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flat assembler > Compiler Internals > [fasmg] windows lseek

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Mike Gonta



Joined: 26 Dec 2010
Posts: 211
Code:
invoke SetFilePointer, ebx, eax, [position_high], ecx
The third parameter to SetFilePointer should be a pointer to position_high or NULL.

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Mike Gonta
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Post 25 May 2017, 21:56
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 6867
Location: Kraków, Poland
Thank you for spotting this. It shows that I never tested it with really large files.
Post 25 May 2017, 22:06
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Mike Gonta



Joined: 26 Dec 2010
Posts: 211
Code:
lseek: ; in: ebx = file handle, cl = method, edx:eax = offset ; out: edx:eax = new offset from the beginning of file, cf set on error ; preserves: ebx, esi, edi movzx ecx,cl mov [position_high],edx invoke SetFilePointer,ebx,eax,position_high,ecx cmp eax,-1 je interface_error mov edx,[position_high] clc retn
MSDN wrote:
If the return value is INVALID_SET_FILE_POINTER and if lpDistanceToMoveHigh is non-NULL, an application must call
GetLastError to determine whether or not the function has succeeded or failed.
SetFilePointerEx is similar to the Linux sys_llseek parameters and might be a better fit.

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Mike Gonta
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Post 26 May 2017, 12:16
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 6867
Location: Kraków, Poland
Good catch! Corrected, thank you again.
Post 26 May 2017, 14:12
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Mike Gonta



Joined: 26 Dec 2010
Posts: 211
With SetFilePointerEx it's similar to fasmg (Linux) lseek.
Code:
position qd ? lseek: ; in: ebx = file handle, cl = method, edx:eax = offset ; out: edx:eax = new offset from the beginning of file, cf set on error ; preserves: ebx, esi, edi movzx ecx,cl invoke SetFilePointerEx,ebx,eax,edx,position,ecx test eax,eax jz interface_error mov eax, [position] mov edx, [position+4] clc retn

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Mike Gonta
look and see - many look but few see

http://mikegonta.com
Post 26 May 2017, 14:34
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Tomasz Grysztar
Assembly Artist


Joined: 16 Jun 2003
Posts: 6867
Location: Kraków, Poland
I'm OK with SetFilePointer, it just needed these corrections.
Post 26 May 2017, 14:51
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