x86_x64.h

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/* Copyright (C) 2022 Wildfire Games.
 *
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 */

/*
 * CPU-specific routines common to 32 and 64-bit x86
 */

#ifndef INCLUDED_X86_X64
#define INCLUDED_X86_X64

#if !ARCH_X86_X64
#error "including x86_x64.h without ARCH_X86_X64=1"
#endif

#if MSC_VERSION
#include <intrin.h> // __rdtsc
#endif

namespace x86_x64 {

/**
 * registers used/returned by cpuid
 **/
#pragma pack(push, 1)   // (allows casting to int*)
struct CpuidRegs
{
    u32 eax;
    u32 ebx;
    u32 ecx;
    u32 edx;
};
#pragma pack(pop)

/**
 * invoke CPUID instruction.
 * @param regs input/output registers.
 *   regs->eax must be set to the desired function.
 *   some functions (e.g. 4) require regs->ecx to be set as well.
 *   rationale: this interface (input/output structure vs. function parameters)
 *     avoids unnecessary copying/initialization if some inputs aren't needed
 *     and allows graceful expansion to functions that require further inputs.
 * @return true on success or false if the sub-function isn't supported.
 **/
bool cpuid(CpuidRegs* regs);

/**
 * CPU vendor.
 * (this is exposed because some CPUID functions are vendor-specific.)
 * (an enum is easier to compare than the original string values.)
 **/
enum Vendors
{
    VENDOR_UNKNOWN,
    VENDOR_INTEL,
    VENDOR_AMD
};

Vendors Vendor();


enum Models
{
    MODEL_NEHALEM_EP     = 0x1A, // Bloomfield (X35xx), Gainestown (X55xx)
    MODEL_NEHALEM_EP_2   = 0x1E, // Clarksfield, Lynnfield (X34xx), Jasper Forest (C35xx, C55xx)
    MODEL_I7_I5          = 0x1F, // similar to 1E; mentioned in 253665-041US, no codename known
    MODEL_CLARKDALE      = 0x25, // Arrandale, Clarkdale (L34xx)
    MODEL_WESTMERE_EP    = 0x2C, // Gulftown (X36xx, X56xx)
    MODEL_NEHALEM_EX     = 0x2E, // Beckton (X75xx)
    MODEL_WESTMERE_EX    = 0x2F, // Gulftown uarch, Beckton package (E7-48xx)
    MODEL_SANDY_BRIDGE   = 0x2A, // (E3-12xx, E5-26xx)
    MODEL_SANDY_BRIDGE_2 = 0x2D, // (E5-26xx, E5-46xx)
};

size_t Model();

size_t Family();


/**
 * @return the colloquial processor generation
 * (5 = Pentium, 6 = Pentium Pro/II/III / K6, 7 = Pentium4 / Athlon, 8 = Core / Opteron)
 **/
size_t Generation();


/**
 * bit indices of CPU capability flags (128 bits).
 * values are defined by IA-32 CPUID feature flags - do not change!
 **/
enum Caps
{
    // standard (ecx) - currently only defined by Intel
    CAP_SSE3            = 0+0,  // Streaming SIMD Extensions 3
    CAP_EST             = 0+7,  // Enhanced Speedstep Technology
    CAP_SSSE3           = 0+9,  // Supplemental Streaming SIMD Extensions 3
    CAP_SSE41           = 0+19, // Streaming SIMD Extensions 4.1
    CAP_SSE42           = 0+20, // Streaming SIMD Extensions 4.2

    // standard (edx)
    CAP_FPU             = 32+0,  // Floating Point Unit
    CAP_TSC             = 32+4,  // TimeStamp Counter
    CAP_MSR             = 32+5,  // Model Specific Registers
    CAP_CMOV            = 32+15, // Conditional MOVe
    CAP_TM_SCC          = 32+22, // Thermal Monitoring and Software Controlled Clock
    CAP_MMX             = 32+23, // MultiMedia eXtensions
    CAP_SSE             = 32+25, // Streaming SIMD Extensions
    CAP_SSE2            = 32+26, // Streaming SIMD Extensions 2
    CAP_HT              = 32+28, // HyperThreading

    // extended (ecx)
    CAP_AMD_CMP_LEGACY  = 64+1,  // N-core and CAP_HT is falsely set

    // extended (edx)
    CAP_AMD_MP          = 96+19,  // MultiProcessing capable; reserved on AMD64
    CAP_AMD_MMX_EXT     = 96+22,
    CAP_AMD_3DNOW_PRO   = 96+30,
    CAP_AMD_3DNOW       = 96+31
};

/**
 * @return whether the CPU supports the indicated Cap / feature flag.
 **/
bool Cap(Caps cap);

void GetCapBits(u32* d0, u32* d1, u32* d2, u32* d3);


//-----------------------------------------------------------------------------
// stateless

/**
 * @return the current value of the TimeStampCounter (a counter of
 * CPU cycles since power-on, which is useful for high-resolution timing
 * but potentially differs between multiple CPUs)
 *
 * notes:
 * - a macro avoids call overhead, which is important for TIMER_ACCRUE.
 * - x64 RDTSC writes to edx:eax and clears the upper halves of rdx and rax.
 **/
#if MSC_VERSION
static inline u64 rdtsc() { return __rdtsc(); }
#else
u64 rdtsc();
#endif

/**
 * trigger a breakpoint inside this function when it is called.
 **/
void DebugBreak();

/**
 * measure the CPU clock frequency via rdtsc and timer_Time.
 * (it follows that this must not be called from WHRT init.)
 * this takes several milliseconds (i.e. much longer than
 * os_cpu_ClockFrequency) but delivers accurate measurements.
 **/
double ClockFrequency();

}   // namespace x86_x64

#endif  // #ifndef INCLUDED_X86_X64