barrier/lib/arch/CArchTimeWindows.cpp

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/*
* synergy -- mouse and keyboard sharing utility
* Copyright (C) 2002 Chris Schoeneman, Nick Bolton, Sorin Sbarnea
*
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* This package is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* found in the file COPYING that should have accompanied this file.
*
* This package is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
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*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
// avoid getting a lot a crap from mmsystem.h that we don't need
#define MMNODRV // Installable driver support
#define MMNOSOUND // Sound support
#define MMNOWAVE // Waveform support
#define MMNOMIDI // MIDI support
#define MMNOAUX // Auxiliary audio support
#define MMNOMIXER // Mixer support
#define MMNOJOY // Joystick support
#define MMNOMCI // MCI support
#define MMNOMMIO // Multimedia file I/O support
#define MMNOMMSYSTEM // General MMSYSTEM functions
#define WIN32_LEAN_AND_MEAN
#include "CArchTimeWindows.h"
#include <windows.h>
#include <mmsystem.h>
typedef WINMMAPI DWORD (WINAPI *PTimeGetTime)(void);
static double s_freq = 0.0;
static HINSTANCE s_mmInstance = NULL;
static PTimeGetTime s_tgt = NULL;
//
// CArchTimeWindows
//
CArchTimeWindows::CArchTimeWindows()
{
assert(s_freq == 0.0 || s_mmInstance == NULL);
LARGE_INTEGER freq;
if (QueryPerformanceFrequency(&freq) && freq.QuadPart != 0) {
s_freq = 1.0 / static_cast<double>(freq.QuadPart);
}
else {
// load winmm.dll and get timeGetTime
s_mmInstance = LoadLibrary("winmm");
if (s_mmInstance != NULL) {
s_tgt = (PTimeGetTime)GetProcAddress(s_mmInstance, "timeGetTime");
}
}
}
CArchTimeWindows::~CArchTimeWindows()
{
s_freq = 0.0;
if (s_mmInstance == NULL) {
FreeLibrary(reinterpret_cast<HMODULE>(s_mmInstance));
s_tgt = NULL;
s_mmInstance = NULL;
}
}
double
CArchTimeWindows::time()
{
// get time. we try three ways, in order of descending precision
if (s_freq != 0.0) {
LARGE_INTEGER c;
QueryPerformanceCounter(&c);
return s_freq * static_cast<double>(c.QuadPart);
}
else if (s_tgt != NULL) {
return 0.001 * static_cast<double>(s_tgt());
}
else {
return 0.001 * static_cast<double>(GetTickCount());
}
}