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# _memmove() Author: Kees J. Bot 2 Jan 1994
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/*	_memmove()					Author: Kees J. Bot */
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/*								2 Jan 1994 */
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# void *_memmove(void *s1, const void *s2, size_t n)
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/* void *_memmove(void *s1, const void *s2, size_t n) */
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#       Copy a chunk of memory.  Handle overlap.
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/*	Copy a chunk of memory.  Handle overlap. */
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.intel_syntax
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/* */
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.globl __memmove, __memcpy
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.text
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#include "asm.h"
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           .align  16
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__memmove:
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ENTRY(_memmove)
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           push    ebp
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	push	%ebp
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           mov     ebp, esp
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	movl	%esp, %ebp
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           push    esi
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	push	%esi
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           push    edi
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	push	%edi
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           mov     edi, [ebp+8]     # String s1
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	movl	8(%ebp), %edi	/* String s1 */
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           mov     esi, [ebp+12]    # String s2
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	movl	12(%ebp), %esi	/* String s2 */
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           mov     ecx, [ebp+16]    # Length
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	movl	16(%ebp), %ecx	/* Length */
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           mov     eax, edi
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	movl	%edi, %eax
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           sub     eax, esi
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	subl	%esi, %eax
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           cmp     eax, ecx
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	cmpl	%ecx, %eax
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           jb      downwards        # if (s2 - s1) < n then copy downwards
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	jb	downwards	/* if (s2 - s1) < n then copy downwards */
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__memcpy:
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LABEL(_memcpy)
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           cld                      # Clear direction bit: upwards
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	cld	/* Clear direction bit: upwards */
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           cmp     ecx, 16
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	cmpl	$16, %ecx
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           jb      upbyte           # Don't bother being smart with short arrays
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	jb	upbyte	/* Don't bother being smart with short arrays */
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           mov     eax, esi
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	movl	%esi, %eax
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           or      eax, edi
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	orl	%edi, %eax
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           testb   al, 1
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	testb	$1, %al
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           jnz     upbyte           # Bit 0 set, use byte copy
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	jne	upbyte	/* Bit 0 set, use byte copy */
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           testb   al, 2
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	testb	$2, %al
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           jnz     upword           # Bit 1 set, use word copy
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	jne	upword	/* Bit 1 set, use word copy */
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uplword:
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uplword:
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           shrd    eax, ecx, 2      # Save low 2 bits of ecx in eax
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	shrdl	$2, %ecx, %eax	/* Save low 2 bits of ecx in eax */
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	shrl	$2, %ecx
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           shr     ecx, 2
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           rep movsd                # Copy longwords.
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	rep movsl	/* Copy longwords. */
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           shld    ecx, eax, 2      # Restore excess count
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	shldl	$2, %eax, %ecx	/* Restore excess count */
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upword:
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upword:
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	shrl	$1, %ecx
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           shr     ecx, 1
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           rep movsw                # Copy words
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	rep movsw	/* Copy words */
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           adc     ecx, ecx         # One more byte?
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	adcl	%ecx, %ecx	/* One more byte? */
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upbyte:
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upbyte:
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           rep movsb                # Copy bytes
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	rep movsb	/* Copy bytes */
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done:
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done:
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           mov     eax, [ebp+8]     # Absolutely noone cares about this value
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	movl	8(%ebp), %eax	/* Absolutely noone cares about this value */
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           pop     edi
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	pop	%edi
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           pop     esi
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	pop	%esi
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           pop     ebp
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	pop	%ebp
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           ret
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	ret
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# Handle bad overlap by copying downwards, don't bother to do word copies.
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/* Handle bad overlap by copying downwards, don't bother to do word copies. */
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downwards:
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downwards:
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           std                     # Set direction bit: downwards
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	std	/* Set direction bit: downwards */
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	leal	-1(%esi,%ecx,1), %esi
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           lea     esi, [esi+ecx-1]
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	leal	-1(%edi,%ecx,1), %edi
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           lea     edi, [edi+ecx-1]
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           rep movsb               # Copy bytes
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	rep movsb	/* Copy bytes */