Add generic ring buffer methods

Alc/alcRing.c

@@ -0,0 +1,118 @@
+/**
+ * OpenAL cross platform audio library
+ * Copyright (C) 1999-2007 by authors.
+ * This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Library General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Library General Public License for more details.
+ *
+ * You should have received a copy of the GNU Library General Public
+ *  License along with this library; if not, write to the
+ *  Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+ *  Boston, MA  02111-1307, USA.
+ * Or go to http://www.gnu.org/copyleft/lgpl.html
+ */
+
+#include <string.h>
+#include <stdlib.h>
+
+#include "config.h"
+
+#include "alMain.h"
+
+
+struct RingBuffer {
+    ALubyte *mem;
+
+    ALsizei frame_size;
+    ALsizei length;
+    ALint read_pos;
+    ALint write_pos;
+
+    CRITICAL_SECTION cs;
+};
+
+
+RingBuffer *CreateRingBuffer(ALsizei frame_size, ALsizei length)
+{
+    RingBuffer *ring = calloc(1, sizeof(*ring));
+    if(ring)
+    {
+        ring->frame_size = frame_size;
+        ring->length = length+1;
+        ring->write_pos = 1;
+        ring->mem = malloc((length+1)*frame_size);
+        if(!ring->mem)
+        {
+            free(ring);
+            ring = NULL;
+        }
+
+        InitializeCriticalSection(&ring->cs);
+    }
+    return ring;
+}
+
+void DestroyRingBuffer(RingBuffer *ring)
+{
+    if(ring)
+    {
+        DeleteCriticalSection(&ring->cs);
+        free(ring->mem);
+        free(ring);
+    }
+}
+
+ALsizei RingBufferSize(RingBuffer *ring)
+{
+    return (ring->read_pos+1-ring->write_pos+ring->length) % ring->length;
+}
+
+void WriteRingBuffer(RingBuffer *ring, const ALubyte *data, ALsizei len)
+{
+    int remain = ring->length - ring->write_pos;
+
+    EnterCriticalSection(&ring->cs);
+
+    if((ring->write_pos-ring->read_pos+ring->length)%ring->length < len)
+        ring->read_pos = ((ring->write_pos+len) % ring->length) + 1;
+
+    if(remain < len)
+    {
+        memcpy(ring->mem+(ring->write_pos*ring->frame_size), data, remain*ring->frame_size);
+        memcpy(ring->mem, data+(remain*ring->frame_size), (len-remain)*ring->frame_size);
+    }
+    else
+        memcpy(ring->mem+(ring->write_pos*ring->frame_size), data, len*ring->frame_size);
+
+    ring->write_pos += len;
+    ring->write_pos %= ring->length;
+
+    LeaveCriticalSection(&ring->cs);
+}
+
+void ReadRingBuffer(RingBuffer *ring, ALubyte *data, ALsizei len)
+{
+    int remain = ring->length - ring->read_pos;
+
+    EnterCriticalSection(&ring->cs);
+
+    if(remain < len)
+    {
+        memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), remain*ring->frame_size);
+        memcpy(data+(remain*ring->frame_size), ring->mem, (len-remain)*ring->frame_size);
+    }
+    else
+        memcpy(data, ring->mem+(ring->read_pos*ring->frame_size), len*ring->frame_size);
+
+    ring->read_pos += len;
+    ring->read_pos %= ring->length;
+
+    LeaveCriticalSection(&ring->cs);
+}
+

CMakeLists.txt

@@ -172,6 +172,7 @@ SET(OPENAL_OBJS  OpenAL32/alBuffer.c
 SET(ALC_OBJS  Alc/ALc.c
               Alc/ALu.c
               Alc/alcConfig.c
+              Alc/alcRing.c
               Alc/alcThread.c
 )
 

OpenAL32/Include/alMain.h

@@ -188,6 +188,13 @@ ALCvoid ProcessContext(ALCcontext *context);
 ALvoid *StartThread(ALuint (*func)(ALvoid*), ALvoid *ptr);
 ALuint StopThread(ALvoid *thread);
 
+typedef struct RingBuffer RingBuffer;
+RingBuffer *CreateRingBuffer(ALsizei frame_size, ALsizei length);
+void DestroyRingBuffer(RingBuffer *ring);
+ALsizei RingBufferSize(RingBuffer *ring);
+void WriteRingBuffer(RingBuffer *ring, const ALubyte *data, ALsizei len);
+void ReadRingBuffer(RingBuffer *ring, ALubyte *data, ALsizei len);
+
 void ReadALConfig(void);
 void FreeALConfig(void);
 const char *GetConfigValue(const char *blockName, const char *keyName, const char *def);