xref: /illumos-gate/usr/src/lib/libc/i386/gen/memcpy.s (revision 46b59285)
1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License (the "License").
6 * You may not use this file except in compliance with the License.
7 *
8 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9 * or http://www.opensolaris.org/os/licensing.
10 * See the License for the specific language governing permissions
11 * and limitations under the License.
12 *
13 * When distributing Covered Code, include this CDDL HEADER in each
14 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15 * If applicable, add the following below this CDDL HEADER, with the
16 * fields enclosed by brackets "[]" replaced with your own identifying
17 * information: Portions Copyright [yyyy] [name of copyright owner]
18 *
19 * CDDL HEADER END
20 */
21
22/*
23 * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27	.file	"memcpy.s"
28
29#include <sys/asm_linkage.h>
30
31	ANSI_PRAGMA_WEAK(memmove,function)
32	ANSI_PRAGMA_WEAK(memcpy,function)
33
34#include "SYS.h"
35
36	ENTRY(memcpy)
37	movl	%edi,%edx	/ save register variables
38	pushl	%esi
39	movl	8(%esp),%edi	/ %edi = dest address
40	movl	12(%esp),%esi	/ %esi = source address
41	movl	16(%esp),%ecx	/ %ecx = length of string
42	movl	%edi,%eax	/ return value from the call
43
44	shrl	$2,%ecx		/ %ecx = number of words to move
45	rep ; smovl		/ move the words
46
47	movl	16(%esp),%ecx	/ %ecx = number of bytes to move
48	andl	$0x3,%ecx	/ %ecx = number of bytes left to move
49	rep ; smovb		/ move the bytes
50
51	popl	%esi		/ restore register variables
52	movl	%edx,%edi
53	ret
54	SET_SIZE(memcpy)
55
56
57	ENTRY(memmove)
58	pushl	%edi		/ save off %edi, %esi and move destination
59	movl	4+12(%esp),%ecx	/ get number of bytes to move
60	pushl	%esi
61	testl	%ecx,%ecx	/ if (n == 0)
62	je	.CleanupReturn	/    return(s);
63	movl	8+ 4(%esp),%edi	/ destination buffer address
64	movl	8+ 8(%esp),%esi	/ source buffer address
65.Common:
66	movl	$3,%eax		/ heavily used constant
67	cmpl	%esi,%edi	/ if (source addr > dest addr)
68	leal	-1(%esi,%ecx),%edx
69	jbe	.CopyRight	/
70	cmpl	%edx,%edi
71	jbe	.CopyLeft
72.CopyRight:
73	cmpl	$8,%ecx		/    if (size < 8 bytes)
74	jbe	.OneByteCopy	/        goto fast short copy loop
75.FourByteCopy:
76	movl	%ecx,%edx	/    save count
77	movl	%esi,%ecx	/    get source buffer 4 byte aligned
78	andl	%eax,%ecx
79	jz	.SkipAlignRight
80	subl	%ecx,%edx
81	rep;	smovb		/    do the byte part of copy
82.SkipAlignRight:
83	movl	%edx,%ecx
84	shrl	$2,%ecx
85	rep;	smovl		/    do the long word part
86	movl	%edx,%ecx	/    compute bytes left to move
87	andl	%eax,%ecx	/    complete copy of remaining bytes
88	jz	.CleanupReturn
89.OneByteCopy:
90	rep;	smovb		/    do the byte part of copy
91.CleanupReturn:
92	popl	%esi		/  }
93	popl	%edi		/  restore registers
94	movl	4(%esp),%eax	/  set up return value
95.Return:
96	ret			/  return(dba);
97
98.CopyLeft:
99	std				/ reverse direction bit (RtoL)
100	cmpl	$12,%ecx		/ if (size < 12)
101	ja	.BigCopyLeft		/ {
102	movl	%edx,%esi		/     src = src + size - 1
103	leal	-1(%ecx,%edi),%edi	/     dst = dst + size - 1
104	rep;	smovb			/    do the byte copy
105	cld				/    reset direction flag to LtoR
106	popl	%esi			/  }
107	popl	%edi			/  restore registers
108	movl	4(%esp),%eax		/  set up return value
109	ret				/  return(dba);
110.BigCopyLeft:				/ } else {
111	xchgl	%edx,%ecx
112	movl	%ecx,%esi		/ align source w/byte copy
113	leal	-1(%edx,%edi),%edi
114	andl	%eax,%ecx
115	jz	.SkipAlignLeft
116	addl	$1, %ecx		/ we need to insure that future
117	subl	%ecx,%edx		/ copy is done on aligned boundary
118	rep;	smovb
119.SkipAlignLeft:
120	movl	%edx,%ecx
121	subl	%eax,%esi
122	shrl	$2,%ecx			/ do 4 byte copy RtoL
123	subl	%eax,%edi
124	rep;	smovl
125	andl	%eax,%edx		/ do 1 byte copy whats left
126	jz	.CleanupReturnLeft
127	movl	%edx,%ecx
128	addl	%eax,%esi		/ rep; smovl instruction will decrement
129	addl	%eax,%edi		/ %edi, %esi by four after each copy
130					/ adding 3 will restore pointers to byte
131					/ before last double word copied
132					/ which is where they are expected to
133					/ be for the single byte copy code
134	rep;	smovb
135.CleanupReturnLeft:
136	cld				/ reset direction flag to LtoR
137	popl	%esi
138	popl	%edi			/ restore registers
139	movl	4(%esp),%eax		/ set up return value
140	ret				/ return(dba);
141	SET_SIZE(memmove)
142