source: bootcd/isolinux/syslinux-6.03/com32/lib/memmove.S

Last change on this file was e16e8f2, checked in by Edwin Eefting <edwin@datux.nl>, 3 years ago

bootstuff
  • Property mode set to 100644
File size: 2.8 KB
Line 
1/* ----------------------------------------------------------------------- *
2 *
3 *   Copyright 2008 H. Peter Anvin - All Rights Reserved
4 *   Copyright 2010 Intel Corporation; author: H. Peter Anvin
5 *
6 *   Permission is hereby granted, free of charge, to any person
7 *   obtaining a copy of this software and associated documentation
8 *   files (the "Software"), to deal in the Software without
9 *   restriction, including without limitation the rights to use,
10 *   copy, modify, merge, publish, distribute, sublicense, and/or
11 *   sell copies of the Software, and to permit persons to whom
12 *   the Software is furnished to do so, subject to the following
13 *   conditions:
14 *
15 *   The above copyright notice and this permission notice shall
16 *   be included in all copies or substantial portions of the Software.
17 *
18 *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
19 *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
20 *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
21 *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
22 *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
23 *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
24 *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
25 *   OTHER DEALINGS IN THE SOFTWARE.
26 *
27 * ----------------------------------------------------------------------- */
28
29/*
30 * memmove.S
31 *
32 * Reasonably efficient memmove, using aligned transfers at least
33 * for the destination operand.
34 */
35
36        .globl  memmove
37        .type   memmove,@function
38        .text
39memmove:
40        movl    0xc(%esp),%ecx
41        movl    0x8(%esp),%edx
42        movl    0x4(%esp),%eax
43
44        jecxz   4f
45
46        pushl   %esi
47        pushl   %edi
48        pushl   %eax            /* Return value */
49
50        movl    %eax,%edi
51        movl    %edx,%esi
52
53        cmpl    %edi,%esi
54        jb      2f
55
56        /* source >= dest, forwards move */
57
58        /* Initial alignment */
591:
60        movl    %edi,%edx
61        shrl    $1,%edx
62        jnc     11f
63        movsb
64        decl    %ecx
6511:
66        movb    %cl,%al
67        cmpl    $2,%ecx
68        jb      13f
69
70        shrl    $1,%edx
71        jnc     12f
72        movsw
73        subl    $2,%ecx
7412:
75        /* Bulk transfer */
76        movb    %cl,%al
77        shrl    $2,%ecx
78        rep; movsl
79
80        /* Final alignment */
81        testb   $2,%al
82        jz      14f
83        movsw
8413:
8514:
86        testb   $1,%al
87        jz      15f
88        movsb
8915:
90        /* Common exit stub */
913:
92        popl    %eax            /* Return value */
93        popl    %edi
94        popl    %esi
954:
96        ret
97
98
992:
100        /* source < dest, backwards move if overlap */
101        leal    -1(%ecx,%esi),%eax
102        cmpl    %eax,%edi
103        ja      1b                      /* No overlap, after all... */
104
105        std
106        leal    -1(%ecx,%edi),%edi
107        movl    %eax,%esi
108
109        /* Initial alignment */
110        movl    %edi,%edx
111        shrl    $1,%edx
112        jc      21f
113        movsb
114        decl    %ecx
11521:
116        decl    %esi
117        decl    %edi
118        movb    %cl,%al
119        cmpl    $2,%ecx
120        jb      23f
121        shrl    $1,%edx
122        jc      22f
123        movsw
124        subl    $2,%ecx
12522:
126        /* Bulk transfer */
127        subl    $2,%esi
128        subl    $2,%edi
129        movb    %cl,%al
130        shrl    $2,%ecx
131        rep; movsl
132
133        /* Final alignment */
134        addl    $2,%esi
135        addl    $2,%edi
136        testb   $2,%al
137        jz      24f
138        movsw
13923:
14024:
141        incl    %esi
142        incl    %edi
143        testb   $1,%al
144        jz      25f
145        movsb
14625:
147        cld
148        jmp     3b
149
150        .size   memmove, .-memmove
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