Add external API for audio driver.

Makefile

@@ -98,7 +98,7 @@ ifeq ($(HAVE_XML), 1)
 endif
 
 ifeq ($(HAVE_DYLIB), 1)
-   OBJ += gfx/ext.o
+   OBJ += gfx/ext.o audio/ext.o
    LIBS += -ldl
 endif
 

Makefile.win32

@@ -82,7 +82,7 @@ ifeq ($(HAVE_FBO), 1)
 endif
 
 ifeq ($(HAVE_DYLIB), 1)
-   OBJ += gfx/ext.o
+   OBJ += gfx/ext.o audio/ext.o
 endif
 
 ifneq ($(V),1)

Makefile.win64

@@ -82,7 +82,7 @@ ifeq ($(HAVE_FBO), 1)
 endif
 
 ifeq ($(HAVE_DYLIB), 1)
-   OBJ += gfx/ext.o
+   OBJ += gfx/ext.o audio/ext.o
 endif
 
 

audio/ext.c

@@ -0,0 +1,149 @@
+/*  SSNES - A Super Nintendo Entertainment System (SNES) Emulator frontend for libsnes.
+ *  Copyright (C) 2010-2011 - Hans-Kristian Arntzen
+ *
+ *  Some code herein may be based on code found in BSNES.
+ * 
+ *  SSNES is free software: you can redistribute it and/or modify it under the terms
+ *  of the GNU General Public License as published by the Free Software Found-
+ *  ation, either version 3 of the License, or (at your option) any later version.
+ *
+ *  SSNES 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 General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with SSNES.
+ *  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "ext/ssnes_audio.h"
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdint.h>
+#include "driver.h"
+#include "dynamic.h"
+#include "general.h"
+#include <sys/types.h>
+
+typedef struct audio_ext
+{
+   dylib_t lib;
+   const ssnes_audio_driver_t *driver;
+   void *handle;
+   bool is_float;
+} audio_ext_t;
+
+static void audio_ext_free(void *data)
+{
+   audio_ext_t *ext = data;
+   if (ext)
+   {
+      if (ext->driver && ext->handle)
+         ext->driver->free(ext->handle);
+      if (ext->lib)
+         dylib_close(ext->lib);
+      free(ext);
+   }
+}
+
+static void* audio_ext_init(const char *device, int rate, int latency)
+{
+   if (!(*g_settings.audio.external_driver))
+   {
+      SSNES_ERR("Please define an external audio driver.\n");
+      return NULL;
+   }
+
+   audio_ext_t *ext = calloc(1, sizeof(*ext));
+   if (!ext)
+      return NULL;
+
+   ext->lib = dylib_load(g_settings.audio.external_driver);
+   if (!ext->lib)
+   {
+      SSNES_ERR("Failed to load external library \"%s\"\n", g_settings.audio.external_driver);
+      goto error;
+   }
+
+   const ssnes_audio_driver_t* (*plugin_load)(void) = dylib_proc(ext->lib, "ssnes_audio_driver_init");
+
+   if (!plugin_load)
+   {
+      SSNES_ERR("Failed to find symbol \"ssnes_audio_driver_init\" in plugin.\n");
+      goto error;
+   }
+
+   ext->driver = plugin_load();
+   if (!ext->driver)
+   {
+      SSNES_ERR("Received invalid driver from plugin.\n");
+      goto error;
+   }
+
+   ssnes_audio_driver_info_t info = {
+      .device = device,
+      .sample_rate = rate,
+      .latency = latency
+   };
+
+   ext->handle = ext->driver->init(&info);
+   if (!ext->handle)
+   {
+      SSNES_ERR("Failed to init audio driver.\n");
+      goto error;
+   }
+
+   return ext;
+
+error:
+   audio_ext_free(ext);
+   return NULL;
+}
+
+static ssize_t audio_ext_write(void *data, const void *buf, size_t size)
+{
+   audio_ext_t *ext = data;
+   unsigned frame_size = ext->is_float ? (2 * sizeof(float)) : (2 * sizeof(int16_t));
+   size /= frame_size;
+
+   int ret = ext->driver->write(ext->handle, buf, size);
+   if (ret < 0)
+      return -1;
+   return ret * frame_size;
+}
+
+static bool audio_ext_start(void *data)
+{
+   audio_ext_t *ext = data;
+   return ext->driver->start(ext->handle);
+}
+
+static bool audio_ext_stop(void *data)
+{
+   audio_ext_t *ext = data;
+   return ext->driver->stop(ext->handle);
+}
+
+static void audio_ext_set_nonblock_state(void *data, bool toggle)
+{
+   audio_ext_t *ext = data;
+   ext->driver->set_nonblock_state(ext->handle, toggle);
+}
+
+static bool audio_ext_use_float(void *data)
+{
+   audio_ext_t *ext = data;
+   ext->is_float = ext->driver->use_float(ext->handle);
+   return ext->is_float;
+}
+
+
+const audio_driver_t audio_ext = {
+   .init = audio_ext_init,
+   .write = audio_ext_write,
+   .stop = audio_ext_stop,
+   .start = audio_ext_start,
+   .set_nonblock_state = audio_ext_set_nonblock_state,
+   .use_float = audio_ext_use_float,
+   .free = audio_ext_free,
+   .ident = "ext"
+};

