/* MN10300 Optimised simple memory to memory copy, with support for overlapping
* regions
*
* Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
* Written by David Howells (dhowells@redhat.com)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public Licence
* as published by the Free Software Foundation; either version
* 2 of the Licence, or (at your option) any later version.
*/
#include <asm/cache.h>
.section .text
.balign L1_CACHE_BYTES
###############################################################################
#
# void *memmove(void *dst, const void *src, size_t n)
#
###############################################################################
.globl memmove
.type memmove,@function
memmove:
# fall back to memcpy if dst < src to work bottom up
cmp d1,d0
bcs memmove_memcpy
# work top down
movm [d2,d3],(sp)
mov d0,(12,sp)
mov d1,(16,sp)
mov (20,sp),d2 # count
add d0,d2,a0 # dst end
add d1,d2,a1 # src end
mov d0,e3 # the return value
cmp +0,d2
beq memmove_done # return if zero-length copy
# see if the three parameters are all four-byte aligned
or d0,d1,d3
or d2,d3
and +3,d3
bne memmove_1 # jump if not
# we want to transfer as much as we can in chunks of 32 bytes
add -4,a1
cmp +31,d2
bls memmove_4_remainder # 4-byte aligned remainder
add -32,d2
mov +32,d3
memmove_4_loop:
mov (a1),d0
sub_sub +4,a1,+4,a0
mov d0,(a0)
mov (a1),d1
sub_sub +4,a1,+4,a0
mov d1,(a0)
mov (a1),d0
sub_sub +4,a1,+4,a0
mov d0,(a0)
mov (a1),d1
sub_sub +4,a1,+4,a0
mov d1,(a0)
mov (a1),d0
sub_sub +4,a1,+4,a0
mov d0,(a0)
mov (a1),d1
sub_sub +4,a1,+4,a0
mov d1,(a0)
mov (a1),d0
sub_sub +4,a1,+4,a0
mov d0,(a0)
mov (a1),d1
sub_sub +4,a1,+4,a0
mov d1,(a0)
sub d3,d2
bcc memmove_4_loop
add d3,d2
beq memmove_4_no_remainder
memmove_4_remainder:
# cut 4-7 words down to 0-3
cmp +16,d2
bcs memmove_4_three_or_fewer_words
mov (a1),d0
sub_sub +4,a1,+4,a0
mov d0,(a0)
mov (a1),d1
sub_sub +4,a1,+4,a0
mov d1,(a0)
mov (a1),e0
sub_sub +4,a1,+4,a0
mov e0,(a0)
mov (a1),e1
sub_sub +4,a1,+4,a0
mov e1,(a0)
add -16,d2
beq memmove_4_no_remainder
# copy the remaining 1, 2 or 3 words
memmove_4_three_or_fewer_words:
cmp +8,d2
bcs memmove_4_one_word
beq memmove_4_two_words
mov (a1),d0
sub_sub +4,a1,+4,a0
mov d0,(a0)
memmove_4_two_words:
mov (a1),d0
sub_sub +4,a1,+4,a0
mov d0,(a0)
memmove_4_one_word:
mov (a1),d0
sub_sub +4,a1,+4,a0
mov d0,(a0)
memmove_4_no_remainder:
# check we copied the correct amount
# TODO: REMOVE CHECK
sub e3,a0,d2
beq memmove_done
break
break
break
memmove_done:
mov e3,a0
ret [d2,d3],8
# handle misaligned copying
memmove_1:
add -1,a1
add -1,d2
mov +1,d3
setlb # setlb requires the next insns
# to occupy exactly 4 bytes
sub d3,d2
movbu (a1),d0
sub_sub d3,a1,d3,a0
movbu d0,(a0)
lcc
mov e3,a0
ret [d2,d3],8
memmove_memcpy:
jmp memcpy
memmove_end:
.size memmove, memmove_end-memmove
