Revert 152406 - Introduce shared_memory_support media target for PPAPI.

media/audio/audio_util.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.
 
 // Software adjust volume of samples, allows each audio stream its own
 // volume without impacting master volume for chrome and other applications.
 
 // Implemented as templates to allow 8, 16 and 32 bit implementations.
 // 8 bit is unsigned and biased by 128.
 
 // TODO(vrk): This file has been running pretty wild and free, and it's likely
 // that a lot of the functions can be simplified and made more elegant. Revisit
 // after other audio cleanup is done. (crbug.com/120319)
 
-#include "media/audio/audio_util.h"
-
 #include <algorithm>
 #include <limits>
 
+#include "base/atomicops.h"
 #include "base/basictypes.h"
 #include "base/logging.h"
+#include "base/shared_memory.h"
 #include "base/time.h"
 #include "media/audio/audio_parameters.h"
+#include "media/audio/audio_util.h"
 #include "media/base/audio_bus.h"
 
 #if defined(OS_MACOSX)
 #include "media/audio/mac/audio_low_latency_input_mac.h"
 #include "media/audio/mac/audio_low_latency_output_mac.h"
 #elif defined(OS_WIN)
 #include "base/command_line.h"
 #include "base/win/windows_version.h"
 #include "media/audio/audio_manager_base.h"
 #include "media/audio/win/audio_low_latency_input_win.h"
 #include "media/audio/win/audio_low_latency_output_win.h"
 #include "media/base/media_switches.h"
 #endif
 
+using base::subtle::Atomic32;
+
+const uint32 kUnknownDataSize = static_cast<uint32>(-1);
+
 namespace media {
 
 // TODO(fbarchard): Convert to intrinsics for better efficiency.
 template<class Fixed>
 static int ScaleChannel(int channel, int volume) {
   return static_cast<int>((static_cast<Fixed>(channel) * volume) >> 16);
 }
 
 template<class Format, class Fixed, int bias>
 static void AdjustVolume(Format* buf_out,
@@ skipping 423 matching lines @@
   // |kMillisecondsPerHardwarePacket| worth of audio data.
   size_t samples = kMinSamplesPerHardwarePacket;
   while (samples <= kMaxSamplesPerHardwarePacket &&
          samples * base::Time::kMillisecondsPerSecond <
          sample_rate * kMillisecondsPerHardwarePacket) {
     samples *= 2;
   }
   return samples;
 }
 
+// When transferring data in the shared memory, first word is size of data
+// in bytes. Actual data starts immediately after it.
+
+uint32 TotalSharedMemorySizeInBytes(uint32 packet_size) {
+  // Need to reserve extra 4 bytes for size of data.
+  return packet_size + sizeof(Atomic32);
+}
+
+uint32 PacketSizeSizeInBytes(uint32 shared_memory_created_size) {
+  return shared_memory_created_size - sizeof(Atomic32);
+}
+
+uint32 GetActualDataSizeInBytes(base::SharedMemory* shared_memory,
+                                uint32 shared_memory_size) {
+  char* ptr = static_cast<char*>(shared_memory->memory()) + shared_memory_size;
+  DCHECK_EQ(0u, reinterpret_cast<size_t>(ptr) & 3);
+
+  // Actual data size stored at the end of the buffer.
+  uint32 actual_data_size =
+      base::subtle::Acquire_Load(reinterpret_cast<volatile Atomic32*>(ptr));
+  return std::min(actual_data_size, shared_memory_size);
+}
+
+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);
+}
+
+void SetUnknownDataSize(base::SharedMemory* shared_memory,
+                        uint32 shared_memory_size) {
+  SetActualDataSizeInBytes(shared_memory, shared_memory_size, kUnknownDataSize);
+}
+
+bool IsUnknownDataSize(base::SharedMemory* shared_memory,
+                       uint32 shared_memory_size) {
+  char* ptr = static_cast<char*>(shared_memory->memory()) + shared_memory_size;
+  DCHECK_EQ(0u, reinterpret_cast<size_t>(ptr) & 3);
+
+  // Actual data size stored at the end of the buffer.
+  uint32 actual_data_size =
+      base::subtle::Acquire_Load(reinterpret_cast<volatile Atomic32*>(ptr));
+  return actual_data_size == kUnknownDataSize;
+}
+
 #if defined(OS_WIN)
 
 bool IsWASAPISupported() {
   // Note: that function correctly returns that Windows Server 2003 does not
   // support WASAPI.
   return base::win::GetVersion() >= base::win::VERSION_VISTA;
 }
 
 int NumberOfWaveOutBuffers() {
   // Use 4 buffers for Vista, 3 for everyone else:
   //  - The entire Windows audio stack was rewritten for Windows Vista and wave
   //    out performance was degraded compared to XP.
   //  - The regression was fixed in Windows 7 and most configurations will work
   //    with 2, but some (e.g., some Sound Blasters) still need 3.
   //  - Some XP configurations (even multi-processor ones) also need 3.
   return (base::win::GetVersion() == base::win::VERSION_VISTA) ? 4 : 3;
 }
 
 #endif
 
 }  // namespace media