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https://gitea.wildfiregames.com/0ad/0ad
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7a5655edde
cpu.cpp: avoided the need for wrapper functions by calling the OS-specific function directly (declared in central header, implemented in the platform's cpp file) avoid the need for init in cpu and ia32 via if(!init) Init() pattern. optimized memcpy now requires SSE support remove error-prone CAS macro; replace with cpu_CAS config: no longer require inline asm for float->int conversions lib_error: remove special-case in CHECK_ERR for windows (no longer needed) This was SVN commit r5365.
108 lines
3.2 KiB
C++
108 lines
3.2 KiB
C++
/**
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* =========================================================================
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* File : counter.cpp
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* Project : 0 A.D.
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* Description : Interface for counter implementations
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* =========================================================================
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*/
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// license: GPL; see lib/license.txt
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#include "precompiled.h"
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#include "counter.h"
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#include "lib/bits.h"
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#include "lib/allocators.h"
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#include "tsc.h"
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#include "hpet.h"
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#include "pmt.h"
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#include "qpc.h"
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#include "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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* @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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* @param size maximum allowable size [bytes] of the subclass instance
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**/
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static ICounter* ConstructCounterAt(uint 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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#include "lib/nommgr.h" // MMGR interferes with placement new
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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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debug_assert(sizeof(CounterHPET) <= size);
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return new(address) CounterHPET();
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case 1:
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debug_assert(sizeof(CounterTSC) <= size);
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return new(address) CounterTSC();
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case 2:
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debug_assert(sizeof(CounterQPC) <= size);
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return new(address) CounterQPC();
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case 3:
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debug_assert(sizeof(CounterPMT) <= size);
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return new(address) CounterPMT();
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case 4:
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debug_assert(sizeof(CounterTGT) <= size);
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return new(address) CounterTGT();
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default:
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return 0;
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}
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#include "lib/mmgr.h"
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}
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static volatile uintptr_t isCounterAllocated;
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ICounter* CreateCounter(uint 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("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*)round_up((uintptr_t)mem, 16);
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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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debug_assert(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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