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// Copyright (c) 2011 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 "media/audio/win/avrt_wrapper_win.h"
#include "base/logging.h"
namespace avrt {
// Function pointers
typedef BOOL (WINAPI *AvRevertMmThreadCharacteristicsFn)(HANDLE);
typedef HANDLE (WINAPI *AvSetMmThreadCharacteristicsFn)(LPCWSTR, LPDWORD);
typedef BOOL (WINAPI *AvSetMmThreadPriorityFn)(HANDLE, AVRT_PRIORITY);
HMODULE g_avrt = NULL;
AvRevertMmThreadCharacteristicsFn g_revert_mm_thread_characteristics = NULL;
AvSetMmThreadCharacteristicsFn g_set_mm_thread_characteristics = NULL;
AvSetMmThreadPriorityFn g_set_mm_thread_priority = NULL;
bool Initialize() {
if (!g_set_mm_thread_priority) {
// The avrt.dll is available on Windows Vista and later.
wchar_t path[MAX_PATH] = {0};
ExpandEnvironmentStrings(L"%WINDIR%\\system32\\avrt.dll", path,
arraysize(path));
g_avrt = LoadLibraryExW(path, NULL, LOAD_WITH_ALTERED_SEARCH_PATH);
if (!g_avrt)
return false;
g_revert_mm_thread_characteristics =
reinterpret_cast<AvRevertMmThreadCharacteristicsFn>(
GetProcAddress(g_avrt, "AvRevertMmThreadCharacteristics"));
g_set_mm_thread_characteristics =
reinterpret_cast<AvSetMmThreadCharacteristicsFn>(
GetProcAddress(g_avrt, "AvSetMmThreadCharacteristicsW"));
g_set_mm_thread_priority = reinterpret_cast<AvSetMmThreadPriorityFn>(
GetProcAddress(g_avrt, "AvSetMmThreadPriority"));
}
return (g_avrt && g_revert_mm_thread_characteristics &&
g_set_mm_thread_characteristics && g_set_mm_thread_priority);
}
bool AvRevertMmThreadCharacteristics(HANDLE avrt_handle) {
DCHECK(g_revert_mm_thread_characteristics);
return (g_revert_mm_thread_characteristics &&
g_revert_mm_thread_characteristics(avrt_handle));
}
HANDLE AvSetMmThreadCharacteristics(const wchar_t* task_name,
DWORD* task_index) {
DCHECK(g_set_mm_thread_characteristics);
return (g_set_mm_thread_characteristics ?
g_set_mm_thread_characteristics(task_name, task_index) : NULL);
}
bool AvSetMmThreadPriority(HANDLE avrt_handle, AVRT_PRIORITY priority) {
DCHECK(g_set_mm_thread_priority);
return (g_set_mm_thread_priority &&
g_set_mm_thread_priority(avrt_handle, priority));
}
} // namespace avrt
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