為了檢測Windows操作系統是32位還是64位的，用MASM32編寫了一個調用Windows API函數GetNativeSystemInfo的程序（完整代碼附后），GetNativeSystemInfo函數會將指向SYSTEM_INFO結構體的地址存到GetNativeSystemInfo傳遞的參數中。

微軟官網中的STEM_INFO定義為：

typedef struct _SYSTEM_INFO {
  union {
    DWORD dwOemId;
    struct {
      WORD wProcessorArchitecture;
      WORD wReserved;
    } DUMMYSTRUCTNAME;
  } DUMMYUNIONNAME;
  DWORD     dwPageSize;
  LPVOID    lpMinimumApplicationAddress;
  LPVOID    lpMaximumApplicationAddress;
  DWORD_PTR dwActiveProcessorMask;
  DWORD     dwNumberOfProcessors;
  DWORD     dwProcessorType;
  DWORD     dwAllocationGranularity;
  WORD      wProcessorLevel;
  WORD      wProcessorRevision;
} SYSTEM_INFO, *LPSYSTEM_INFO;

SYSTEM_INFO中的wProcessorArchitecture存儲了已安裝操作系統的處理器體系結構。

訪問代碼為：???????????????

                 mov  eax, g_lpSI
                 mov  ax,  (SYSTEM_INFO ptr [eax]).DUMMYUNIONNAME.DUMMYSTRUCTNAME.wProcessorArchitecture
                 and  eax, 0ffffh
                 .if (eax==PROCESSOR_ARCHITECTURE_AMD64) || (eax==PROCESSOR_ARCHITECTURE_IA64) || (eax==PROCESSOR_ARCHITECTURE_ARM64)
                     mov eax, OFFSET g_sz64Bit
                 .else
                     mov eax, OFFSET g_sz32Bit
                 .endif

需要注意的兩點，一是wProcessorArchitecture是word型數據，只有16位。二是MASM32中沒有定義PROCESSOR_ARCHITECTURE_ARM64，在微軟網官上其值為12。

PROCESSOR_ARCHITECTURE_ARM64   equ 12     ;ARM64

但是在連接程序時總是提示 32or64.asm(54) : error A2006: undefined symbol : u

第54行代碼就是
?

mov  ax,  (SYSTEM_INFO ptr [eax]).DUMMYUNIONNAME.DUMMYSTRUCTNAME.wProcessorArchitecture

里面并沒有使用符號u。

MASM32中的SYSTEM_INFO結構定義存在windows.inc中，居然跟微軟官網上的不同：

SYSTEM_INFO STRUCT
  wProcessorArchitecture        WORD       ?
  wReserved                     WORD       ?
  dwPageSize                    DWORD      ?
  lpMinimumApplicationAddress   DWORD      ?
  lpMaximumApplicationAddress   DWORD      ?
  dwActiveProcessorMask         DWORD      ?
  dwNumberOfProcessors          DWORD      ?
  dwProcessorType               DWORD      ?
  dwAllocationGranularity       DWORD      ?
  wProcessorLevel               WORD       ?
  wProcessorRevision            WORD       ?
SYSTEM_INFO ENDS

MASM32中的SYSTEM_INFO結構定義代碼中省略了微軟官網其中的DUMMYUNIONNAME聯合體和DUMMYSTRUCTNAME結構體，難怪使用.DUMMYUNIONNAME.DUMMYSTRUCTNAME.wProcessorArchitecture來訪問在連接時會出錯，奇怪的是出錯信息里沒有提示DUMMYUNIONNAME.DUMMYSTRUCTNAME未定義，而是莫明奇妙的u

將第54行代碼改為

mov  ax,  (SYSTEM_INFO ptr [eax]).wProcessorArchitecture

后順利完成連接，生成了EXE文件，但是更大的麻煩來了……

附完整·代碼：文章來源地址http://www.zghlxwxcb.cn/news/detail-726620.html

;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
; 32or64.asm
;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

.586
.model     flat, stdcall
option     casemap:none
include    \masm32\include\windows.inc
include    \masm32\include\kernel32.inc
includelib \masm32\lib\kernel32.lib
include    \masm32\include\user32.inc
includelib \masm32\lib\user32.lib

;sssssssssssssssssssssssssssssssssssssss
;.const
;sssssssssssssssssssssssssssssssssssssss
;PROCESSOR_ARCHITECTURE_INTEL   equ 0      ;x86
;PROCESSOR_ARCHITECTURE_ARM     equ 5      ;ARM
;PROCESSOR_ARCHITECTURE_IA64    equ 6      ;基于 Intel Itanium 的
;PROCESSOR_ARCHITECTURE_AMD64   equ 9      ;x64 (AMD 或 Intel)
PROCESSOR_ARCHITECTURE_ARM64   equ 12     ;ARM64
;PROCESSOR_ARCHITECTURE_UNKNOWN equ 0ffffh ;未知體系結構。


_SYSTEM_INFO STRUCT
   UNION
     dwOemId DWORD ?
     STRUCT
        wProcessorArchitecture        WORD       ?
        wReserved                     WORD       ?
     ENDS
  ENDS
  dwPageSize                    DWORD      ?
  lpMinimumApplicationAddress   DWORD      ?
  lpMaximumApplicationAddress   DWORD      ?
  dwActiveProcessorMask         DWORD      ?
  dwNumberOfProcessors          DWORD      ?
  dwProcessorType               DWORD      ?
  dwAllocationGranularity       DWORD      ?
  wProcessorLevel               WORD       ?
  wProcessorRevision            WORD       ?
_SYSTEM_INFO ENDS

;sssssssssssssssssssssssssssssssssssssss
.data
;sssssssssssssssssssssssssssssssssssssss
g_szCaption               db    "Windows",0
g_sz32Bit                 db    "32位",0
g_sz64Bit                 db    "64位",0
g_szGetNativeSystemInfo   db    "GetNativeSystemInfo", 0
g_szkernel32Dll           db    "kernel32.dll", 0
g_szFailGetModuleHandle   db    "GetModuleHandle失敗", 0
g_szFailGetProcAddress    db    "GetProcAddress失敗", 0
g_lpfnGetNativeSystemInfo dword ?
g_lpSI                    dword ?  ; SYSTEM_INFO


;sssssssssssssssssssssssssssssssssssssss
.code
;sssssssssssssssssssssssssssssssssssssss
start:
      invoke GetModuleHandle, OFFSET g_szkernel32Dll
      .if    eax==NULL
             mov eax, OFFSET g_szFailGetModuleHandle
      .else
             invoke GetProcAddress, eax, OFFSET g_szGetNativeSystemInfo
             .IF eax==NULL
                 mov eax, OFFSET g_szFailGetProcAddress
             .ELSE
                 mov  g_lpfnGetNativeSystemInfo, eax
                 push OFFSET g_lpSI
                 call g_lpfnGetNativeSystemInfo
                 mov  eax, g_lpSI
                 mov  ax, (SYSTEM_INFO ptr [eax]).wProcessorArchitecture
                 and  eax, 0ffffh 
                 ;mov  eax, (_SYSTEM_INFO ptr [eax]).dwOemId
                 .if (eax==PROCESSOR_ARCHITECTURE_IA64) || (eax==PROCESSOR_ARCHITECTURE_AMD64) || (eax==PROCESSOR_ARCHITECTURE_ARM64)
                     mov eax, OFFSET g_sz64Bit
                 .else
                     mov eax, OFFSET g_sz32Bit
                 .endif
             .ENDIF
      .endif
      invoke MessageBox, NULL, eax, OFFSET g_szCaption, MB_OK
      invoke ExitProcess, NULL
end start

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