使用Visual Studio 2010的32位C ++到64位C ++

Question

I recently want to convert a 32-bit C++ project to 64-bit, but I am stuck with the first try. Could you point out any suggestions/checklist/points when converting 32-bit C++ to 64-bit in VS (like converting 32-bit Delphi to 64-bit).

int GetVendorID_0(char *pVendorID,int iLen)
{
#ifdef WIN64  // why WIN64 is not defined switching to Active (x64) ?
    // what to put here?
#else
    DWORD   dwA,dwB,dwC,dwD;
    __asm
    {
        PUSHAD
        MOV     EAX,0
        CPUID   //CPUID(EAX=0),
        MOV     dwA,EAX
        MOV     dwC,ECX
        MOV     dwD,EDX
        MOV     dwB,EBX
        POPAD
    }
    memset( pVendorID,      0,iLen);
    memcpy( pVendorID,      &dwB,4);
    memcpy(&pVendorID[4],   &dwD,4);
    memcpy(&pVendorID[8],   &dwC,4);
    return dwA;
#endif
}

Answer 1

Microsoft's compilers (some of them, anyway) have a flag to point out at least some common problems where code will probably need modification to work as 64-bit code.

As far as your GetVendorID_0 function goes, I'd use Microsoft's _cpuid function, something like this:

int GetVendorID_0(char *pVendorID, int iLen) { 
    DWORD data[4];

    _cpuid(0, data);
    memcpy(pVendorID, data+1, 12);
    return data[0];
}

That obviously doesn't replace all instances of inline assembly language. You choices are fairly simple (though not necessarily easy). One is to find an intrinsic like this to do the job. The other is to move the assembly code into a separate file and link it with your code in C++ (and learn the x64 calling convention). The third is to simply forego what you're doing now, and write the closest equivalent you can with more portable code.