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/*
* Copyright (C) 2013 ARM Ltd.
* Copyright (C) 2013 Linaro.
*
* This code is based on glibc cortex strings work originally authored by Linaro
* and re-licensed under GPLv2 for the Linux kernel. The original code can
* be found @
*
* http://bazaar.launchpad.net/~linaro-toolchain-dev/cortex-strings/trunk/
* files/head:/src/aarch64/
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <linux/linkage.h>
#include <asm/assembler.h>
#include <asm/cache.h>
/*
* Fill in the buffer with character c (alignment handled by the hardware)
*
* Parameters:
* x0 - buf
* x1 - c
* x2 - n
* Returns:
* x0 - buf
*/
dstin .req x0
val .req w1
count .req x2
tmp1 .req x3
tmp1w .req w3
tmp2 .req x4
tmp2w .req w4
zva_len_x .req x5
zva_len .req w5
zva_bits_x .req x6
A_l .req x7
A_lw .req w7
dst .req x8
tmp3w .req w9
tmp3 .req x9
ENTRY(memset)
mov dst, dstin /* Preserve return value. */
and A_lw, val, #255
orr A_lw, A_lw, A_lw, lsl #8
orr A_lw, A_lw, A_lw, lsl #16
orr A_l, A_l, A_l, lsl #32
cmp count, #15
b.hi .Lover16_proc
/*All store maybe are non-aligned..*/
tbz count, #3, 1f
str A_l, [dst], #8
1:
tbz count, #2, 2f
str A_lw, [dst], #4
2:
tbz count, #1, 3f
strh A_lw, [dst], #2
3:
tbz count, #0, 4f
strb A_lw, [dst]
4:
ret
.Lover16_proc:
/*Whether the start address is aligned with 16.*/
neg tmp2, dst
ands tmp2, tmp2, #15
b.eq .Laligned
/*
* The count is not less than 16, we can use stp to store the start 16 bytes,
* then adjust the dst aligned with 16.This process will make the current
* memory address at alignment boundary.
*/
stp A_l, A_l, [dst] /*non-aligned store..*/
/*make the dst aligned..*/
sub count, count, tmp2
add dst, dst, tmp2
.Laligned:
cbz A_l, .Lzero_mem
.Ltail_maybe_long:
cmp count, #64
b.ge .Lnot_short
.Ltail63:
ands tmp1, count, #0x30
b.eq 3f
cmp tmp1w, #0x20
b.eq 1f
b.lt 2f
stp A_l, A_l, [dst], #16
1:
stp A_l, A_l, [dst], #16
2:
stp A_l, A_l, [dst], #16
/*
* The last store length is less than 16,use stp to write last 16 bytes.
* It will lead some bytes written twice and the access is non-aligned.
*/
3:
ands count, count, #15
cbz count, 4f
add dst, dst, count
stp A_l, A_l, [dst, #-16] /* Repeat some/all of last store. */
4:
ret
/*
* Critical loop. Start at a new cache line boundary. Assuming
* 64 bytes per line, this ensures the entire loop is in one line.
*/
.p2align L1_CACHE_SHIFT
.Lnot_short:
sub dst, dst, #16/* Pre-bias. */
sub count, count, #64
1:
stp A_l, A_l, [dst, #16]
stp A_l, A_l, [dst, #32]
stp A_l, A_l, [dst, #48]
stp A_l, A_l, [dst, #64]!
subs count, count, #64
b.ge 1b
tst count, #0x3f
add dst, dst, #16
b.ne .Ltail63
.Lexitfunc:
ret
/*
* For zeroing memory, check to see if we can use the ZVA feature to
* zero entire 'cache' lines.
*/
.Lzero_mem:
cmp count, #63
b.le .Ltail63
/*
* For zeroing small amounts of memory, it's not worth setting up
* the line-clear code.
*/
cmp count, #128
b.lt .Lnot_short /*count is at least 128 bytes*/
mrs tmp1, dczid_el0
tbnz tmp1, #4, .Lnot_short
mov tmp3w, #4
and zva_len, tmp1w, #15 /* Safety: other bits reserved. */
lsl zva_len, tmp3w, zva_len
ands tmp3w, zva_len, #63
/*
* ensure the zva_len is not less than 64.
* It is not meaningful to use ZVA if the block size is less than 64.
*/
b.ne .Lnot_short
.Lzero_by_line:
/*
* Compute how far we need to go to become suitably aligned. We're
* already at quad-word alignment.
*/
cmp count, zva_len_x
b.lt .Lnot_short /* Not enough to reach alignment. */
sub zva_bits_x, zva_len_x, #1
neg tmp2, dst
ands tmp2, tmp2, zva_bits_x
b.eq 2f /* Already aligned. */
/* Not aligned, check that there's enough to copy after alignment.*/
sub tmp1, count, tmp2
/*
* grantee the remain length to be ZVA is bigger than 64,
* avoid to make the 2f's process over mem range.*/
cmp tmp1, #64
ccmp tmp1, zva_len_x, #8, ge /* NZCV=0b1000 */
b.lt .Lnot_short
/*
* We know that there's at least 64 bytes to zero and that it's safe
* to overrun by 64 bytes.
*/
mov count, tmp1
1:
stp A_l, A_l, [dst]
stp A_l, A_l, [dst, #16]
stp A_l, A_l, [dst, #32]
subs tmp2, tmp2, #64
stp A_l, A_l, [dst, #48]
add dst, dst, #64
b.ge 1b
/* We've overrun a bit, so adjust dst downwards.*/
add dst, dst, tmp2
2:
sub count, count, zva_len_x
3:
dc zva, dst
add dst, dst, zva_len_x
subs count, count, zva_len_x
b.ge 3b
ands count, count, zva_bits_x
b.ne .Ltail_maybe_long
ret
ENDPROC(memset)
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