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