学 Win32 汇编[6]: 伪指令 DUP 与数组

声明数组实例:

---

; Test6_1.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib 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

.code

start:

    mov eax, val

    PrintDec eax     ;11

    mov eax, val[4]

    PrintDec eax     ;22

    mov eax, val[8]

    PrintDec eax     ;33

    ret

end start


 
   

上面的例子也可以这样写:

---

; Test6_2.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.data

    val dd 11

        dd 22,33

.code

start:

    mov eax, val[4*0]

    PrintDec eax     ;11

    mov eax, val[4*1]

    PrintDec eax     ;22

    mov eax, val[4*2]

    PrintDec eax     ;33

    ret

end start


 
   

使用伪指令 DUP:

---

; Test6_3.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib 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(?)



.code

start:

    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

    ret

end 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, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib 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

.code

start:

    PrintText 'Hi'

    ret

end 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, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.data?

    v1 dd 4096 dup(?) ;未初始化变量在 .data? 段

.code

start:

    PrintText 'Hi'

    ret

end start


 
   

继续 dup 的例子:

---

; Test6_6.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.data

    val dd 2 dup(1,2,3)

.code

start:

    DumpMem offset val, 24 ;01000000-02000000-03000000-01000000-02000000-03000000

    ret

end start


 
   

嵌套数组:

---

; Test6_7.asm

.386

.model flat, stdcall



include    windows.inc

include    kernel32.inc

include    masm32.inc

include    debug.inc

includelib kernel32.lib

includelib masm32.lib

includelib debug.lib



.data

    val dd 2 dup(3 dup(1,2))

.code

start:

    DumpMem offset val, 48 ;1 2 1 2 1 2  1 2 1 2 1 2

    ret

end start