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93 lines
2.3 KiB
PHP
93 lines
2.3 KiB
PHP
; string2dword - a useless string to double word conversion routine
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;
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; Copyright (c) 2003 Thomas Mathys
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; killer@vantage.ch
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;
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; This program is free software; you can redistribute it and/or modify
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; it under the terms of the GNU General Public License as published by
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; the Free Software Foundation; either version 2 of the License, or
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; (at your option) any later version.
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;
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; This program is distributed in the hope that it will be useful,
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; but WITHOUT ANY WARRANTY; without even the implied warranty of
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; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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; GNU General Public License for more details.
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;
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; You should have received a copy of the GNU General Public License
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; along with this program; if not, write to the Free Software
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; Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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;
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;********************************************************************
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; converts an asciiz string into an unsigned doubleword.
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; (base 10 is assumed)
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;
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; - first, leading whitespaces are skipped
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; - then the function converts the string, until it
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; finds the terminating zero, another character it
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; cannot convert or the number becomes too large.
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;
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; input : esi = pointer to string
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; output : eax = unsigned doubleword
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; the function tries to convert as
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; many digits as possible, before it
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; stops. if the value of the dword
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; becomes too large, 0xffffffff is
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; returned.
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; destroys : nothing
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;********************************************************************
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string2dword:
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push ebx
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push ecx
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push edx
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push esi
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pushfd
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xor ebx,ebx ; ebx : dword
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; skip leading whitespaces
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.skipspaces:
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lodsb
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cmp al,32 ; space
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je .skipspaces
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cmp al,12 ; ff
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je .skipspaces
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cmp al,10 ; lf
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je .skipspaces
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cmp al,13 ; cr
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je .skipspaces
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cmp al,9 ; ht
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je .skipspaces
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cmp al,11 ; vt
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je .skipspaces
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; convert string
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dec esi ; esi -> 1st non-whitespace
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.convert:
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xor eax,eax ; get character
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lodsb
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sub al,'0' ; convert to digit
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cmp al,9 ; is digit in range [0,9] ?
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ja .done ; nope -> stop conversion
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mov ecx,eax ; save new digit
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mov eax,10 ; dword = dword * 10
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mul ebx
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jc .overflow
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add eax,ecx ; + new digit
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jc .overflow
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mov ebx,eax
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jmp .convert
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.overflow:
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mov ebx,0xffffffff
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.done:
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mov eax,ebx
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popfd
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pop esi
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pop edx
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pop ecx
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pop ebx
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ret
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