214 lines
9.2 KiB
NASM
214 lines
9.2 KiB
NASM
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;*****************************************************************************
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;*
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;* Open Watcom Project
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;*
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;* Portions Copyright (c) 1983-2002 Sybase, Inc. All Rights Reserved.
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;*
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;* ========================================================================
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;*
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;* This file contains Original Code and/or Modifications of Original
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;* Code as defined in and that are subject to the Sybase Open Watcom
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;* Public License version 1.0 (the 'License'). You may not use this file
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;* except in compliance with the License. BY USING THIS FILE YOU AGREE TO
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;* ALL TERMS AND CONDITIONS OF THE LICENSE. A copy of the License is
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;* provided with the Original Code and Modifications, and is also
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;* available at www.sybase.com/developer/opensource.
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;*
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;* The Original Code and all software distributed under the License are
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;* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
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;* EXPRESS OR IMPLIED, AND SYBASE AND ALL CONTRIBUTORS HEREBY DISCLAIM
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;* ALL SUCH WARRANTIES, INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF
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;* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR
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;* NON-INFRINGEMENT. Please see the License for the specific language
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;* governing rights and limitations under the License.
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;*
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;* ========================================================================
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;*
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;* Description: Intel 386 implementation strcmp().
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;*
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;*****************************************************************************
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include mdef.inc
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include struct.inc
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ifdef _PROFILE
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include p5prof.inc
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endif
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modstart _strcmp,para
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cmp4 macro off
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mov ebx,off[eax] ; get dword from op1
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mov ecx,off[edx] ; get dword from op2
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cmp ecx,ebx ; compare them
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jne unequal ; quit if not equal
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ife off-12
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add eax,off+4 ; point to next group of dwords
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add edx,off+4 ; ...
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endif
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not ecx ; ...
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add ebx,0FEFEFEFFh ; determine if '\0' is one of bytes
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and ebx,ecx ; ...
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and ebx,80808080h ; ebx will be non-zero if '\0' found
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endm
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defpe strcmp
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xdefp "C",strcmp
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ifdef _PROFILE
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P5Prolog
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endif
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ifdef __STACK__
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mov eax,4[esp] ; get p1
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mov edx,8[esp] ; get p2
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endif
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cmp eax,edx ; pointers equal ?
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je equalnorst ; yes, return 0
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ifndef __STACK__
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push ecx ; save register
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endif
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test al,3 ; p1 aligned ?
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jne realign ; no, go and realign
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test dl,3 ; p2 aligned ?
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jne slowcpy ; no, do the slow copy (impossible to align both)
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fastcpy:
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push ebx ; save register
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align 4
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_loop ; - loop
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cmp4 0 ; - - compare first dword
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_quif ne ; - - quit if end of string
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cmp4 4 ; - - compare second dword
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_quif ne ; - - quit if end of string
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cmp4 8 ; - - compare third dword
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_quif ne ; - - quit if end of string
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cmp4 12 ; - - compare fourth dword
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_until ne ; - until end of string
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equalrst: ; strings equal, restore registers
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pop ebx ; restore register
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ifndef __STACK__
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pop ecx ; ...
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endif
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equalnorst: ; strings equal, skip register restore
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sub eax,eax ; indicate strings equal
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ifdef _PROFILE
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P5Epilog
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endif
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ret ; return
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unequal: ; dword was not equal
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_guess ; guess strings are equal
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cmp bl,cl ; - check low bytes
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_quif ne ; - quit if not equal
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cmp bl,0 ; - stop if end of string
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je equalrst ; - ...
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cmp bh,ch ; - check next bytes
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_quif ne ; - quit if not equal
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cmp bh,0 ; - stop if end of string
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je equalrst ; - ...
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shr ebx,16 ; - shift top 2 bytes to bottom
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shr ecx,16 ; - ...
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cmp bl,cl ; - check third byte
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_quif ne ; - quit if not equal
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cmp bl,0 ; - stop if end of string
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je equalrst ; - ...
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cmp bh,ch ; - check high order byte
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;; we know at this point that bh != ch, just have to do the compare
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;; _quif ne ; - quit if not equal
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;; cmp bh,0 ; - stop if end of string
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;; je equalrst ; - ...
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_endguess ; endguess
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sbb eax,eax ; eax = 0 if op1>op2, -1 if op1<op2
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or al,1 ; eax = 1 if op1>op2, -1 if op1<op2
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pop ebx ; restore registers
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ifndef __STACK__
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pop ecx ; ...
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endif
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ifdef _PROFILE
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P5Epilog
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endif
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ret ; return
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align 4
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realign:
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_loop ; - loop
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mov cl,[eax] ; get byte from p1
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inc eax ; point to next byte
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mov ch,[edx] ; get byte from p2
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inc edx ; point to next byte
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cmp cl,ch ; bytes equal?
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jne unequal2 ; unequal, quit
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or cl,cl ; end of string ?
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je equal2 ; yes, quit
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test al,3 ; check alignment
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_until e ; until aligned
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test dl,3 ; p2 aligned ?
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je fastcpy ; yes
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align 4
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slowcpy:
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_loop
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mov ecx,[eax] ; get aligned 4 bytes
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cmp cl,[edx] ; check 1st byte
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jne unequal2 ; bytes not equal
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or cl,cl ; end of string?
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je equal2 ; yes, quit
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cmp ch,[edx+1] ; check 2nd byte
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jne unequal2 ; bytes not equal
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or ch,ch ; end of string?
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je equal2 ; yes, quit
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shr ecx,16 ; move next pair of bytes to be tested
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cmp cl,[edx+2] ; check 3rd byte
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jne unequal2 ; bytes not equal
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or cl,cl ; end of string?
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je equal2 ; yes, quit
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cmp ch,[edx+3] ; check 4th byte
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jne unequal2 ; bytes not equal
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or ch,ch ; end of string?
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je equal2 ; yes, quit
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mov ecx,[eax+4] ; get next aligned 4 bytes
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cmp cl,[edx+4] ; check 5th byte
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jne unequal2 ; bytes not equal
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or cl,cl ; end of string?
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je equal2 ; yes, quit
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cmp ch,[edx+5] ; check 6th byte
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jne unequal2 ; bytes not equal
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or ch,ch ; end of string?
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je equal2 ; yes, quit
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shr ecx,16 ; move next pair of bytes to be tested
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cmp cl,[edx+6] ; check 7th byte
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jne unequal2 ; bytes not equal
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or cl,cl ; end of string?
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je equal2 ; yes, quit
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cmp ch,[edx+7] ; check 8th byte
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jne unequal2 ; bytes not equal
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add eax,8 ; next 8 bytes
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add edx,8 ; next 8 bytes
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or ch,ch ; end of string?
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_until e ; until equal
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equal2:
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xor eax,eax ; return 0
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ifndef __STACK__
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pop ecx ; restore registers
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endif
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ifdef _PROFILE
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P5Epilog
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endif
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ret ; return
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unequal2:
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sbb eax,eax ; eax = 0 if op1>op2, -1 if op1<op2
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or al,1 ; eax = 1 if op1>op2, -1 if op1<op2
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ifndef __STACK__
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pop ecx ; restore registers
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endif
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ifdef _PROFILE
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P5Epilog
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endif
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ret ; return
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endproc strcmp
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endmod
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end
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