Modify the PPB_Audio_Shared code for NaCl.

ppapi/shared_impl/ppb_audio_shared.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ppapi/shared_impl/ppb_audio_shared.h"
 
 #include "base/logging.h"
 #include "ppapi/shared_impl/ppapi_globals.h"
 
 using base::subtle::Atomic32;
 
 namespace ppapi {
 
+#if defined(OS_NACL)
+namespace {
+// Because this is static, the function pointers will be NULL initially.
+PP_ThreadFunctions thread_functions;
+}
+#endif  // defined(OS_NACL)
+
 // FIXME: The following two functions (TotalSharedMemorySizeInBytes,
 // SetActualDataSizeInBytes) are copied from audio_util.cc.
 // Remove these functions once a minimal media library is provided for them.
 // code.google.com/p/chromium/issues/detail?id=123203
 
 uint32 TotalSharedMemorySizeInBytes(uint32 packet_size) {
   // Need to reserve extra 4 bytes for size of data.
   return packet_size + sizeof(Atomic32);
 }
 
 void SetActualDataSizeInBytes(base::SharedMemory* shared_memory,
                               uint32 shared_memory_size,
                               uint32 actual_data_size) {
   char* ptr = static_cast<char*>(shared_memory->memory()) + shared_memory_size;
   DCHECK_EQ(0u, reinterpret_cast<size_t>(ptr) & 3);
 
   // Set actual data size at the end of the buffer.
   base::subtle::Release_Store(reinterpret_cast<volatile Atomic32*>(ptr),
                               actual_data_size);
 }
 
 const int PPB_Audio_Shared::kPauseMark = -1;
 
 PPB_Audio_Shared::PPB_Audio_Shared()
     : playing_(false),
       shared_memory_size_(0),
+#if defined(OS_NACL)
+      thread_id_(),

[dmichael (off chromium), 2012/07/25 03:12:26]

It would be clearer to put 0 in explicitly.

[bbudge, 2012/07/25 12:04:37]

I copied it from the SRPC code because I thought it nicely captured the
"don't-care" nature of this. OK. Done.

+      thread_active_(false),
+#endif
       callback_(NULL),
       user_data_(NULL) {
 }
 
 PPB_Audio_Shared::~PPB_Audio_Shared() {
   StopThread();
 }
 
 void PPB_Audio_Shared::SetCallback(PPB_Audio_Callback callback,
                                    void* user_data) {
   callback_ = callback;
   user_data_ = user_data;
 }
 
 void PPB_Audio_Shared::SetStartPlaybackState() {
   DCHECK(!playing_);
+#if !defined(OS_NACL)
   DCHECK(!audio_thread_.get());
-
+#else
+  DCHECK(!thread_active_);
+#endif
   // If the socket doesn't exist, that means that the plugin has started before
   // the browser has had a chance to create all the shared memory info and
   // notify us. This is a common case. In this case, we just set the playing_
   // flag and the playback will automatically start when that data is available
   // in SetStreamInfo.
   playing_ = true;
   StartThread();
 }
 
 void PPB_Audio_Shared::SetStopPlaybackState() {
@@ skipping 16 matching lines @@
       "Failed to map shared memory for PPB_Audio_Shared.");
   }
 
   StartThread();
 }
 
 void PPB_Audio_Shared::StartThread() {
   // Don't start the thread unless all our state is set up correctly.
   if (!playing_ || !callback_ || !socket_.get() || !shared_memory_->memory())
     return;
+  // Clear contents of shm buffer before starting audio thread. This will
+  // prevent a burst of static if for some reason the audio thread doesn't
+  // start up quickly enough.
+  memset(shared_memory_->memory(), 0, shared_memory_size_);
+#if !defined(OS_NACL)
   DCHECK(!audio_thread_.get());
   audio_thread_.reset(new base::DelegateSimpleThread(
       this, "plugin_audio_thread"));
   audio_thread_->Start();
+#else
+  // Use NaCl's special API for IRT code that creates threads that call back
+  // into user code.
+  if (NULL == thread_functions.thread_create ||
+      NULL == thread_functions.thread_join)
+    return;
+
+  int result = thread_functions.thread_create(&thread_id_, CallRun, this);
+  DCHECK_EQ(result, 0);
+  thread_active_ = true;
+#endif
 }
 
 void PPB_Audio_Shared::StopThread() {
   // Shut down the socket to escape any hanging |Receive|s.
   if (socket_.get())
     socket_->Shutdown();
+  #if !defined(OS_NACL)
   if (audio_thread_.get()) {
     audio_thread_->Join();
     audio_thread_.reset();
   }
+#else
+  if (thread_active_) {
+    int result = thread_functions.thread_join(thread_id_);
+    DCHECK_EQ(0, result);
+    thread_active_ = false;
+  }
+#endif
 }
 
+#if defined(OS_NACL)
+// static
+void PPB_Audio_Shared::SetThreadFunctions(
+    const struct PP_ThreadFunctions* functions) {
+  DCHECK(thread_functions.thread_create == NULL);
+  DCHECK(thread_functions.thread_join == NULL);
+  thread_functions = *functions;
+}
+
+// static
+void PPB_Audio_Shared::CallRun(void* self) {
+  PPB_Audio_Shared* audio = static_cast<PPB_Audio_Shared*>(self);
+  audio->Run();
+}
+#endif
+
 void PPB_Audio_Shared::Run() {
   int pending_data;
   void* buffer = shared_memory_->memory();
 
   while (sizeof(pending_data) ==
       socket_->Receive(&pending_data, sizeof(pending_data)) &&
       pending_data != kPauseMark) {
     callback_(buffer, shared_memory_size_, user_data_);
 
     // Let the host know we are done.
     SetActualDataSizeInBytes(shared_memory_.get(), shared_memory_size_,
         shared_memory_size_);
   }
 }
 
 }  // namespace ppapi