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arch/mn10300/lib/memset.S
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/* Optimised simple memory fill
*
* 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 *memset(void *dst, int c, size_t n)
#
###############################################################################
.globl memset
.type memset,@function
memset:
movm [d2,d3],(sp)
mov d0,(12,sp)
mov d1,(16,sp)
mov (20,sp),d2 # count
mov d0,a0 # dst
mov d0,e3 # the return value
cmp +0,d2
beq memset_done # return if zero-length fill
# see if the region parameters are four-byte aligned
or d0,d2,d3
and +3,d3
bne memset_1 # jump if not
extbu d1
mov_asl d1,d3,8,d1
or_asl d1,d3,8,d1
or_asl d1,d3,8,d1
or d3,d1
# we want to transfer as much as we can in chunks of 32 bytes
cmp +31,d2
bls memset_4_remainder # 4-byte aligned remainder
add -32,d2
mov +32,d3
memset_4_loop:
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
sub d3,d2
bcc memset_4_loop
add d3,d2
beq memset_4_no_remainder
memset_4_remainder:
# cut 4-7 words down to 0-3
cmp +16,d2
bcs memset_4_three_or_fewer_words
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
mov d1,(a0+)
add -16,d2
beq memset_4_no_remainder
# copy the remaining 1, 2 or 3 words
memset_4_three_or_fewer_words:
cmp +8,d2
bcs memset_4_one_word
beq memset_4_two_words
mov d1,(a0+)
memset_4_two_words:
mov d1,(a0+)
memset_4_one_word:
mov d1,(a0+)
memset_4_no_remainder:
# check we set the correct amount
# TODO: REMOVE CHECK
sub e3,a0,d2
mov (20,sp),d1
cmp d2,d1
beq memset_done
break
break
break
memset_done:
mov e3,a0
ret [d2,d3],8
# handle misaligned copying
memset_1:
add -1,d2
mov +1,d3
setlb # setlb requires the next insns
# to occupy exactly 4 bytes
sub d3,d2
movbu d1,(a0)
inc a0
lcc
mov e3,a0
ret [d2,d3],8
memset_end:
.size memset, memset_end-memset
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