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> Windows > [solved] How to call wsprintf in xp via fasmg ? |
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uor99 25 Sep 2016, 12:57
Please read the following replies.
Last edited by uor99 on 26 Sep 2016, 07:39; edited 1 time in total |
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25 Sep 2016, 12:57 |
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uor99 26 Sep 2016, 07:37
Thanks for your help, revolution ! I got it at last.
Last edited by uor99 on 28 Sep 2016, 11:10; edited 1 time in total |
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26 Sep 2016, 07:37 |
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sinsi 26 Sep 2016, 09:08
Quote: Note It is important to note that wsprintf uses the C calling convention (_cdecl), rather than the standard call (_stdcall) calling convention. As a result, it is the responsibility of the calling process to pop arguments off the stack, and arguments are pushed on the stack from right to left. |
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26 Sep 2016, 09:08 |
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uor99 27 Sep 2016, 13:43
sinsi, you are right. I am eager to know whether there are any errors in the above codes. Please give us the correct codes.
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27 Sep 2016, 13:43 |
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AsmGuru62 27 Sep 2016, 14:34
every PUSH results in:
Code: SUB ESP, 4 So to bring stack back after the call you need this: Code: ADD ESP, 4*<# of PUSH-es> In your case 4 parameters pushed, so: Code: CALL [wsprintfA] ADD ESP,16 If you're calling few of these in sequence you can optimize: Code: ; ; push values for 1st call ; CALL [wsprintfA] ; ; push values for 2nd call ; CALL [wsprintfA] ; ; push values for 3rd call ; CALL [wsprintfA] ADD ESP, <room for all pushes> I am not sure however if FASM will properly handle the variables declared as local. I am talking about a case where you access your locals in the middle of your call: Code: PUSH param1 PUSH param2 ; ; Access locals here ; PUSH param3 CALL [wsprintfA] I believe FASM has a macro for using the calls to these types of functions. The macro pushes parameters AND restores stack in one line, and even then I am not sure if locals will be properly handled. |
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27 Sep 2016, 14:34 |
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revolution 27 Sep 2016, 15:08
The standard fasm macros use EBP for locals so it is not affected by pushes, pops or any other ESP manipulations.
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27 Sep 2016, 15:08 |
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Tomasz Grysztar 27 Sep 2016, 15:33
There is no officially made proc.inc for fasmg yet, but the basic stdcall/ccall macros are very easy to make, I'm writing them as I type here:
Code: macro stdcall proc,args& iterate arg, args indx 1+%%-% pushd arg end iterate call proc end macro macro ccall proc,args& local size size = 0 iterate arg, args indx 1+%%-% pushd arg size = size + 4 end iterate call proc if size add esp,size end if end macro macro invoke proc,args& stdcall [proc],args end macro macro cinvoke proc,args& ccall [proc],args end macro With these macros your code could look like: Code: start: call main invoke ExitProcess,0 main: cinvoke wsprintfA,buf,fmt,hi,88 invoke MessageBoxA,0,buf,hi,0 ret |
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27 Sep 2016, 15:33 |
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uor99 28 Sep 2016, 22:48
;Thanks for all of you ! It works well.
Code: include '80386.inc' include 'format/format.inc' format PE GUI entry start macro stdcall proc,args& iterate arg, args indx 1+%%-% pushd arg end iterate call proc end macro macro ccall proc,args& local size size = 0 iterate arg, args indx 1+%%-% pushd arg size = size + 4 end iterate call proc if size add esp,size end if end macro macro invoke proc,args& stdcall [proc],args end macro macro cinvoke proc,args& ccall [proc],args end macro section '.idata' import data readable writeable dd 0,0,0,RVA kernel_name,RVA kernel_table dd 0,0,0,RVA user_name,RVA user_table dd 0,0,0,0,0 ; kernel_name db 'KERNEL32.DLL',0 user_name db 'USER32.DLL',0 ; kernel_table: ExitProcess dd rva _ExitProcess CreateFile dd rva _CreateFileA ReadFile dd rva _ReadFile WriteFile dd rva _WriteFile CloseHandle dd rva _CloseHandle SetFilePointer dd rva _SetFilePointer GetCommandLine dd rva _GetCommandLineA GetEnvironmentVariable dd rva _GetEnvironmentVariable GetStdHandle dd rva _GetStdHandle VirtualAlloc dd rva _VirtualAlloc VirtualFree dd rva _VirtualFree GetTickCount dd rva _GetTickCount GetSystemTime dd rva _GetSystemTime GlobalMemoryStatus dd rva _GlobalMemoryStatus dd 0 _ExitProcess dw 0 db 'ExitProcess',0 _CreateFileA dw 0 db 'CreateFileA',0 _ReadFile dw 0 db 'ReadFile',0 _WriteFile dw 0 db 'WriteFile',0 _CloseHandle dw 0 db 'CloseHandle',0 _SetFilePointer dw 0 db 'SetFilePointer',0 _GetCommandLineA dw 0 db 'GetCommandLineA',0 _GetEnvironmentVariable dw 0 db 'GetEnvironmentVariableA',0 _GetStdHandle dw 0 db 'GetStdHandle',0 _VirtualAlloc dw 0 db 'VirtualAlloc',0 _VirtualFree dw 0 db 'VirtualFree',0 _GetTickCount dw 0 db 'GetTickCount',0 _GetSystemTime dw 0 db 'GetSystemTime',0 _GlobalMemoryStatus dw 0 db 'GlobalMemoryStatus',0 ; user_table: MessageBoxA dd RVA _MessageBoxA wsprintfA dd RVA _wsprintfA dd 0 ; _MessageBoxA dw 0 db 'MessageBoxA',0 _wsprintfA dw 0 db 'wsprintfA',0 ; section '.reloc' fixups data readable discardable section '.text' code readable executable start: call main push 0 call [ExitProcess] ; main: cinvoke wsprintfA,buf,fmt,88,hi invoke MessageBoxA,0,buf,hi,0 ret section '.data' data readable writeable ;needed by wsprintf fmt DB "%d, %s !",0 hi DB "hi",0 buf DB 22 DUP(?) |
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28 Sep 2016, 22:48 |
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