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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  * memcpy.S
     30  *
     31  * Reasonably efficient memcpy, using aligned transfers at least
     32  * for the destination operand.
     33  */
     34 
     35 	.text
     36 	.globl	memcpy
     37 	.type	memcpy, @function
     38 memcpy:
     39 	movl	0xc(%esp),%ecx
     40 	movl	0x8(%esp),%edx
     41 	movl	0x4(%esp),%eax
     42 
     43 	jecxz	1f
     44 
     45 	pushl	%esi
     46 	pushl	%edi
     47 	pushl	%eax		/* Return value */
     48 
     49 	movl	%eax,%edi
     50 	movl	%edx,%esi
     51 
     52 	/* Initial alignment */
     53 	movl	%edi,%edx
     54 	shrl	$1,%edx
     55 	jnc	11f
     56 	movsb
     57 	decl	%ecx
     58 11:
     59 	movb	%cl,%al
     60 	cmpl	$2,%ecx
     61 	jb	13f
     62 
     63 	shrl	$1,%edx
     64 	jnc	12f
     65 	movsw
     66 	subl	$2,%ecx
     67 12:
     68 	/* Bulk transfer */
     69 	movb	%cl,%al
     70 	shrl	$2,%ecx
     71 	rep; movsl
     72 
     73 	/* Final alignment */
     74 	testb	$2,%al
     75 	jz	14f
     76 	movsw
     77 13:
     78 14:
     79 	testb	$1,%al
     80 	jz	15f
     81 	movsb
     82 15:
     83 
     84 	popl	%eax		/* Return value */
     85 	popl	%edi
     86 	popl	%esi
     87 1:
     88 	ret
     89 
     90 	.size	memcpy, .-memcpy
     91