GetFileExtension - Get the Extension of a filename, it reads the extension of a filename including the dot separator, only condition to use the procedure is to avoid NULL pointers.

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Vortex

Extremely Active Member

Group: Moderators
Posts: 140
Member No.: 8
Joined: 13-May 04

Here is a GetFileExtension procedure. It reads the extension of a filename including the dot separator. The only condition to use the procedure is to avoid NULL pointers.

CODE

.386
.model flat,stdcall
option casemap:none

.data

GFEtable db 1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
db 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0
.code

GetFileExtension PROC uses esi _file:DWORD

mov esi,_file
mov edx,OFFSET GFEtable
xor ecx,ecx
l0:
mov eax,esi ; The procedure returns the address of the filename
@@: ; if there is no extension
add esi,1
mov cl,BYTE PTR [esi]
cmp BYTE PTR [edx+ecx],0
je @b
cmp cl,'.'
je l0
ret

GetFileExtension ENDP

END

Attached File ( Number of downloads: 39 )


SeaFarer
Extremely Active Member Group: Members Posts: 1753 Member No.: 1464 Joined: 2-September 05	At 597 bytes, what a gem! Great example! Hutch's site is right... Caution! Hi-speed software! Thanks for sharing.


Vortex
Extremely Active Member Group: Moderators Posts: 140 Member No.: 8 Joined: 13-May 04	SeaFarer, Probably, the algo is oversized but the lookup table there is intended to speed up the search engine. Maybe, it could be possibe to recode the procedure with MMX instructions to get a shorter version.


Slider
Extremely Active Member Group: Moderators Posts: 287 Member No.: 5004 Joined: 11-May 07	Thanks Vortex. What are some ways that it could be used for ?


Vortex
Extremely Active Member Group: Moderators Posts: 140 Member No.: 8 Joined: 13-May 04	Hi Slider, There are some cases where you would like to extract the extensions from full qualified paths. A typical example is determining if the user is typing a file name with the correct extension.

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