audio/ext/ssnes_audio.h

@@ -0,0 +1,110 @@
+/////
+// API header for external SSNES audio driver plugins.
+//
+//
+
+#ifndef __SSNES_AUDIO_DRIVER_PLUGIN_H
+#define __SSNES_AUDIO_DRIVER_PLUGIN_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#ifdef _WIN32
+#ifdef SSNES_DLL_IMPORT
+#define SSNES_API_EXPORT __declspec(dllimport) 
+#else
+#define SSNES_API_EXPORT __declspec(dllexport) 
+#endif
+#define SSNES_API_CALLTYPE __cdecl
+#else
+#define SSNES_API_EXPORT
+#define SSNES_API_CALLTYPE
+#endif
+
+#define SSNES_TRUE 1
+#define SSNES_FALSE 0
+#define SSNES_OK 1
+#define SSNES_ERROR 0
+
+#define SSNES_API_VERSION 1
+
+typedef struct ssnes_audio_driver_info
+{
+   // A hint for a subdevice of the audio driver.
+   // This is driver independent, and not relevant for all
+   // audio drivers. I.e. ALSA driver might use "hw:0",
+   // OSS "/dev/audio", etc.
+   const char *device;
+
+   // Audio sample rate.
+   unsigned sample_rate;
+
+   // Maximum audio latency requested for output,
+   // measured in milliseconds.
+   // If driver is not able to provide this latency, it can
+   // be disregarded.
+   unsigned latency;
+} ssnes_audio_driver_info_t;
+
+typedef struct ssnes_audio_driver
+{
+   // Initializes the device.
+   void* (*init)(const ssnes_audio_driver_info_t *info);
+
+   // Write data in buffer to audio driver.
+   // A frame here is defined as one combined sample of left and right
+   // channels. (I.e. 44.1kHz, 16-bit stereo has 88.2k samples/s, and
+   // 44.1k frames/s.)
+   //
+   // Samples are interleaved in format LRLRLRLRLR ...
+   // If the driver returns true in use_float(), a floating point
+   // format will be used, with range [-1.0, 1.0].
+   // If not, signed 16-bit samples in native byte ordering will be used.
+   // 
+   // This function returns the number of frames successfully written.
+   // If an error occurs, -1 should be returned.
+   // Note that non-blocking behavior that cannot write at this time
+   // should return 0 as returning -1 will terminate the driver.
+   //
+   // Unless said otherwise with set_nonblock_state(), all writes
+   // are blocking, and it should block till it has written all frames.
+   int (*write)(void *data, const void *buffer, unsigned frames);
+
+   // Temporarily pauses the audio driver.
+   int (*stop)(void *data);
+
+   // Resumes audio driver from the paused state.
+   int (*start)(void *data);
+
+   // If state is true, nonblocking operation is assumed.
+   // This is typically used for fast-forwarding. If driver cannot
+   // implement nonblocking writes, this can be disregarded, but should
+   // log a message to stderr.
+   void (*set_nonblock_state)(void *data, int state);
+
+   // Stops and frees the audio driver.
+   void (*free)(void *data);
+
+   // If true is returned, the audio driver is capable of using
+   // floating point data. This will likely increase performance as the
+   // resampler unit uses floating point. The sample range is
+   // [-1.0, 1.0].
+   int (*use_float)(void *data);
+
+   // Human readable identification string for the driver.
+   const char *ident;
+
+   // Must be set to SSNES_API_VERSION.
+   // Used for detecting API mismatch.
+   int api_version;
+} ssnes_audio_driver_t;
+
+SSNES_API_EXPORT const ssnes_audio_driver_t* SSNES_API_CALLTYPE
+   ssnes_audio_driver_init(void);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

