c++中的__asm__错误

Question

我试图用以下代码读取cpuid信息，但它不起作用。我使用的是Visual Studio 2010:

#include "stdafx.h"
#include <stdio.h>
int main()
{
  int a, b;
  for (a = 0; a < 5; a++)
  {
    __asm__("cpuid"
            :"=a"(b)                 // EAX into b (output)
            :"0"(a)                  // a into EAX (input)
            :"%ebx","%ecx","%edx");  // clobbered registers
    printf("The code %i gives %in", a, b);
  }
  return 0;
}

上面是这样写的:

'project_scs.exe': Loaded 'C:Usersrares992DocumentsVisual Studio 2010Projectsproject_scsDebugproject_scs.exe', Symbols loaded.
'project_scs.exe': Loaded 'C:WindowsSysWOW64ntdll.dll', Symbols loaded (source information stripped).
'project_scs.exe': Loaded 'C:WindowsSysWOW64kernel32.dll', Symbols loaded (source information stripped).
'project_scs.exe': Loaded 'C:WindowsSysWOW64KernelBase.dll', Symbols loaded (source information stripped).
'project_scs.exe': Loaded 'C:WindowsSysWOW64msvcp100d.dll', Symbols loaded.
'project_scs.exe': Loaded 'C:WindowsSysWOW64msvcr100d.dll', Symbols loaded.
The thread 'Win32 Thread' (0x2190) has exited with code -1073741510 (0xc000013a).
The program '[8828] project_scs.exe: Native' has exited with code -1073741510 (0xc000013a).

有谁能告诉我怎么做才能让它运行吗?由于

Answer 1

主要问题是:您使用了用于GCC的AT&T语法。然而，Visual Studio需要英特尔语法。看看下面的例子，看看里面的链接:

#include <stdio.h>
#include <intrin.h>
#define EAX 0
#define EBX 1
#define ECX 2
#define EDX 3
int main ( void )
{
    int exx[4], a;
    // http://msdn.microsoft.com/en-us/library/4ks26t93%28v=vs.100%29.aspx
    puts ("Using VC inline assembler:");
    for (a = 0; a < 5; a++)
    {
        __asm
        {
            xor ecx, ecx            // needed for a=4
            mov eax, a
            cpuid
            mov exx[EAX], eax
        }
        printf("The code %i gives %08Xn", a, exx[EAX]);
    }
    // http://msdn.microsoft.com/en-us/library/vstudio/hskdteyh%28v=vs.100%29.aspx
    puts ("Using VC intrinsics:");
    for (a = 0; a < 5; a++)
    {
        __cpuid(exx, a);
         printf("The code %i gives %08Xn", a, exx[EAX]);
    }
    return 0;
}

Answer 2

下面是我使用的。它应该与MSVC、ICC、GCC和Clang一起工作。

static inline void cpuid (int output[4], int functionnumber) {  
#if defined (_MSC_VER) || defined (__INTEL_COMPILER)       // Microsoft or Intel compiler, intrin.h included
    __cpuidex(output, functionnumber, 0);                  // intrinsic function for CPUID
#elif defined(__GNUC__) || defined(__clang__)              // use inline assembly, Gnu/AT&T syntax
   int a, b, c, d;
   __asm("cpuid" : "=a"(a),"=b"(b),"=c"(c),"=d"(d) : "a"(functionnumber),"c"(0) : );
   output[0] = a;
   output[1] = b;
   output[2] = c;
   output[3] = d;
#else                                                      // unknown platform. try inline assembly with masm/intel syntax
    __asm {
        mov eax, functionnumber
        xor ecx, ecx
        cpuid;
        mov esi, output
        mov [esi],    eax
        mov [esi+4],  ebx
        mov [esi+8],  ecx
        mov [esi+12], edx
    }
#endif
}