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Author Topic: About LOCAL string  (Read 8257 times)
jj2007
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Re: About LOCAL string
« Reply #15 on: September 16, 2009, 08:49:25 PM »

For the lazy programmer - short and fast, works with all kind of LOCAL variables, including strings and structures:

Quote
MyTest proc
LOCAL MyVar1:DWORD, LocBuffer[120]:BYTE, MyVar2:DWORD
  call ClearLocals
  ret
MyTest endp

Code:
ClearLocals proc ; put "call ClearLocals" as first instruction after LOCALS - eax will be unchanged on exit
  push eax ; do not use with uses esi etc - push them manually behind the call!
  lea eax, [esp+8] ; pushed eax and ret address
  mov esp, ebp ; base page of calling procedure
  align 4 ; 74 instead of 123 cycles on Celeron M, no effect on P4
@@:
  push 0 ; 120 bytes: 196 cycles on P4
  cmp esp, eax ; rep stosd??
  ja @B
  sub esp, 8 ; 19 bytes with align 4
  pop eax
  ret
ClearLocals endp
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NightWare
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when dream comes true


Re: About LOCAL string
« Reply #16 on: September 16, 2009, 09:34:28 PM »

LOCAL szDir[124]:BYTE

how to initialize it to all 0? like this szBuffer db 124 dup(0)

when i define a LOCAL Var, what is the default value inside?

to init/re-init a string you just need to clean the first byte, here :
 mov BYTE PTR szDir,0
coz there is NO REASONS to clean the entire area (at least if your string functions are well coded...).
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ecube
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Re: About LOCAL string
« Reply #17 on: September 16, 2009, 10:25:49 PM »

You guys like the caps...I tend to use buffers for alot more than strings, and that's why I recommended the full clearing, is a piece of mind for me and doesn't limit. If he's sure he's just gonna mess with strings then YEAH, clearing the first byte is sufficient.
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