1 // Copyright (c) 2011 The Chromium Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include "media/audio/win/avrt_wrapper_win.h" 6 7 #include "base/logging.h" 8 9 namespace avrt { 10 11 // Function pointers 12 typedef BOOL (WINAPI *AvRevertMmThreadCharacteristicsFn)(HANDLE); 13 typedef HANDLE (WINAPI *AvSetMmThreadCharacteristicsFn)(LPCWSTR, LPDWORD); 14 typedef BOOL (WINAPI *AvSetMmThreadPriorityFn)(HANDLE, AVRT_PRIORITY); 15 16 HMODULE g_avrt = NULL; 17 AvRevertMmThreadCharacteristicsFn g_revert_mm_thread_characteristics = NULL; 18 AvSetMmThreadCharacteristicsFn g_set_mm_thread_characteristics = NULL; 19 AvSetMmThreadPriorityFn g_set_mm_thread_priority = NULL; 20 21 bool Initialize() { 22 if (!g_set_mm_thread_priority) { 23 // The avrt.dll is available on Windows Vista and later. 24 wchar_t path[MAX_PATH] = {0}; 25 ExpandEnvironmentStrings(L"%WINDIR%\\system32\\avrt.dll", path, 26 arraysize(path)); 27 g_avrt = LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH); 28 if (!g_avrt) 29 return false; 30 31 g_revert_mm_thread_characteristics = 32 reinterpret_cast<AvRevertMmThreadCharacteristicsFn>( 33 GetProcAddress(g_avrt, "AvRevertMmThreadCharacteristics")); 34 g_set_mm_thread_characteristics = 35 reinterpret_cast<AvSetMmThreadCharacteristicsFn>( 36 GetProcAddress(g_avrt, "AvSetMmThreadCharacteristicsW")); 37 g_set_mm_thread_priority = reinterpret_cast<AvSetMmThreadPriorityFn>( 38 GetProcAddress(g_avrt, "AvSetMmThreadPriority")); 39 } 40 41 return (g_avrt && g_revert_mm_thread_characteristics && 42 g_set_mm_thread_characteristics && g_set_mm_thread_priority); 43 } 44 45 bool AvRevertMmThreadCharacteristics(HANDLE avrt_handle) { 46 DCHECK(g_revert_mm_thread_characteristics); 47 return (g_revert_mm_thread_characteristics && 48 g_revert_mm_thread_characteristics(avrt_handle)); 49 } 50 51 HANDLE AvSetMmThreadCharacteristics(const wchar_t* task_name, 52 DWORD* task_index) { 53 DCHECK(g_set_mm_thread_characteristics); 54 return (g_set_mm_thread_characteristics ? 55 g_set_mm_thread_characteristics(task_name, task_index) : NULL); 56 } 57 58 bool AvSetMmThreadPriority(HANDLE avrt_handle, AVRT_PRIORITY priority) { 59 DCHECK(g_set_mm_thread_priority); 60 return (g_set_mm_thread_priority && 61 g_set_mm_thread_priority(avrt_handle, priority)); 62 } 63 64 } // namespace avrt 65
