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      1 /* ----------------------------------------------------------------------- *
      2  *
      3  *   Copyright 2008 H. Peter Anvin - All Rights Reserved
      4  *
      5  *   Permission is hereby granted, free of charge, to any person
      6  *   obtaining a copy of this software and associated documentation
      7  *   files (the "Software"), to deal in the Software without
      8  *   restriction, including without limitation the rights to use,
      9  *   copy, modify, merge, publish, distribute, sublicense, and/or
     10  *   sell copies of the Software, and to permit persons to whom
     11  *   the Software is furnished to do so, subject to the following
     12  *   conditions:
     13  *
     14  *   The above copyright notice and this permission notice shall
     15  *   be included in all copies or substantial portions of the Software.
     16  *
     17  *   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
     18  *   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
     19  *   OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
     20  *   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
     21  *   HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
     22  *   WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     23  *   FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
     24  *   OTHER DEALINGS IN THE SOFTWARE.
     25  *
     26  * ----------------------------------------------------------------------- */
     27 
     28 /*
     29  * memmove.S
     30  *
     31  * Reasonably efficient memmove, using aligned transfers at least
     32  * for the destination operand.
     33  */
     34 
     35 	.globl	memmove
     36 	.type	memmove,@function
     37 	.text
     38 memmove:
     39 	jecxz	3f
     40 
     41 	pushl	%esi
     42 	pushl	%edi
     43 	pushl	%eax		/* Return value */
     44 
     45 	movl	%eax,%edi
     46 	movl	%edx,%esi
     47 
     48 	cmpl	%edi,%esi
     49 	jb	1f
     50 
     51 	/* source >= dest, forwards move */
     52 
     53 	/* Initial alignment */
     54 	movl	%edi,%edx
     55 	shrl	$1,%edx
     56 	jnc	11f
     57 	movsb
     58 	decl	%ecx
     59 11:
     60 	movb	%cl,%al
     61 	cmpl	$2,%ecx
     62 	jb	13f
     63 
     64 	shrl	$1,%edx
     65 	jnc	12f
     66 	movsw
     67 	subl	$2,%ecx
     68 12:
     69 	/* Bulk transfer */
     70 	movb	%cl,%al
     71 	shrl	$2,%ecx
     72 	rep; movsl
     73 
     74 	/* Final alignment */
     75 	testb	$2,%al
     76 	jz	14f
     77 	movsw
     78 13:
     79 14:
     80 	testb	$1,%al
     81 	jz	15f
     82 	movsb
     83 15:
     84 	jmp	2f
     85 
     86 
     87 1:
     88 	/* source < dest, backwards move */
     89 	std
     90 	leal	-1(%ecx,%esi),%esi
     91 	leal	-1(%ecx,%edi),%edi
     92 
     93 	/* Initial alignment */
     94 	movl	%edi,%edx
     95 	shrl	$1,%edx
     96 	jc	21f
     97 	movsb
     98 	decl	%ecx
     99 21:
    100 	decl	%esi
    101 	decl	%edi
    102 	movb	%cl,%al
    103 	cmpl	$2,%ecx
    104 	jb	23f
    105 	shrl	$1,%edx
    106 	jc	22f
    107 	movsw
    108 	subl	$2,%ecx
    109 22:
    110 	/* Bulk transfer */
    111 	subl	$2,%esi
    112 	subl	$2,%edi
    113 	movb	%cl,%al
    114 	shrl	$2,%ecx
    115 	rep; movsl
    116 
    117 	/* Final alignment */
    118 	addl	$2,%esi
    119 	addl	$2,%edi
    120 	testb	$2,%al
    121 	jz	24f
    122 	movsw
    123 23:
    124 24:
    125 	incl	%esi
    126 	incl	%edi
    127 	testb	$1,%al
    128 	jz	25f
    129 	movsb
    130 25:
    131 	cld
    132 2:
    133 	popl	%eax		/* Return value */
    134 	popl	%edi
    135 	popl	%esi
    136 3:
    137 	ret
    138 
    139 	.size	memmove, .-memmove
    140