Fixes audio for Native Client, and other fixes...

- SDL_NaClMount, SDL_NaClUmount
- Default mounting of https at / in SDL's main function
- More documentation in README-nacl.txt

src/audio/nacl/SDL_naclaudio.c

@@ -49,15 +49,24 @@ static void nacl_audio_callback(void* samples, uint32_t buffer_size, PP_TimeDelt
     SDL_AudioDevice* _this = (SDL_AudioDevice*) data;
     
     SDL_LockMutex(private->mutex);
-    /*if (private->opened) {*/
-    SDL_memset(samples, _this->spec.silence, buffer_size);
-    SDL_LockMutex(_this->mixer_lock);
-    (*_this->spec.callback)(_this->spec.userdata, (Uint8*)samples, buffer_size);
-    SDL_UnlockMutex(_this->mixer_lock);
-    /*} else {
+
+    if (_this->enabled && !_this->paused) {
+        if (_this->convert.needed) {
+            SDL_LockMutex(_this->mixer_lock);
+            (*_this->spec.callback) (_this->spec.userdata,
+                                     (Uint8 *) _this->convert.buf,
+                                     _this->convert.len);
+            SDL_UnlockMutex(_this->mixer_lock);
+            SDL_ConvertAudio(&_this->convert);
+            SDL_memcpy(samples, _this->convert.buf, _this->convert.len_cvt);
+        } else {
+            SDL_LockMutex(_this->mixer_lock);
+            (*_this->spec.callback) (_this->spec.userdata, (Uint8 *) samples, buffer_size);
+            SDL_UnlockMutex(_this->mixer_lock);
+        }
+    } else {
         SDL_memset(samples, 0, buffer_size);
-    }*/
-    SDL_UnlockMutex(private->mutex);
+    }
     
     return;
 }
@@ -93,6 +102,9 @@ NACLAUD_OpenDevice(_THIS, const char *devname, int iscapture) {
         PP_AUDIOSAMPLERATE_44100, 
         SAMPLE_FRAME_COUNT);
     
+    /* Calculate the final parameters for this audio specification */
+    SDL_CalculateAudioSpec(&_this->spec);
+    
     private->audio = ppb_audio->Create(
         instance,
         ppb_audiocfg->CreateStereo16Bit(instance, PP_AUDIOSAMPLERATE_44100, _this->spec.samples),

src/filesystem/nacl/SDL_sysfilesytem.c

@@ -0,0 +1,59 @@
+/*
+  Simple DirectMedia Layer
+  Copyright (C) 1997-2014 Sam Lantinga <slouken@libsdl.org>
+
+  This software is provided 'as-is', without any express or implied
+  warranty.  In no event will the authors be held liable for any damages
+  arising from the use of this software.
+
+  Permission is granted to anyone to use this software for any purpose,
+  including commercial applications, and to alter it and redistribute it
+  freely, subject to the following restrictions:
+
+  1. The origin of this software must not be misrepresented; you must not
+     claim that you wrote the original software. If you use this software
+     in a product, an acknowledgment in the product documentation would be
+     appreciated but is not required.
+  2. Altered source versions must be plainly marked as such, and must not be
+     misrepresented as being the original software.
+  3. This notice may not be removed or altered from any source distribution.
+*/
+#include "../../SDL_internal.h"
+#include "SDL_error.h"
+#include "SDL_filesystem.h"
+
+#ifdef SDL_FILESYSTEM_NACL
+
+/* SDL_RWops on NACL are implemented using nacl_io, and require mount points
+ * to be established before actual file operations are performed
+ * 
+ * Ref: https://developers.google.com/native-client/dev/devguide/coding/nacl_io
+ */
+
+int 
+SDL_NaClMount(const char* source, const char* target, const char* filesystemtype, 
+          unsigned long mountflags, const void *data) {
+    return mount(source, target, filesystemtype, mountflags, data);
+}
+
+int 
+SDL_NaClUmount(const char *target) {
+    return umount(target);
+}
+
+
+char *
+SDL_GetBasePath(void)
+{
+    SDL_Unsupported();
+    return NULL;
+}
+
+char *
+SDL_GetPrefPath(const char *org, const char *app)
+{
+    SDL_Unsupported();
+    return NULL;
+}
+
+#endif /* __NACL__ */

src/main/nacl/SDL_nacl_main.c

@@ -24,6 +24,7 @@
 
 /* Include the SDL main definition header */
 #include "SDL_main.h"
+#include "SDL_system.h"
 
 #include "ppapi_simple/ps_main.h"
 #include "ppapi_simple/ps_event.h"
@@ -64,6 +65,18 @@ nacl_main(int argc, char *argv[])
         }
     }
     
+    /* Do a default httpfs mount on /, 
+     * apps can override this by unmounting / 
+     * and remounting with the desired configuration
+     */
+    SDL_NaClUmount("/");
+    SDL_NaClMount(
+        "",  /* source */
+        "/",  /* target */
+        "httpfs",  /* filesystemtype */
+        0,  /* mountflags */
+        "");  /* data specific to the html5fs type */
+    
     /* Everything is ready, start the user main function */
     SDL_SetMainReady();
     status = SDL_main(argc, argv);