forked from mirrors/0ad
janwas
c3a42633fa
also improved filtering of the frame delta times. while at it, improved interface of whrt backends to avoid leaking implementation details. This was SVN commit r6401.
116 lines
2.6 KiB
C++
116 lines
2.6 KiB
C++
/**
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* =========================================================================
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* File : pmt.cpp
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* Project : 0 A.D.
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* Description : Timer implementation using ACPI PM timer
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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 "pmt.h"
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#include "counter.h"
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#include "lib/sysdep/os/win/win.h"
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#include "lib/sysdep/acpi.h"
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#include "lib/sysdep/os/win/mahaf.h"
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#include "lib/bits.h"
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#pragma pack(push,1)
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struct FADT
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{
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AcpiTable header;
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u8 unused[40];
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u32 pmTimerPortAddress;
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u8 unused2[32];
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u32 flags;
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};
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#pragma pack(pop)
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static const u32 TMR_VAL_EXT = Bit<u32>(8);
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//-----------------------------------------------------------------------------
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class CounterPMT : public ICounter
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{
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public:
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CounterPMT()
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: m_portAddress(0xFFFF)
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{
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}
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virtual const char* Name() const
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{
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return "PMT";
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}
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LibError Activate()
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{
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// mahaf is needed for port I/O.
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if(!mahaf_Init())
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return ERR::FAIL; // NOWARN (no Administrator privileges)
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if(!acpi_Init())
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return ERR::FAIL; // NOWARN (happens on Win2k; see mahaf_IsPhysicalMappingDangerous)
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// (note: it's called FADT, but the signature is "FACP")
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const FADT* fadt = (const FADT*)acpi_GetTable("FACP");
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if(!fadt)
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WARN_RETURN(ERR::NO_SYS);
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m_portAddress = u16_from_larger(fadt->pmTimerPortAddress);
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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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acpi_Shutdown();
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mahaf_Shutdown();
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}
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bool IsSafe() const
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{
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// the PMT has one issue: "Performance counter value may unexpectedly
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// leap forward" (Q274323). This happens on some buggy Pentium-era
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// systems under heavy PCI bus load. We are clever and observe that
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// the TSC implementation would be used on such systems (because it
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// has higher precedence and is safe on P5 CPUs), so the PMT is fine
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// in general.
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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 mahaf_ReadPort32(m_portAddress);
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}
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size_t CounterBits() const
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{
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// (see previous acpi_GetTable call)
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const FADT* fadt = (const FADT*)acpi_GetTable("FACP");
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debug_assert(fadt); // Activate made sure FADT is available
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const size_t counterBits = (fadt->flags & TMR_VAL_EXT)? 32 : 24;
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return counterBits;
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}
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double NominalFrequency() const
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{
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return (double)PMT_FREQ;
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}
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double Resolution() const
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{
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return 1.0 / PMT_FREQ;
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}
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private:
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u16 m_portAddress;
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};
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ICounter* CreateCounterPMT(void* address, size_t size)
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{
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debug_assert(sizeof(CounterPMT) <= size);
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return new(address) CounterPMT();
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}
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