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thecf



Joined: 23 Dec 2006
Posts: 23
thecf
esi = 'somefile.bin'

how can i remove the last four bytes from esi so it reads 'somefile'?
Post 05 Jan 2007, 18:01
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
Code:
proc strncpy dest, src, maxLength
  push    esi edi 

  mov     edi, [dest] 
  mov     esi, [src] 
  mov     ecx, [maxLength]
  test    ecx, ecx
  jz      .exit

.storeChar: 
  lodsb 
  stosb 
  test    al, al 
  jz      .exit 

.checkLength: 
  sub     ecx, 1 
  jnc     .storeChar 

  mov     byte [edi-1], 0

.exit: 
  pop     edi esi 
  ret 
endp    


That code is for strncpy, now if you just want to copy up to the file extention this could be a way:
Code:
proc removeExt buffer, fileName, bufferLength
  push    esi edi ebx

  mov     edi, [buffer]
  mov     esi, [fileName]
  mov     ecx, [bufferLength]
  mov     ebx, -1
  test    ecx, ecx
  jz      .return

.storeChar:
  lodsb
  stosb
  test    al, al
  jz      .exit
  cmp     al, '.'
  jne     .checkLength

  mov     ebx, esi

.checkLength:
  sub     ecx, 1
  jnc     .storeChar

  mov    byte [edi-1], 0
.exit:
  cmp    esi, ebx
  jb     .return

  mov    byte [ebx-1], 0

.return:
  pop     ebx edi esi
  ret
endp    


(Both codes untested, sorry, no time to check them)

[edit]I corrected the codes to ensure that the destination string will be null terminated (if the length is above 0)[/edit]
Post 05 Jan 2007, 19:01
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f0dder



Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
Code:
mov byte [esi+8], 0
    

Razz
Post 06 Jan 2007, 07:44
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rugxulo



Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)
rugxulo
Heh, f0dder, you read our minds. Laughing
Post 06 Jan 2007, 18:00
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f0dder



Joined: 19 Feb 2004
Posts: 3170
Location: Denmark
f0dder
...of course what the original poster probably wants is a routine to split a path into {path}{filename}{extension} components, but hey - Smile
Post 07 Jan 2007, 15:03
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LocoDelAssembly
Your code has a bug


Joined: 06 May 2005
Posts: 4633
Location: Argentina
LocoDelAssembly
The original poster keeps quiet so we still don't know if f0dder solution (which I was very tempted to post too Razz) or my solution fits his needs.
Post 07 Jan 2007, 15:12
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