NAME overrides the default test name (${TYPE}_${stem}); use this
+# when registering multiple tests against the same TYPE+SAMPLE pair (e.g. a
+# plain abc2midi run and a -PMAR run on the same input).
+#
+# Optional ABC2MIDI_ARGS forwards extra arguments to the abc2midi invocation
+# (only meaningful for TYPEs that go ABC -> MIDI -> diff).
 function(add_golden_test)
-  cmake_parse_arguments(T "" "TYPE;SAMPLE" "" ${ARGN})
+  cmake_parse_arguments(T "" "TYPE;SAMPLE;NAME" "ABC2MIDI_ARGS" ${ARGN})
 
-  get_filename_component(stem "${T_SAMPLE}" NAME_WE)
+  if(T_NAME)
-  set(test_name "${T_TYPE}_${stem}")
+    set(test_name "${T_NAME}")
+  else()
+    get_filename_component(stem "${T_SAMPLE}" NAME_WE)
+    set(test_name "${T_TYPE}_${stem}")
+  endif()
 
   add_test(
     NAME "${test_name}"
@@ -52,6 +63,7 @@ function(add_golden_test)
       -DSAMPLE=${SAMPLES_DIR}/${T_SAMPLE}
       -DGOLDEN=${GOLDEN_DIR}/${test_name}.txt
       -DTMPDIR=${TEST_TMPDIR}
+      "-DABC2MIDI_ARGS=${T_ABC2MIDI_ARGS}"
       ${BINARY_DEFS}
       -P "${CMAKE_CURRENT_SOURCE_DIR}/run_test.cmake"
   )
@@ -67,6 +79,17 @@ endforeach()
 add_golden_test(TYPE abc2midi SAMPLE demo.abc)
 add_golden_test(TYPE abc2abc  SAMPLE demo.abc)
 
+# Regression test for the -PMAR option (Part Marker meta-events).
+# Locks in marker emission and verifies the markers do not perturb note
+# timing or end-of-track time (bug fixed by carrying delta_time alongside
+# delta_time_track0 when emitting markers on the conductor track).
+add_golden_test(
+  TYPE          abc2midi
+  SAMPLE        partdemo.abc
+  NAME          abc2midi_pmar_partdemo
+  ABC2MIDI_ARGS -PMAR
+)
+
 # --- Regenerate-golden convenience target ---
 #
 # Usage:  cmake --build build/debug --target update-golden

