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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libc/] [machine/] [i386/] [strlen.S] - Blame information for rev 407

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Line No. Rev Author Line
1 148 jeremybenn 
/*
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 * ====================================================
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 * Copyright (C) 1998, 2002, 2008 by Red Hat Inc. All rights reserved.
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 *
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 * Permission to use, copy, modify, and distribute this
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 * software is freely granted, provided that this notice
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 * is preserved.
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 * ====================================================
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 */
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        #include "i386mach.h"
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        .global SYM (strlen)
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       SOTYPE_FUNCTION(strlen)
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SYM (strlen):
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        pushl ebp
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        movl esp,ebp
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        pushl edi
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        movl 8(ebp),edx
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#ifdef __OPTIMIZE_SIZE__
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        cld
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        movl edx,edi
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        movl $4294967295,ecx
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        xor eax,eax
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        repnz
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        scasb
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#else
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/* Modern x86 hardware is much faster at double-word
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   manipulation than with bytewise repnz scasb.  */
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/* Do byte-wise checks until string is aligned.  */
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        movl edx,edi
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        test $3,edi
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        je L5
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        movb (edi),cl
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        incl edi
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        testb cl,cl
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        je L15
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        test $3,edi
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        je L5
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        movb (edi),cl
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        incl edi
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        testb cl,cl
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        je L15
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        test $3,edi
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        je L5
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        movb (edi),cl
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        incl edi
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        testb cl,cl
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        je L15
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L5:
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        subl $4,edi
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/* loop performing 4 byte mask checking for desired 0 byte */
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        .p2align 4,,7
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L10:
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        addl $4,edi
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        movl (edi),ecx
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        leal -16843009(ecx),eax
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        notl ecx
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        andl ecx,eax
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        testl $-2139062144,eax
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        je L10
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/* Find which of four bytes is 0.  */
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        notl ecx
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        incl edi
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        testb cl,cl
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        je L15
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        incl edi
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        shrl $8,ecx
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        testb cl,cl
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        je L15
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        incl edi
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        shrl $8,ecx
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        testb cl,cl
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        je L15
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        incl edi
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#endif
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L15:
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        subl edx,edi
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        leal -1(edi),eax
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        leal -4(ebp),esp
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        popl edi
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        leave
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        ret

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