Add a stub 'soft' MIDI synth handler

Eventually this one will be used to handle MIDI internally, using our own
mixers and resamplers.

2 files changed, 143 insertions, 0 deletions

diff --git a/Alc/midi/base.h b/Alc/midi/base.h
index 1e1aca4f..a0c20d49 100644
--- a/Alc/midi/base.h
+++ b/Alc/midi/base.h
@@ -118,6 +118,7 @@ static const struct MidiSynthVtable T##_MidiSynth_vtable = {                  \
 }
 
 
+MidiSynth *SSynth_create(ALCdevice *device);
 MidiSynth *FSynth_create(ALCdevice *device);
 MidiSynth *DSynth_create(ALCdevice *device);
 
diff --git a/Alc/midi/soft.c b/Alc/midi/soft.c
new file mode 100644
index 00000000..cef3211b
--- /dev/null
+++ b/Alc/midi/soft.c
@@ -0,0 +1,142 @@
+
+#include "config.h"
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+#include "alMain.h"
+#include "alError.h"
+#include "evtqueue.h"
+#include "alu.h"
+
+#include "midi/base.h"
+
+
+typedef struct SSynth {
+    DERIVE_FROM_TYPE(MidiSynth);
+} SSynth;
+
+static void SSynth_mixSamples(SSynth *self, ALuint SamplesToDo, ALfloat (*restrict DryBuffer)[BUFFERSIZE]);
+
+static void SSynth_Construct(SSynth *self, ALCdevice *device);
+static void SSynth_Destruct(SSynth *self);
+static DECLARE_FORWARD3(SSynth, MidiSynth, ALenum, selectSoundfonts, ALCcontext*, ALsizei, const ALuint*)
+static DECLARE_FORWARD1(SSynth, MidiSynth, void, setGain, ALfloat)
+static DECLARE_FORWARD1(SSynth, MidiSynth, void, setState, ALenum)
+static DECLARE_FORWARD(SSynth, MidiSynth, void, stop)
+static DECLARE_FORWARD(SSynth, MidiSynth, void, reset)
+static void SSynth_update(SSynth *self, ALCdevice *device);
+static void SSynth_process(SSynth *self, ALuint SamplesToDo, ALfloat (*restrict DryBuffer)[BUFFERSIZE]);
+DECLARE_DEFAULT_ALLOCATORS(SSynth)
+DEFINE_MIDISYNTH_VTABLE(SSynth);
+
+
+static void SSynth_Construct(SSynth *self, ALCdevice *device)
+{
+    MidiSynth_Construct(STATIC_CAST(MidiSynth, self), device);
+    SET_VTABLE2(SSynth, MidiSynth, self);
+}
+
+static void SSynth_Destruct(SSynth* UNUSED(self))
+{
+}
+
+
+static void SSynth_update(SSynth* UNUSED(self), ALCdevice* UNUSED(device))
+{
+}
+
+
+static void SSynth_mixSamples(SSynth* UNUSED(self), ALuint UNUSED(SamplesToDo), ALfloat (*restrict DryBuffer)[BUFFERSIZE])
+{
+    (void)DryBuffer;
+}
+
+
+static void SSynth_processQueue(SSynth *self, ALuint64 time)
+{
+    EvtQueue *queue = &STATIC_CAST(MidiSynth, self)->EventQueue;
+
+    while(queue->pos < queue->size && queue->events[queue->pos].time <= time)
+        queue->pos++;
+}
+
+static void SSynth_process(SSynth *self, ALuint SamplesToDo, ALfloat (*restrict DryBuffer)[BUFFERSIZE])
+{
+    MidiSynth *synth = STATIC_CAST(MidiSynth, self);
+    ALenum state = synth->State;
+    ALuint64 curtime;
+    ALuint total = 0;
+
+    if(state == AL_INITIAL)
+        return;
+    if(state != AL_PLAYING)
+    {
+        SSynth_mixSamples(self, SamplesToDo, DryBuffer);
+        return;
+    }
+
+    curtime = MidiSynth_getTime(synth);
+    while(total < SamplesToDo)
+    {
+        ALuint64 time, diff;
+        ALint tonext;
+
+        time = MidiSynth_getNextEvtTime(synth);
+        diff = maxu64(time, curtime) - curtime;
+        if(diff >= MIDI_CLOCK_RES || time == UINT64_MAX)
+        {
+            /* If there's no pending event, or if it's more than 1 second
+             * away, do as many samples as we can. */
+            tonext = INT_MAX;
+        }
+        else
+        {
+            /* Figure out how many samples until the next event. */
+            tonext  = (ALint)((diff*synth->SampleRate + (MIDI_CLOCK_RES-1)) / MIDI_CLOCK_RES);
+            tonext -= total;
+            /* For efficiency reasons, try to mix a multiple of 64 samples
+             * (~1ms @ 44.1khz) before processing the next event. */
+            tonext = (tonext+63) & ~63;
+        }
+
+        if(tonext > 0)
+        {
+            ALuint todo = mini(tonext, SamplesToDo-total);
+            SSynth_mixSamples(self, todo, DryBuffer);
+            total += todo;
+            tonext -= todo;
+        }
+        if(total < SamplesToDo && tonext <= 0)
+            SSynth_processQueue(self, time);
+    }
+
+    synth->SamplesDone += SamplesToDo;
+    synth->ClockBase += (synth->SamplesDone/synth->SampleRate) * MIDI_CLOCK_RES;
+    synth->SamplesDone %= synth->SampleRate;
+}
+
+
+MidiSynth *SSynth_create(ALCdevice *device)
+{
+    SSynth *synth;
+
+    /* This option is temporary. Once this synth is in a more usable state, a
+     * more generic selector should be used. */
+    if(!GetConfigValueBool("midi", "internal-synth", 0))
+    {
+        TRACE("Not using internal MIDI synth\n");
+        return NULL;
+    }
+
+    synth = SSynth_New(sizeof(*synth));
+    if(!synth)
+    {
+        ERR("Failed to allocate SSynth\n");
+        return NULL;
+    }
+    SSynth_Construct(synth, device);
+    return STATIC_CAST(MidiSynth, synth);
+}