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awilliam
GitHub Repository: awilliam/linux-vfio
 Path: blob/master/arch/mn10300/lib/memmove.S
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/* MN10300 Optimised simple memory to memory copy, with support for overlapping

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 * regions

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 *

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 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.

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 * Written by David Howells ([email protected])

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 *

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 * This program is free software; you can redistribute it and/or

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 * modify it under the terms of the GNU General Public Licence

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 * as published by the Free Software Foundation; either version

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 * 2 of the Licence, or (at your option) any later version.

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 */

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#include <asm/cache.h>

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        .section .text

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        .balign	L1_CACHE_BYTES

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###############################################################################

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#

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# void *memmove(void *dst, const void *src, size_t n)

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#

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###############################################################################

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	.globl	memmove

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        .type	memmove,@function

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memmove:

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	# fall back to memcpy if dst < src to work bottom up

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	cmp	d1,d0

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	bcs	memmove_memcpy

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	# work top down

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	movm	[d2,d3],(sp)

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	mov	d0,(12,sp)

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	mov	d1,(16,sp)

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	mov	(20,sp),d2			# count

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	add	d0,d2,a0			# dst end

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	add	d1,d2,a1			# src end

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	mov	d0,e3				# the return value

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	cmp	+0,d2

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	beq	memmove_done			# return if zero-length copy

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	# see if the three parameters are all four-byte aligned

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	or	d0,d1,d3

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	or	d2,d3

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	and	+3,d3

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	bne	memmove_1			# jump if not

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	# we want to transfer as much as we can in chunks of 32 bytes

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	add	-4,a1

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	cmp	+31,d2

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	bls	memmove_4_remainder		# 4-byte aligned remainder

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	add	-32,d2

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	mov	+32,d3

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memmove_4_loop:

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	mov	(a1),d0

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	sub_sub	+4,a1,+4,a0

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	mov	d0,(a0)

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	mov	(a1),d1

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	sub_sub	+4,a1,+4,a0

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	mov	d1,(a0)

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	mov	(a1),d0

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	sub_sub	+4,a1,+4,a0

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	mov	d0,(a0)

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	mov	(a1),d1

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	sub_sub	+4,a1,+4,a0

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	mov	d1,(a0)

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	mov	(a1),d0

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	sub_sub	+4,a1,+4,a0

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	mov	d0,(a0)

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	mov	(a1),d1

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	sub_sub	+4,a1,+4,a0

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	mov	d1,(a0)

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	mov	(a1),d0

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	sub_sub	+4,a1,+4,a0

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	mov	d0,(a0)

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	mov	(a1),d1

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	sub_sub	+4,a1,+4,a0

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	mov	d1,(a0)

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	sub	d3,d2

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	bcc	memmove_4_loop

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	add	d3,d2

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	beq	memmove_4_no_remainder

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memmove_4_remainder:

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	# cut 4-7 words down to 0-3

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	cmp	+16,d2

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	bcs	memmove_4_three_or_fewer_words

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	mov	(a1),d0

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	sub_sub	+4,a1,+4,a0

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	mov	d0,(a0)

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	mov	(a1),d1

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	sub_sub	+4,a1,+4,a0

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	mov	d1,(a0)

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	mov	(a1),e0

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	sub_sub	+4,a1,+4,a0

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	mov	e0,(a0)

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	mov	(a1),e1

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	sub_sub	+4,a1,+4,a0

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	mov	e1,(a0)

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	add	-16,d2

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	beq	memmove_4_no_remainder

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	# copy the remaining 1, 2 or 3 words

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memmove_4_three_or_fewer_words:

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	cmp	+8,d2

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	bcs	memmove_4_one_word

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	beq	memmove_4_two_words

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	mov	(a1),d0

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	sub_sub	+4,a1,+4,a0

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	mov	d0,(a0)

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memmove_4_two_words:

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	mov	(a1),d0

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	sub_sub	+4,a1,+4,a0

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	mov	d0,(a0)

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memmove_4_one_word:

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	mov	(a1),d0

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	sub_sub	+4,a1,+4,a0

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	mov	d0,(a0)

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memmove_4_no_remainder:

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	# check we copied the correct amount

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	# TODO: REMOVE CHECK

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	sub	e3,a0,d2

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	beq	memmove_done

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	break

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	break

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	break

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memmove_done:

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	mov	e3,a0

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	ret	[d2,d3],8

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	# handle misaligned copying

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memmove_1:

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	add	-1,a1

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	add	-1,d2

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	mov	+1,d3

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	setlb					# setlb requires the next insns

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						# to occupy exactly 4 bytes

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	sub	d3,d2

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	movbu	(a1),d0

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	sub_sub	d3,a1,d3,a0

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	movbu	d0,(a0)

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	lcc

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	mov	e3,a0

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	ret	[d2,d3],8

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memmove_memcpy:

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	jmp	memcpy

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memmove_end:

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	.size	memmove, memmove_end-memmove

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