为了检测Windows操作系统是32位还是64位的，用MASM32编写了一个调用Windows API函数GetNativeSystemInfo的程序（完整代码附后），GetNativeSystemInfo函数会将指向SYSTEM_INFO结构体的地址存到GetNativeSystemInfo传递的参数中。
微软官网中的STEM_INFO定义为：
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存储了已安装操作系统的处理器体系结构。
访问代码为：
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
需要注意的两点，一是wProcessorArchitecture是word型数据，只有16位。二是MASM32中没有定义PROCESSOR_ARCHITECTURE_ARM64，在微软网官上其值为12。
PROCESSOR_ARCHITECTURE_ARM64 equ 12 ;ARM64
但是在连接程序时总是提示 32or64.asm(54) : error A2006: undefined symbol : u
第54行代码就是
mov ax, (SYSTEM_INFO ptr [eax]).DUMMYUNIONNAME.DUMMYSTRUCTNAME.wProcessorArchitecture
里面并没有使用符号u。
MASM32中的SYSTEM_INFO结构定义存在windows.inc中，居然跟微软官网上的不同：
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结构定义代码中省略了微软官网其中的DUMMYUNIONNAME联合体和DUMMYSTRUCTNAME结构体，难怪使用.DUMMYUNIONNAME.DUMMYSTRUCTNAME.wProcessorArchitecture来访问在连接时会出错，奇怪的是出错信息里没有提示DUMMYUNIONNAME.DUMMYSTRUCTNAME未定义，而是莫明奇妙的u
将第54行代码改为
mov ax, (SYSTEM_INFO ptr [eax]).wProcessorArchitecture
后顺利完成连接，生成了EXE文件，但是更大的麻烦来了……
附完整·代码：
;<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<< ; 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 ;未知体系结构。 _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 "32位",0 g_szGetNativeSystemInfo db "GetNativeSystemInfo", 0 g_szkernel32Dll db "kernel32.dll", 0 g_szFailGetModuleHandle db "GetModuleHandle失败", 0 g_szFailGetProcAddress db "GetProcAddress失败", 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
