Deprecate usage of the system timer for the sequencer (#599)

Deprecate usage of the system timer for the sequencer and print a warning if the system timer is used.

doc/fluidsynth-v20-devdoc.txt

@@ -21,6 +21,7 @@ All the source code examples in this document are in the public domain; you can
 
 - \ref Disclaimer
 - \ref Introduction
+- \ref NewIn2_1_1
 - \ref NewIn2_1_0
 - \ref NewIn2_0_8
 - \ref NewIn2_0_7
@@ -67,6 +68,10 @@ What is FluidSynth?
 
 - FluidSynth is open source, in active development. For more details, take a look at http://www.fluidsynth.org
 
+\section NewIn2_1_1 What's new in 2.1.1?
+
+- using the sequencer with the system timer as timing source has been deprecated
+
 \section NewIn2_1_0 What's new in 2.1.0?
 
 - <span style="color:red">refrain from using fluid_synth_set_sample_rate()</span>

doc/fluidsynth_arpeggio.c

@@ -57,7 +57,7 @@ schedule_noteoff(int chan, short key, unsigned int ticks)
 
 /* schedule a timer event (shall trigger the callback) */
 void
-schedule_timer_event()
+schedule_timer_event(void)
 {
     fluid_event_t *ev = new_fluid_event();
     fluid_event_set_source(ev, -1);
@@ -69,7 +69,7 @@ schedule_timer_event()
 
 /* schedule the arpeggio's notes */
 void
-schedule_pattern()
+schedule_pattern(void)
 {
     int i, note_time, note_duration;
     note_time = time_marker;
@@ -124,7 +124,7 @@ main(int argc, char *argv[])
 
         if(n != -1)
         {
-            sequencer = new_fluid_sequencer();
+            sequencer = new_fluid_sequencer2(0);
             /* register the synth with the sequencer */
             synth_destination = fluid_sequencer_register_fluidsynth(sequencer,
                                 synth);

doc/fluidsynth_metronome.c

@@ -47,7 +47,7 @@ schedule_noteon(int chan, short key, unsigned int ticks)
 
 /* schedule a timer event (shall trigger the callback) */
 void
-schedule_timer_event()
+schedule_timer_event(void)
 {
     fluid_event_t *ev = new_fluid_event();
     fluid_event_set_source(ev, -1);
@@ -59,7 +59,7 @@ schedule_timer_event()
 
 /* schedule the metronome pattern */
 void
-schedule_pattern()
+schedule_pattern(void)
 {
     int i, note_time;
     note_time = time_marker;
@@ -111,7 +111,7 @@ main(int argc, char *argv[])
 
         if(n != -1)
         {
-            sequencer = new_fluid_sequencer();
+            sequencer = new_fluid_sequencer2(0);
             /* register the synth with the sequencer */
             synth_destination = fluid_sequencer_register_fluidsynth(sequencer,
                                 synth);

include/fluidsynth/seq.h

@@ -41,7 +41,7 @@ typedef void (*fluid_event_callback_t)(unsigned int time, fluid_event_t *event,
                                        fluid_sequencer_t *seq, void *data);
 
 
-FLUIDSYNTH_API fluid_sequencer_t *new_fluid_sequencer(void);
+FLUID_DEPRECATED FLUIDSYNTH_API fluid_sequencer_t *new_fluid_sequencer(void);
 FLUIDSYNTH_API fluid_sequencer_t *new_fluid_sequencer2(int use_system_timer);
 FLUIDSYNTH_API void delete_fluid_sequencer(fluid_sequencer_t *seq);
 FLUIDSYNTH_API int fluid_sequencer_get_use_system_timer(fluid_sequencer_t *seq);

src/midi/fluid_seq.c

@@ -88,6 +88,7 @@ static void _fluid_free_evt_queue(fluid_evt_entry **first, fluid_evt_entry **las
  * new_fluid_sequencer2() to specify whether the system timer or
  * fluid_sequencer_process() is used to advance the sequencer.
  * @return New sequencer instance
+ * @deprecated As of fluidsynth 2.1.1 the use of the system timer has been deprecated.
  */
 fluid_sequencer_t *
 new_fluid_sequencer(void)
@@ -102,12 +103,18 @@ new_fluid_sequencer(void)
  *   the sequencer.
  * @return New sequencer instance
  * @since 1.1.0
+ * @note As of fluidsynth 2.1.1 the use of the system timer has been deprecated.
  */
 fluid_sequencer_t *
 new_fluid_sequencer2(int use_system_timer)
 {
     fluid_sequencer_t *seq;
 
+    if(use_system_timer)
+    {
+        FLUID_LOG(FLUID_WARN, "sequencer: Usage of the system timer has been deprecated!");
+    }
+
     seq = FLUID_NEW(fluid_sequencer_t);
 
     if(seq == NULL)
@@ -172,6 +179,7 @@ delete_fluid_sequencer(fluid_sequencer_t *seq)
  * @param seq Sequencer object
  * @return TRUE if system timer is being used, FALSE otherwise.
  * @since 1.1.0
+ * @deprecated As of fluidsynth 2.1.1 the usage of the system timer has been deprecated.
  */
 int
 fluid_sequencer_get_use_system_timer(fluid_sequencer_t *seq)
@@ -830,7 +838,11 @@ _fluid_seq_queue_process(void *data, unsigned int msec)
 }
 
 /**
- * Advance a sequencer that isn't using the system timer.
+ * Advance a sequencer.
+ *
+ * If you have registered the synthesizer as client (fluid_sequencer_register_fluidsynth()), the synth
+ * will take care of calling fluid_sequencer_process(). Otherwise it is up to the user to
+ * advance the sequencer manually.
  * @param seq Sequencer object
  * @param msec Time to advance sequencer to (absolute time since sequencer start).
  * @since 1.1.0