cpuinfo.c

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/*
 * PROJECT:     ReactOS Kernel
 * LICENSE:     MIT (https://spdx.org/licenses/MIT)
 * PURPOSE:     Routines for x86 / x64 CPU information gathering
 * COPYRIGHT:   Copyright 2026 Timo Kreuzer <timo.kreuzer@reactos.org>
 */
 
/* INCLUDES *****************************************************************/
 
#include <ntoskrnl.h>
#include <x86x64/Cpuid.h>
#define NDEBUG
#include <debug.h>
 
/* FUNCTIONS *****************************************************************/
 
VOID
NTAPI
KiGetCpuVendorString(
    _Out_writes_z_(CPU_VENDOR_STR_LEN) CHAR VendorString[CPU_VENDOR_STR_LEN])
{
    CPUID_SIGNATURE_REGS Signature;
 
    /* Get the Vendor string */
    __cpuid(&Signature.AsInt32[0], CPUID_SIGNATURE);
 
    /* Copy and null-terminate it */
    *(ULONG*)&VendorString[0] = *(ULONG*)&Signature.SignatureScrambled[0];
    *(ULONG*)&VendorString[4] = *(ULONG*)&Signature.SignatureScrambled[8];
    *(ULONG*)&VendorString[8] = *(ULONG*)&Signature.SignatureScrambled[4];
    VendorString[12] = 0;
}
 
CPU_VENDORS
NTAPI
KiIdentifyCpuVendor(
    _In_reads_z_(CPU_VENDOR_STR_LEN) const CHAR VendorString[CPU_VENDOR_STR_LEN])
{
    /* Identify the CPU vendor */
    if (!strcmp(VendorString, "GenuineIntel") ||
        !strcmp(VendorString, "GenuineIotel")) // Intel Xeon E3-1231 v3
    {
        return CPU_INTEL;
    }
    else if (!strcmp(VendorString, "AuthenticAMD") ||
             !strcmp(VendorString, "HygonGenuine"))
    {
        return CPU_AMD;
    }
    else if (!strcmp(VendorString, "CentaurHauls") ||
             !strcmp(VendorString, "  Shanghai  "))
    {
        return CPU_VIA; // == CPU_CENTAUR
    }
#ifdef _M_I386
    else if (!strcmp(VendorString, "CyrixInstead"))
    {
        return CPU_CYRIX;
    }
    else if (!strcmp(VendorString, "GenuineTMx86"))
    {
        return CPU_TRANSMETA;
    }
    else if (!strcmp(VendorString, "RiseRiseRise"))
    {
        return CPU_RISE;
    }
#endif // _M_I386
 
    return CPU_UNKNOWN;
}
 
VOID
NTAPI
KiGetCpuSignature(
    _Out_ PUSHORT Family,
    _Out_ PUSHORT Model,
    _Out_ PUSHORT Stepping)
{
    CPUID_VERSION_INFO_REGS VersionInfo;
 
    /* Get the CPUID */
    __cpuid(VersionInfo.AsInt32, 1);
 
    /* Get the family */
    *Family = VersionInfo.Eax.Bits.FamilyId;
    if (VersionInfo.Eax.Bits.FamilyId == 15)
    {
        *Family += VersionInfo.Eax.Bits.ExtendedFamilyId;
    }
 
    /* Get the model */
    *Model = VersionInfo.Eax.Bits.Model;
    if ((VersionInfo.Eax.Bits.FamilyId == 6) ||
        (VersionInfo.Eax.Bits.FamilyId == 15))
    {
        /* For Family < 15, AMD documents extended model as RAZ (reads as zero) */
        *Model |= VersionInfo.Eax.Bits.ExtendedModelId << 4;
    }
 
    /* Get the stepping */
    *Stepping = VersionInfo.Eax.Bits.SteppingId;
}