mirror of
https://gitea.wildfiregames.com/0ad/0ad
synced 2026-06-17 22:03:56 -07:00
43137fef3f
Differential Revision: https://code.wildfiregames.com/D716
Refs 09e974e1cb
Reviewed By: bb
Change in agreement with leper.
This was SVN commit r19899.
117 lines
3.9 KiB
C++
117 lines
3.9 KiB
C++
/* Copyright (C) 2010 Wildfire Games.
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*
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* Permission is hereby granted, free of charge, to any person obtaining
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* a copy of this software and associated documentation files (the
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* "Software"), to deal in the Software without restriction, including
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* without limitation the rights to use, copy, modify, merge, publish,
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* distribute, sublicense, and/or sell copies of the Software, and to
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* permit persons to whom the Software is furnished to do so, subject to
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* the following conditions:
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*
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* The above copyright notice and this permission notice shall be included
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* in all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
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* IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
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* CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
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* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
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* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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*/
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/*
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* Interface for counter implementations
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*/
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#include "precompiled.h"
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#include "lib/sysdep/os/win/whrt/counter.h"
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#include "lib/alignment.h"
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#include "lib/sysdep/cpu.h" // cpu_CAS
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#include "lib/sysdep/os/win/whrt/tsc.h"
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#include "lib/sysdep/os/win/whrt/hpet.h"
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#include "lib/sysdep/os/win/whrt/pmt.h"
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#include "lib/sysdep/os/win/whrt/qpc.h"
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#include "lib/sysdep/os/win/whrt/tgt.h"
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// to add a new counter type, simply include its header here and
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// insert a case in ConstructCounterAt's switch statement.
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//-----------------------------------------------------------------------------
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// create/destroy counters
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/**
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* @param id
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* @param address
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* @param size Maximum allowable size [bytes] of the subclass instance
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* @return pointer to a newly constructed ICounter subclass of type \<id\> at
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* the given address, or 0 iff the ID is invalid.
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**/
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static ICounter* ConstructCounterAt(size_t id, void* address, size_t size)
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{
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// rationale for placement new: see call site.
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// counters are chosen according to the following order. rationale:
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// - TSC must come before QPC and PMT to make sure a bug in the latter on
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// Pentium systems doesn't come up.
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// - PMT works, but is inexplicably slower than QPC on a PIII Mobile.
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// - TGT really isn't as safe as the others, so it should be last.
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// - low-overhead and high-resolution counters are preferred.
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switch(id)
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{
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case 0:
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return CreateCounterHPET(address, size);
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case 1:
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return CreateCounterTSC(address, size);
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case 2:
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return CreateCounterQPC(address, size);
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case 3:
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return CreateCounterPMT(address, size);
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case 4:
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return CreateCounterTGT(address, size);
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default:
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return 0;
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}
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}
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static volatile intptr_t isCounterAllocated;
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ICounter* CreateCounter(size_t id)
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{
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// we placement-new the Counter classes in a static buffer.
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// this is dangerous, but we are careful to ensure alignment. it is
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// unusual and thus bad, but there's also one advantage: we avoid
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// using global operator new before the CRT is initialized (risky).
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//
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// alternatives:
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// - defining as static doesn't work because the ctors (necessary for
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// vptr initialization) run during _cinit, which comes after our
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// first use of them.
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// - using static_calloc isn't possible because we don't know the
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// size until after the alloc / placement new.
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if(!cpu_CAS(&isCounterAllocated, 0, 1))
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DEBUG_WARN_ERR(ERR::LOGIC); // static counter memory is already in use!
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static const size_t memSize = 200;
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static u8 mem[memSize];
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u8* alignedMem = (u8*)Align<16>((uintptr_t)mem);
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const size_t bytesLeft = mem+memSize - alignedMem;
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ICounter* counter = ConstructCounterAt(id, alignedMem, bytesLeft);
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return counter;
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}
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void DestroyCounter(ICounter*& counter)
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{
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ENSURE(counter);
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counter->Shutdown();
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counter->~ICounter(); // must be called due to placement new
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counter = 0;
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isCounterAllocated = 0;
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}
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