Win32 compilation [6]: pseudo-command DUP and array

Declare an array instance:

 
; Test6_1.asm.386.model flat, stdcallinclude windows. incinclude kernel32.incinclude masm32.incinclude debug. incincludelib kernel32.libincludelib masm32.libincludelib debug. lib. data; declare and initialize a DWORD array with three elements. Each element of the array is 4-byte Val DD, 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

  
 

The preceding example can also be written as follows:

 
; 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

  
 

Use the pseudo command DUP:

 
; Test6_3.asm.386.model flat, stdcallinclude windows. incinclude kernel32.incinclude masm32.incinclude debug. incincludelib kernel32.libincludelib masm32.libincludelib debug. lib. data; declare a DWORD array with three elements, and initialize each element to 6 V1 DD 3 DUP (6); declare a DWORD array with three elements without initialization; for global variables, if not initialized, V2 DD 3 DUP (?) will be filled with 0 (?). Data? Declare the DWORD array V3 DD 3 DUP (?) with three elements (?). Codestart: dumpmem offset V1, 12; 06 00 00 00-06 00 00-06 00 00 00 00 dumpmem offset V2, 12; 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 00 retend start

  
 

Now we can distinguish uninitialized variables in the. Data Segment From. Data? Differences:

; ‑Flat, stdcallinclude windows. incinclude kernel32.incinclude masm32.incinclude Debug. incincludelib kernel32.libincludelib masm32.libincludelib Debug. Lib. Data V1 dd 4096 DUP (?) ; The uninitialized variable is in the. Data segment. The generated EXE file will allocate the memory according to the size. codestart: printtext 'Hi' retend start; ------------------------------------------; The aboveProgramThe EXE of the program is 18944 bytes, And the EXE of the program below is 2560 bytes. The difference is exactly 4096*4 bytes. Conclusion: variables that do not need to be initialized should be declared in. Data? Segment; break; kernel flat, stdcallinclude windows. incinclude kernel32.incinclude masm32.incinclude Debug. incincludelib kernel32.libincludelib masm32.libincludelib Debug. Lib. Data? V1 dd 4096 DUP (?) ; The variable is not initialized in. Data? Segment. codestart: printtext 'Hi' retend start

  
 

Example of continued DUP:

; 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

  
 

Nested array:

 
; 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 2 2 1 2 2 retend start