tests/golden/abc2midi_pmar_partdemo.txt

@@ -0,0 +1,141 @@
+Header format=0 ntrks=1 division=480
+Track start
+Time=0  Meta Text, type=0x01 (Text Event)  leng=10
+     Text = <note track>
+Time=0  Tempo, microseconds-per-MIDI-quarter-note=500000
+Time=0  Key signature, sharp/flats=1  minor=0
+Time=0  Time signature=4/4  MIDI-clocks/click=48  32nd-notes/24-MIDI-clocks=8
+Time=0  Meta Text, type=0x01 (Text Event)  leng=3
+     Text = <X:3>
+Time=0  Meta Text, type=0x03 (Sequence/Track Name)  leng=4
+     Text = <Test>
+Time=1  Meta Text, type=0x06 (Marker)  leng=8
+     Text = <Part B-1>
+Time=1  Note on, chan=1 pitch=69 vol=105
+Time=240  Note off, chan=1 pitch=69 vol=0
+Time=241  Note on, chan=1 pitch=67 vol=80
+Time=480  Note off, chan=1 pitch=67 vol=0
+Time=481  Note on, chan=1 pitch=67 vol=80
+Time=720  Note off, chan=1 pitch=67 vol=0
+Time=721  Note on, chan=1 pitch=66 vol=80
+Time=960  Note off, chan=1 pitch=66 vol=0
+Time=961  Note on, chan=1 pitch=67 vol=95
+Time=1440  Note off, chan=1 pitch=67 vol=0
+Time=1441  Note on, chan=1 pitch=67 vol=80
+Time=1920  Note off, chan=1 pitch=67 vol=0
+Time=1921  Meta Text, type=0x06 (Marker)  leng=8
+     Text = <Part A-1>
+Time=1921  Program, chan=5 program=55
+Time=1921  Meta Text, type=0x06 (Marker)  leng=8
+     Text = <Part C-1>
+Time=1921  Note on, chan=5 pitch=74 vol=105
+Time=2160  Note off, chan=5 pitch=74 vol=0
+Time=2161  Note on, chan=5 pitch=72 vol=80
+Time=2280  Note off, chan=5 pitch=72 vol=0
+Time=2281  Note on, chan=5 pitch=71 vol=80
+Time=2400  Note off, chan=5 pitch=71 vol=0
+Time=2401  Note on, chan=5 pitch=69 vol=80
+Time=2640  Note off, chan=5 pitch=69 vol=0
+Time=2641  Note on, chan=5 pitch=71 vol=80
+Time=2880  Note off, chan=5 pitch=71 vol=0
+Time=2881  Note on, chan=5 pitch=72 vol=95
+Time=3120  Note off, chan=5 pitch=72 vol=0
+Time=3121  Note on, chan=5 pitch=71 vol=80
+Time=3240  Note off, chan=5 pitch=71 vol=0
+Time=3241  Note on, chan=5 pitch=69 vol=80
+Time=3360  Note off, chan=5 pitch=69 vol=0
+Time=3361  Note on, chan=5 pitch=67 vol=80
+Time=3600  Note off, chan=5 pitch=67 vol=0
+Time=3601  Note on, chan=5 pitch=71 vol=80
+Time=3840  Note off, chan=5 pitch=71 vol=0
+Time=3841  Note on, chan=5 pitch=69 vol=105
+Time=4080  Note off, chan=5 pitch=69 vol=0
+Time=4081  Note on, chan=5 pitch=67 vol=80
+Time=4320  Note off, chan=5 pitch=67 vol=0
+Time=4321  Note on, chan=5 pitch=67 vol=80
+Time=4560  Note off, chan=5 pitch=67 vol=0
+Time=4561  Note on, chan=5 pitch=66 vol=80
+Time=4800  Note off, chan=5 pitch=66 vol=0
+Time=4801  Note on, chan=5 pitch=67 vol=95
+Time=5280  Note off, chan=5 pitch=67 vol=0
+Time=5281  Note on, chan=5 pitch=67 vol=80
+Time=5760  Note off, chan=5 pitch=67 vol=0
+Time=5761  Note on, chan=5 pitch=69 vol=105
+Time=6000  Note off, chan=5 pitch=69 vol=0
+Time=6001  Note on, chan=5 pitch=67 vol=80
+Time=6240  Note off, chan=5 pitch=67 vol=0
+Time=6241  Note on, chan=5 pitch=67 vol=80
+Time=6480  Note off, chan=5 pitch=67 vol=0
+Time=6481  Note on, chan=5 pitch=66 vol=80
+Time=6720  Note off, chan=5 pitch=66 vol=0
+Time=6721  Note on, chan=5 pitch=67 vol=95
+Time=7200  Note off, chan=5 pitch=67 vol=0
+Time=7201  Note on, chan=5 pitch=67 vol=80
+Time=7680  Note off, chan=5 pitch=67 vol=0
+Time=7681  Meta Text, type=0x06 (Marker)  leng=8
+     Text = <Part D-1>
+Time=7681  Meta Text, type=0x06 (Marker)  leng=8
+     Text = <Part B-2>
