学 Win32 汇编[6]: 伪指令 DUP 与数组

声明数组实例:

; Test6_1.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    ;声明并初始化有三个元素的 DWORD 数组; 该数组每个元素是 4 字节?   val dd 11,22,33.codestart:?   mov eax, val?   PrintDec eax?    ;11?   mov eax, val[4]?   PrintDec eax?    ;22?   mov eax, val[8]?   PrintDec eax?    ;33?   retend start

上面的例子也可以这样写:

; Test6_2.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data?   val dd 11?   ?   dd 22,33.codestart:?   mov eax, val[4*0]?   PrintDec eax?    ;11?   mov eax, val[4*1]?   PrintDec eax?    ;22?   mov eax, val[4*2]?   PrintDec eax?    ;33?   retend start

使用伪指令 DUP:

; Test6_3.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data    ;声明有三个元素的 DWORD 数组, 并把每个元素初始化为 6?   v1 dd 3 dup(6)    ;声明有三个元素的 DWORD 数组, 无初始化; 对全局变量, 没有初始化的将用 0 填充?   v2 dd 3 dup(?).data?    ;声明有三个元素的 DWORD 数组?   v3 dd 3 dup(?).codestart:?   DumpMem offset v1, 12  ;06 00 00 00 - 06 00 00 00 - 06 00 00 00?   DumpMem offset v2, 12  ;00 00 00 00 - 00 00 00 00 - 00 00 00 00?   DumpMem offset v3, 12  ;00 00 00 00 - 00 00 00 00 - 00 00 00 00?   retend start

现在可以区别未初始化的变量在 .data 段和 .data? 的区别:

; Test6_4.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data?   v1 dd 4096 dup(?) ;未初始化变量在 .data 段, 生成的 exe 文件会根据大小分配内存.codestart:?   PrintText 'Hi'?   retend start; ------------------------------------------------------; 上面的程序的 exe 是 18944 字节; 下面的程序的 exe 是 2560 字节; 它们刚好相差 4096*4 个字节; 结论: 不需要初始化的变量应该声明在 .data? 段; ------------------------------------------------------; Test6_5.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data??   v1 dd 4096 dup(?) ;未初始化变量在 .data? 段.codestart:?   PrintText 'Hi'?   retend start

继续 dup 的例子:

; Test6_6.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data?   val dd 2 dup(1,2,3).codestart:?   DumpMem offset val, 24 ;01000000-02000000-03000000-01000000-02000000-03000000?   retend start

嵌套数组:

; Test6_7.asm.386.model flat, stdcallinclude    windows.incinclude    kernel32.incinclude    masm32.incinclude    debug.incincludelib kernel32.libincludelib masm32.libincludelib debug.lib.data?   val dd 2 dup(3 dup(1,2)).codestart:?   DumpMem offset val, 48 ;1 2 1 2 1 2  1 2 1 2 1 2?   retend start