mirror of
https://gitea.wildfiregames.com/0ad/0ad.git
synced 2026-07-23 01:52:01 +00:00
Ykkrosh
102 lines
2.3 KiB
C++
102 lines
2.3 KiB
C++
/* Copyright (C) 2009 Wildfire Games.
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* This file is part of 0 A.D.
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*
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* 0 A.D. is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* 0 A.D. is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with 0 A.D. If not, see <http://www.gnu.org/licenses/>.
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*/
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/*
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* Timer implementation using timeGetTime
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*/
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// note: WinMM is delay-loaded to avoid dragging it in when this timer
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// implementation isn't used. (this is relevant because its startup is
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// fairly slow)
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#include "precompiled.h"
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#include "tgt.h"
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#include "counter.h"
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#include "lib/sysdep/os/win/win.h"
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#include <mmsystem.h>
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#if MSC_VERSION
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#pragma comment(lib, "winmm.lib")
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#endif
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// "Guidelines For Providing Multimedia Timer Support" claims that
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// speeding the timer up to 2 ms has little impact, while 1 ms
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// causes significant slowdown.
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static const UINT PERIOD_MS = 2;
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class CounterTGT : public ICounter
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{
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public:
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virtual const char* Name() const
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{
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return "TGT";
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}
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LibError Activate()
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{
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// note: timeGetTime is always available and cannot fail.
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MMRESULT ret = timeBeginPeriod(PERIOD_MS);
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debug_assert(ret == TIMERR_NOERROR);
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return INFO::OK;
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}
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void Shutdown()
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{
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timeEndPeriod(PERIOD_MS);
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}
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bool IsSafe() const
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{
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// the only point of criticism is the possibility of falling behind
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// due to lost interrupts. this can happen to any interrupt-based timer
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// and some systems may lack a counter-based timer, so consider TGT
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// 'safe'. note that it is still only chosen when all other timers fail.
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return true;
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}
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u64 Counter() const
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{
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return timeGetTime();
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}
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size_t CounterBits() const
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{
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return 32;
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}
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double NominalFrequency() const
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{
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return 1000.0;
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}
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double Resolution() const
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{
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return PERIOD_MS*1e-3;
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}
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};
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ICounter* CreateCounterTGT(void* address, size_t size)
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{
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debug_assert(sizeof(CounterTGT) <= size);
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return new(address) CounterTGT();
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}
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