e09d2f42db
This saves three cycles per character, and reduces the size of the function by eight bytes (the loop is unrolled eight times). Thanks to davidg for pointing this out.
126 lines
3.2 KiB
ArmAsm
126 lines
3.2 KiB
ArmAsm
/*
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* Copyright (c) 1993 Winning Strategies, Inc.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by Winning Strategies, Inc.
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* 4. The name of the author may not be used to endorse or promote products
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* derived from this software withough specific prior written permission
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
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* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* $Id: strcmp.s,v 1.2 1993/10/08 01:25:51 jtc Exp $
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*/
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#if defined(LIBC_RCS) && !defined(lint)
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.text
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.asciz "$Id: strcmp.s,v 1.2 1993/10/08 01:25:51 jtc Exp $"
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#endif /* LIBC_RCS and not lint */
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#include "DEFS.h"
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/*
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* strcmp(s1, s2)
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* return an integer greater than, equal to, or less than 0,
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* according as string s1 is greater than, equal to, or less
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* than the string s2.
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*
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* %eax - pointer to s1
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* %edx - pointer to s2
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*
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* Written by:
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* J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
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*/
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/*
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* I've unrolled the loop eight times: large enough to make a
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* significant difference, and small enough not to totally trash the
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* cashe.
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*/
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ENTRY(strcmp)
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movl 0x04(%esp),%eax
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movl 0x08(%esp),%edx
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jmp L2 /* Jump into the loop! */
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.align 2,0x90
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L1: incl %eax
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incl %edx
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L2: movb (%eax),%cl
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testb %cl,%cl /* null terminator??? */
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je L3
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cmpb %cl,(%edx) /* chars match??? */
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jne L3
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incl %eax
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incl %edx
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movb (%eax),%cl
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testb %cl,%cl
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je L3
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cmpb %cl,(%edx)
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jne L3
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incl %eax
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incl %edx
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movb (%eax),%cl
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testb %cl,%cl
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je L3
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cmpb %cl,(%edx)
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jne L3
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incl %eax
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incl %edx
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movb (%eax),%cl
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testb %cl,%cl
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je L3
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cmpb %cl,(%edx)
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jne L3
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incl %eax
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incl %edx
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movb (%eax),%cl
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testb %cl,%cl
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je L3
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cmpb %cl,(%edx)
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jne L3
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incl %eax
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incl %edx
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movb (%eax),%cl
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testb %cl,%cl
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je L3
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cmpb %cl,(%edx)
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jne L3
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incl %eax
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incl %edx
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movb (%eax),%cl
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testb %cl,%cl
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je L3
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cmpb %cl,(%edx)
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jne L3
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incl %eax
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incl %edx
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movb (%eax),%cl
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testb %cl,%cl
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je L3
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cmpb %cl,(%edx)
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je L1
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.align 2, 0x90
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L3: movsbl (%eax),%eax /* unsigned comparison */
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movsbl (%edx),%edx
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subl %edx,%eax
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ret
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