Level : intermediate

OS : windows
Language : ASM

How to use interrupts directly instead of using the windows API.

Well, first what we need to do is to find out how the API works.
In my tutorial, we will take SetCursorPos() as an example.
First, you need to write a program that calls SetCursorPos().

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 .code
 start:
 invoke SetCursorPos, 100, 100 ;voila!
 invoke ExitProcess, 0
 end start
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00401000 >/$ 6A 64          PUSH 64                                  ; /Y = 64 (100.)
00401002  |. 6A 64          PUSH 64                                  ; |X = 64 (100.)
00401004  |. E8 07000000    CALL           ; SetCursorPos
00401009  |. 6A 00          PUSH 0                                   ; /ExitCode = 0
0040100B  . E8 06000000    CALL          ; ExitProcess
00401010   $-FF25 08204000  JMP DWORD PTR DS:[>;  user32.SetCursorPos
00401016   .-FF25 00204000  JMP DWORD PTR DS:[;  KERNEL32.ExitProcess
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77E3577A > 6A 5F            PUSH 5F
77E3577C   FF7424 0C        PUSH DWORD PTR SS:[ESP+C]
77E35780   FF7424 0C        PUSH DWORD PTR SS:[ESP+C]
77E35784   E8 A3EBFDFF      CALL user32.77E1432C
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77E1432C   B8 3A110000      MOV EAX,113A
77E14331   8D5424 04        LEA EDX,DWORD PTR SS:[ESP+4]
77E14335   CD 2E            INT 2E
77E14337   C2 0C00          RETN 0C
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0012FFAC  64 00 00 00 64 00 00 00  d...d...
0012FFB4  5F 00 00 00              _...
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 thePos STRUCT
 x dd 0
 y dd 0
 z dd 5Fh
 thePos ENDS

 .data
 myApp db "BoR0's Native Syscaller",0
 succ  db "Successfully set cursor!", 0
 erro  db "Error while setting cursor!", 0

 mystr thePos <>

 .code
 start:
 mov mystr.y, 300
 mov mystr.x, 300

 mov eax, 113Ah
 mov edx, offset mystr
 int 2Eh

 .IF eax == 1
 invoke MessageBox, 0, ADDR succ, ADDR myApp, MB_OK+MB_ICONINFORMATION
 .ELSE
 invoke MessageBox, 0, ADDR erro, ADDR myApp, MB_OK+MB_ICONERROR
 .ENDIF

 invoke ExitProcess,0

 end start
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