Add a MIDI event queue

In preparation for a MIDI extension.

Alc/evtqueue.h

@@ -0,0 +1,23 @@
+#ifndef AL_EVTQUEUE_H
+#define AL_EVTQUEUE_H
+
+#include "AL/al.h"
+
+typedef struct MidiEvent {
+    ALuint time;
+    ALuint event;
+    ALuint param[2];
+} MidiEvent;
+
+typedef struct EvtQueue {
+    MidiEvent *events;
+    ALsizei pos;
+    ALsizei size;
+    ALsizei maxsize;
+} EvtQueue;
+
+void InitEvtQueue(EvtQueue *queue);
+void ResetEvtQueue(EvtQueue *queue);
+ALenum InsertEvtQueue(EvtQueue *queue, const MidiEvent *evt);
+
+#endif /* AL_EXTQUEUE_H */

CMakeLists.txt

@@ -488,6 +488,7 @@ SET(OPENAL_OBJS  OpenAL32/alAuxEffectSlot.c
                  OpenAL32/alExtension.c
                  OpenAL32/alFilter.c
                  OpenAL32/alListener.c
+                 OpenAL32/alMidi.c
                  OpenAL32/alSource.c
                  OpenAL32/alState.c
                  OpenAL32/alThunk.c

OpenAL32/alMidi.c

@@ -0,0 +1,84 @@
+
+#include "config.h"
+
+#include <stdlib.h>
+#include <string.h>
+#include <limits.h>
+
+#include "evtqueue.h"
+
+
+void InitEvtQueue(EvtQueue *queue)
+{
+    queue->events = NULL;
+    queue->maxsize = 0;
+    queue->size = 0;
+    queue->pos = 0;
+}
+
+void ResetEvtQueue(EvtQueue *queue)
+{
+    free(queue->events);
+    queue->events = NULL;
+    queue->maxsize = 0;
+    queue->size = 0;
+    queue->pos = 0;
+}
+
+ALenum InsertEvtQueue(EvtQueue *queue, const MidiEvent *evt)
+{
+    ALsizei pos;
+
+    if(queue->maxsize == queue->size)
+    {
+        if(queue->pos > 0)
+        {
+            /* Queue has some stale entries, remove them to make space for more
+             * events. */
+            memmove(&queue->events[0], &queue->events[queue->pos],
+                    (queue->size-queue->pos)*sizeof(queue->events[0]));
+            queue->size -= queue->pos;
+            queue->pos = 0;
+        }
+        else
+        {
+            /* Queue is full, double the allocated space. */
+            void *temp = NULL;
+            ALsizei newsize;
+
+            newsize = (queue->maxsize ? (queue->maxsize<<1) : 16);
+            if(newsize > queue->maxsize)
+                temp = realloc(queue->events, newsize * sizeof(queue->events[0]));
+            if(!temp)
+                return AL_OUT_OF_MEMORY;
+
+            queue->events = temp;
+            queue->maxsize = newsize;
+        }
+    }
+
+    pos = queue->pos;
+    if(queue->size > 0)
+    {
+        ALsizei high = queue->size - 1;
+        while(pos < high)
+        {
+            ALsizei mid = pos + (high-pos)/2;
+            if(queue->events[mid].time < evt->time)
+                pos = mid + 1;
+            else
+                high = mid;
+        }
+        while(pos < queue->size && queue->events[pos].time <= evt->time)
+            pos++;
+
+        if(pos < queue->size)
+            memmove(&queue->events[pos+1], &queue->events[pos],
+                    (queue->size-pos)*sizeof(queue->events[0]));
+    }
+
+    queue->events[pos] = *evt;
+    queue->size++;
+
+    return AL_NO_ERROR;
+}