1 /*
   2  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
   3  * Use is subject to license terms.
   4  */
   5 
   6 /*
   7  * Copyright 2019 Joyent, Inc.
   8  */
   9 
  10 /*-
  11  * Copyright (c) 1993 The Regents of the University of California.
  12  * All rights reserved.
  13  *
  14  * Redistribution and use in source and binary forms, with or without
  15  * modification, are permitted provided that the following conditions
  16  * are met:
  17  * 1. Redistributions of source code must retain the above copyright
  18  *    notice, this list of conditions and the following disclaimer.
  19  * 2. Redistributions in binary form must reproduce the above copyright
  20  *    notice, this list of conditions and the following disclaimer in the
  21  *    documentation and/or other materials provided with the distribution.
  22  * 3. All advertising materials mentioning features or use of this software
  23  *    must display the following acknowledgement:
  24  *      This product includes software developed by the University of
  25  *      California, Berkeley and its contributors.
  26  * 4. Neither the name of the University nor the names of its contributors
  27  *    may be used to endorse or promote products derived from this software
  28  *    without specific prior written permission.
  29  *
  30  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  31  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  32  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  33  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  34  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  35  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  36  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  37  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  38  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  39  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  40  * SUCH DAMAGE.
  41  *
  42  * $FreeBSD: src/sys/amd64/amd64/support.S,v 1.102 2003/10/02 05:08:13 alc Exp $
  43  */
  44 
  45 #include <sys/asm_linkage.h>
  46 
  47 /*
  48  * Adapted from fbsd bcopy().
  49  *
  50  * bcopy(src, dst, cnt)
  51  *       rdi, rsi, rdx
  52  *  ws@tools.de     (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
  53  */
  54 
  55         ENTRY(ovbcopy)
  56         xchgq   %rsi,%rdi
  57         movq    %rdx,%rcx
  58 
  59         movq    %rdi,%rax
  60         subq    %rsi,%rax
  61         cmpq    %rcx,%rax               /* overlapping && src < dst? */
  62         jb      reverse
  63 
  64         shrq    $3,%rcx                 /* copy by 64-bit words */
  65         cld                             /* nope, copy forwards */
  66         rep
  67         movsq
  68         movq    %rdx,%rcx
  69         andq    $7,%rcx                 /* any bytes left? */
  70         rep
  71         movsb
  72         ret
  73 
  74 reverse:
  75         addq    %rcx,%rdi               /* copy backwards */
  76         addq    %rcx,%rsi
  77         decq    %rdi
  78         decq    %rsi
  79         andq    $7,%rcx                 /* any fractional bytes? */
  80         std
  81         rep
  82         movsb
  83         movq    %rdx,%rcx               /* copy remainder by 32-bit words */
  84         shrq    $3,%rcx
  85         subq    $7,%rsi
  86         subq    $7,%rdi
  87         rep
  88         movsq
  89         cld
  90         ret
  91         SET_SIZE(ovbcopy)
  92