1/*        $NetBSD: memcpy.S,v 1.3 2011/01/25 04:45:28 matt Exp $      */
2/*-
3 * Copyright (c) 1990, 1993
4 *        The Regents of the University of California.  All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 * 3. Neither the name of the University nor the names of its contributors
15 *    may be used to endorse or promote products derived from this software
16 *    without specific prior written permission.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31#include <machine/asm.h>
32
33/* .asciz "@(#)memcpy.s       8.1 (Berkeley) 6/4/93" */
34RCSID("$NetBSD: memcpy.S,v 1.3 2011/01/25 04:45:28 matt Exp $")
35
36/*
37 * void *memcpy(dst, src, size)
38 * returns dst
39 *
40 * This optimises the usual case (count < 65536) at the expense
41 * of some extra memory references and branches when count >= 65536.
42 */
43
44ENTRY(memcpy, 0)
45          movzwl    $65535,%r0          /* %r0 = 64K (needed below) */
46          movq      8(%ap),%r1          /* %r1 = src, %r2 = length */
47          movl      4(%ap),%r3          /* %r3 = dst */
48          cmpl      %r1,%r3
49          bgtru     1f                  /* normal forward case */
50          beql      2f                  /* equal, nothing to do */
51          addl2     %r2,%r1             /* overlaps iff src<dst but src+len>dst */
52          cmpl      %r1,%r3
53          bgtru     4f                  /* overlapping, must move backwards */
54          subl2     %r2,%r1
55
561:        /* move forward */
57          cmpl      %r2,%r0
58          bgtru     3f                  /* stupid movc3 limitation */
59          movc3     %r2,(%r1),(%r3)     /* move it all */
602:
61          movl      4(%ap),%r0          /* return original dst */
62          ret
633:
64          subl2     %r0,12(%ap)         /* adjust length by 64K */
65          movc3     %r0,(%r1),(%r3)     /* move 64K */
66          movl      12(%ap),%r2
67          decw      %r0                 /* from 0 to 65535 */
68          brb       1b                  /* retry */
69
704:        /* move backward */
71          addl2     %r2,%r3
725:
73          cmpl      %r2,%r0
74          bgtru     6f                  /* stupid movc3 limitation */
75          subl2     %r2,%r1
76          subl2     %r2,%r3
77          movc3     %r2,(%r1),(%r3)     /* move it all */
78          movl      4(%ap),%r0          /* return original dst */
79          ret
806:
81          subl2     %r0,12(%ap)         /* adjust length by 64K */
82          subl2     %r0,%r1
83          subl2     %r0,%r3
84          movc3     %r0,(%r1),(%r3)     /* move 64K */
85          movl      12(%ap),%r2
86          decw      %r0
87          subl2     %r0,%r1
88          subl2     %r0,%r3
89          brb       5b
90END(memcpy)
91