osfmk/x86_64/bcopy.s

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License. The rights granted to you under the License
  10  * may not be used to create, or enable the creation or redistribution of,
  11  * unlawful or unlicensed copies of an Apple operating system, or to
  12  * circumvent, violate, or enable the circumvention or violation of, any
  13  * terms of an Apple operating system software license agreement.
  14  *
  15  * Please obtain a copy of the License at
  16  * http://www.opensource.apple.com/apsl/ and read it before using this file.
  17  *
  18  * The Original Code and all software distributed under the License are
  19  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  20  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  21  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  22  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  23  * Please see the License for the specific language governing rights and
  24  * limitations under the License.
  25  *
  26  * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
  27  */
  28 /*
  29  * @OSF_COPYRIGHT@
  30  */
  31 /*
  32  * Mach Operating System
  33  * Copyright (c) 1991,1990 Carnegie Mellon University
  34  * All Rights Reserved.
  35  *
  36  * Permission to use, copy, modify and distribute this software and its
  37  * documentation is hereby granted, provided that both the copyright
  38  * notice and this permission notice appear in all copies of the
  39  * software, derivative works or modified versions, and any portions
  40  * thereof, and that both notices appear in supporting documentation.
  41  *
  42  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
  43  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
  44  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
  45  *
  46  * Carnegie Mellon requests users of this software to return to
  47  *
  48  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
  49  *  School of Computer Science
  50  *  Carnegie Mellon University
  51  *  Pittsburgh PA 15213-3890
  52  *
  53  * any improvements or extensions that they make and grant Carnegie Mellon
  54  * the rights to redistribute these changes.
  55  */
  56 /*
  57  */
  58
  59 #include <i386/asm.h>
  60
  61 /* void *memcpy((void *) to, (const void *) from, (size_t) bcount) */
  62 /*                      rdi,                 rsi,             rdx   */
  63 /*
  64  * Note: memcpy does not support overlapping copies
  65  */
  66 ENTRY(memcpy)
  67         movq    %rdi, %rax                      /* return destination */
  68         movq    %rdx,%rcx
  69         cld                                     /* copy forwards */
  70         rep
  71         movsb
  72         ret
  73
  74 /* void bcopy((const char *) from, (char *) to, (unsigned int) count) */
  75 /*                            rdi,         rsi,                  rdx  */
  76
  77 ENTRY(bcopy_no_overwrite)
  78         xchgq   %rsi,%rdi
  79         jmp     EXT(memcpy)
  80
  81 /*
  82  * bcopy(src, dst, cnt)
  83  *       rdi, rsi, rdx
  84  *  ws@tools.de     (Wolfgang Solfrank, TooLs GmbH) +49-228-985800
  85  */
  86 ENTRY(bcopy)
  87         xchgq   %rsi,%rdi
  88         movq    %rdx,%rcx
  89
  90         movq    %rdi,%rax
  91         subq    %rsi,%rax
  92         cmpq    %rcx,%rax                       /* overlapping && src < dst? */
  93         jb      1f
  94
  95         cld                                     /* nope, copy forwards */
  96         rep
  97         movsb
  98         ret
  99
 100         /* ALIGN_TEXT */
 101 1:
 102         addq    %rcx,%rdi                       /* copy backwards */
 103         addq    %rcx,%rsi
 104         decq    %rdi
 105         decq    %rsi
 106         andq    $7,%rcx                         /* any fractional bytes? */
 107         std
 108         rep
 109         movsb
 110         movq    %rdx,%rcx                       /* copy remainder by 32-bit words */
 111         shrq    $3,%rcx
 112         subq    $7,%rsi
 113         subq    $7,%rdi
 114         rep
 115         movsq
 116         cld
 117         ret