+Time=7681  Note on, chan=5 pitch=76 vol=105
+Time=7920  Note off, chan=5 pitch=76 vol=0
+Time=7921  Note on, chan=5 pitch=74 vol=80
+Time=8160  Note off, chan=5 pitch=74 vol=0
+Time=8161  Note on, chan=5 pitch=74 vol=80
+Time=8400  Note off, chan=5 pitch=74 vol=0
+Time=8401  Note on, chan=5 pitch=73 vol=80
+Time=8640  Note off, chan=5 pitch=73 vol=0
+Time=8641  Note on, chan=5 pitch=74 vol=95
+Time=9120  Note off, chan=5 pitch=74 vol=0
+Time=9121  Note on, chan=5 pitch=74 vol=80
+Time=9600  Note off, chan=5 pitch=74 vol=0
+Time=9601  Meta Text, type=0x06 (Marker)  leng=8
+     Text = <Part A-2>
+Time=9601  Program, chan=5 program=55
+Time=9601  Meta Text, type=0x06 (Marker)  leng=8
+     Text = <Part C-2>
+Time=9601  Note on, chan=5 pitch=81 vol=105
+Time=9840  Note off, chan=5 pitch=81 vol=0
+Time=9841  Note on, chan=5 pitch=79 vol=80
+Time=9960  Note off, chan=5 pitch=79 vol=0
+Time=9961  Note on, chan=5 pitch=78 vol=80
+Time=10080  Note off, chan=5 pitch=78 vol=0
+Time=10081  Note on, chan=5 pitch=76 vol=80
+Time=10320  Note off, chan=5 pitch=76 vol=0
+Time=10321  Note on, chan=5 pitch=78 vol=80
+Time=10560  Note off, chan=5 pitch=78 vol=0
+Time=10561  Note on, chan=5 pitch=79 vol=95
+Time=10800  Note off, chan=5 pitch=79 vol=0
+Time=10801  Note on, chan=5 pitch=78 vol=80
+Time=10920  Note off, chan=5 pitch=78 vol=0
+Time=10921  Note on, chan=5 pitch=76 vol=80
+Time=11040  Note off, chan=5 pitch=76 vol=0
+Time=11041  Note on, chan=5 pitch=74 vol=80
+Time=11280  Note off, chan=5 pitch=74 vol=0
+Time=11281  Note on, chan=5 pitch=78 vol=80
+Time=11520  Note off, chan=5 pitch=78 vol=0
+Time=11521  Note on, chan=5 pitch=76 vol=105
+Time=11760  Note off, chan=5 pitch=76 vol=0
+Time=11761  Note on, chan=5 pitch=74 vol=80
+Time=12000  Note off, chan=5 pitch=74 vol=0
+Time=12001  Note on, chan=5 pitch=74 vol=80
+Time=12240  Note off, chan=5 pitch=74 vol=0
+Time=12241  Note on, chan=5 pitch=73 vol=80
+Time=12480  Note off, chan=5 pitch=73 vol=0
+Time=12481  Note on, chan=5 pitch=74 vol=95
+Time=12960  Note off, chan=5 pitch=74 vol=0
+Time=12961  Note on, chan=5 pitch=74 vol=80
+Time=13440  Note off, chan=5 pitch=74 vol=0
+Time=13441  Note on, chan=5 pitch=76 vol=105
+Time=13680  Note off, chan=5 pitch=76 vol=0
+Time=13681  Note on, chan=5 pitch=74 vol=80
+Time=13920  Note off, chan=5 pitch=74 vol=0
+Time=13921  Note on, chan=5 pitch=74 vol=80
+Time=14160  Note off, chan=5 pitch=74 vol=0
+Time=14161  Note on, chan=5 pitch=73 vol=80
+Time=14400  Note off, chan=5 pitch=73 vol=0
+Time=14401  Note on, chan=5 pitch=74 vol=95
+Time=14880  Note off, chan=5 pitch=74 vol=0
+Time=14881  Note on, chan=5 pitch=74 vol=80
+Time=15360  Note off, chan=5 pitch=74 vol=0
+Time=15386  Meta event, end of track
+Track end

tests/run_test.cmake

@@ -68,8 +68,11 @@ endfunction()
 # Convert ${SAMPLE} to MIDI, then run ${bin} on the resulting MIDI file and
 # capture its stdout.  Any extra arguments are inserted BEFORE the MIDI path
 # (needed e.g. for "midi2abc -f <file>").
+#
+# ABC2MIDI_ARGS (set by the caller, possibly empty) is forwarded as a CMake
+# list to the abc2midi invocation, so callers can opt into flags like -PMAR.
 function(run_via_mid outfile bin)
-  run_or_die("${ABC2MIDI}" "${SAMPLE}" -o "${midfile}" -quiet -silent)
+  run_or_die("${ABC2MIDI}" "${SAMPLE}" ${ABC2MIDI_ARGS} -o "${midfile}" -quiet -silent)
   run_to_file("${outfile}" "${bin}" ${ARGN} "${midfile}")
 endfunction()