1 /*
   2  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5 
   6 #pragma ident   "%Z%%M% %I%     %E% SMI"
   7 
   8 /*-
   9  * Copyright (c) 1993 The Regents of the University of California.
  10  * All rights reserved.
  11  *
  12  * Redistribution and use in source and binary forms, with or without
  13  * modification, are permitted provided that the following conditions
  14  * are met:
  15  * 1. Redistributions of source code must retain the above copyright
  16  *    notice, this list of conditions and the following disclaimer.
  17  * 2. Redistributions in binary form must reproduce the above copyright
  18  *    notice, this list of conditions and the following disclaimer in the
  19  *    documentation and/or other materials provided with the distribution.
  20  * 3. All advertising materials mentioning features or use of this software
  21  *    must display the following acknowledgement:
  22  *      This product includes software developed by the University of
  23  *      California, Berkeley and its contributors.
  24  * 4. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  *
  40  * $FreeBSD: src/sys/amd64/amd64/support.S,v 1.102 2003/10/02 05:08:13 alc Exp $
  41  */
  42 
  43 #include <sys/asm_linkage.h>
  44 
  45 #if defined(__lint)
  46 
  47 /*
  48  * Overlapping bcopy (source and target may overlap arbitrarily).
  49  */
  50 /* ARGSUSED */
  51 void
  52 ovbcopy(const void *from, void *to, size_t count)
  53 {}
  54 
  55 #else   /* __lint */
  56 
  57 /*
  58  * Adapted from fbsd bcopy().
  59  *
  60  * bcopy(src, dst, cnt)
  61  *       rdi, rsi, rdx
  62  *  ws@tools.de     (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
  63  */
  64 
  65 #if defined(__amd64)
  66 
  67         ENTRY(ovbcopy)
  68         xchgq   %rsi,%rdi
  69         movq    %rdx,%rcx
  70 
  71         movq    %rdi,%rax
  72         subq    %rsi,%rax
  73         cmpq    %rcx,%rax               /* overlapping && src < dst? */
  74         jb      reverse
  75 
  76         shrq    $3,%rcx                 /* copy by 64-bit words */
  77         cld                             /* nope, copy forwards */
  78         rep
  79         movsq
  80         movq    %rdx,%rcx
  81         andq    $7,%rcx                 /* any bytes left? */
  82         rep
  83         movsb
  84         ret
  85 
  86 reverse:
  87         addq    %rcx,%rdi               /* copy backwards */
  88         addq    %rcx,%rsi
  89         decq    %rdi
  90         decq    %rsi
  91         andq    $7,%rcx                 /* any fractional bytes? */
  92         std
  93         rep
  94         movsb
  95         movq    %rdx,%rcx               /* copy remainder by 32-bit words */
  96         shrq    $3,%rcx
  97         subq    $7,%rsi
  98         subq    $7,%rdi
  99         rep
 100         movsq
 101         cld
 102         ret
 103         SET_SIZE(ovbcopy)
 104 
 105 #elif defined(__i386)
 106 
 107         ENTRY(ovbcopy)
 108         pushl   %esi
 109         pushl   %edi
 110         movl    12(%esp),%esi
 111         movl    16(%esp),%edi
 112         movl    20(%esp),%ecx
 113 
 114         movl    %edi,%eax
 115         subl    %esi,%eax
 116         cmpl    %ecx,%eax               /* overlapping && src < dst? */
 117         jb      reverse
 118 
 119         shrl    $2,%ecx                 /* copy by 32-bit words */
 120         cld                             /* nope, copy forwards */
 121         rep
 122         movsl
 123         movl    20(%esp),%ecx
 124         andl    $3,%ecx                 /* any bytes left? */
 125         rep
 126         movsb
 127         popl    %edi
 128         popl    %esi
 129         ret
 130 
 131 reverse:
 132         addl    %ecx,%edi               /* copy backwards */
 133         addl    %ecx,%esi
 134         decl    %edi
 135         decl    %esi
 136         andl    $3,%ecx                 /* any fractional bytes? */
 137         std
 138         rep
 139         movsb
 140         movl    20(%esp),%ecx           /* copy remainder by 32-bit words */
 141         shrl    $2,%ecx
 142         subl    $3,%esi
 143         subl    $3,%edi
 144         rep
 145         movsl
 146         popl    %edi
 147         popl    %esi
 148         cld
 149         ret
 150         SET_SIZE(ovbcopy)
 151 
 152 #endif  /* __i386 */
 153 
 154 #endif  /* __lint */