config.def.h

@@ -56,6 +56,7 @@
 #define AUDIO_SDL 8
 #define AUDIO_XAUDIO 9
 #define AUDIO_PULSE 10
+#define AUDIO_EXT 15
 ////////////////////////
 #define INPUT_SDL 7
 #define INPUT_X 12
@@ -91,6 +92,8 @@
 #define AUDIO_DEFAULT_DRIVER AUDIO_RSOUND
 #elif defined(HAVE_ROAR)
 #define AUDIO_DEFAULT_DRIVER AUDIO_ROAR
+#elif defined(HAVE_DYLIB)
+#define AUDIO_DEFAULT_DRIVER AUDIO_EXT
 #else
 #error "Need at least one audio driver!"
 #endif

driver.c

@@ -56,6 +56,9 @@ static const audio_driver_t *audio_drivers[] = {
 #ifdef HAVE_PULSE
    &audio_pulse,
 #endif
+#ifdef HAVE_DYLIB
+   &audio_ext,
+#endif
 };
 
 static const video_driver_t *video_drivers[] = {

driver.h

@@ -154,6 +154,7 @@ extern const audio_driver_t audio_jack;
 extern const audio_driver_t audio_sdl;
 extern const audio_driver_t audio_xa;
 extern const audio_driver_t audio_pulse;
+extern const audio_driver_t audio_ext;
 extern const video_driver_t video_gl;
 extern const video_driver_t video_xvideo;
 extern const video_driver_t video_sdl;

general.h

@@ -106,6 +106,7 @@ struct settings
       int src_quality;
 
       char dsp_plugin[256];
+      char external_driver[256];
    } audio;
 
    struct

settings.c

@@ -83,6 +83,9 @@ static void set_defaults(void)
       case AUDIO_PULSE:
          def_audio = "pulse";
          break;
+      case AUDIO_EXT:
+         def_audio = "ext";
+         break;
       default:
          break;
    }
@@ -315,6 +318,7 @@ static void parse_config_file(void)
 #ifdef HAVE_DYLIB
    CONFIG_GET_STRING(video.filter_path, "video_filter");
    CONFIG_GET_STRING(video.external_driver, "video_external_driver");
+   CONFIG_GET_STRING(audio.external_driver, "audio_external_driver");
 #endif
 
 #if defined(HAVE_CG) || defined(HAVE_XML)

ssnes.cfg

@@ -99,9 +99,12 @@
 # When altering audio_in_rate on-the-fly, define by how much each time.
 # audio_rate_step = 0.25
 
-# Audio driver backend. Depending on configuration possible candidates are: alsa, pulse, oss, jack, rsound, roar, openal, sdl and xaudio
+# Audio driver backend. Depending on configuration possible candidates are: alsa, pulse, oss, jack, rsound, roar, openal, sdl, xaudio and ext (external driver).
 # audio_driver =
 
+# Path to external audio driver using the SSNES audio driver API.
+# audio_external_driver =
+
 # Override the default audio device the audio_driver uses. This is driver dependant. E.g. ALSA wants a PCM device, OSS wants a path (e.g. /dev/dsp), Jack wants portnames (e.g. system:playback1,system:playback_2), and so on ...
 # audio_device =