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/* Copyright (C) 2012-2013 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
/* Assumptions:
*
* ARMv8-a, AArch64
* Unaligned accesses
*
*/
#define dstin x0
#define src x1
#define count x2
#define tmp1 x3
#define tmp1w w3
#define tmp2 x4
#define tmp2w w4
#define tmp3 x5
#define tmp3w w5
#define dst x6
#define A_l x7
#define A_h x8
#define B_l x9
#define B_h x10
#define C_l x11
#define C_h x12
#define D_l x13
#define D_h x14
#include <sysdep.h>
ENTRY_ALIGN (memcpy, 6)
mov dst, dstin
cmp count, #64
b.ge L(cpy_not_short)
cmp count, #15
b.le L(tail15tiny)
/* Deal with small copies quickly by dropping straight into the
* exit block. */
L(tail63):
/* Copy up to 48 bytes of data. At this point we only need the
* bottom 6 bits of count to be accurate. */
ands tmp1, count, #0x30
b.eq L(tail15)
add dst, dst, tmp1
add src, src, tmp1
cmp tmp1w, #0x20
b.eq 1f
b.lt 2f
ldp A_l, A_h, [src, #-48]
stp A_l, A_h, [dst, #-48]
1:
ldp A_l, A_h, [src, #-32]
stp A_l, A_h, [dst, #-32]
2:
ldp A_l, A_h, [src, #-16]
stp A_l, A_h, [dst, #-16]
L(tail15):
ands count, count, #15
beq 1f
add src, src, count
ldp A_l, A_h, [src, #-16]
add dst, dst, count
stp A_l, A_h, [dst, #-16]
1:
RET
L(tail15tiny):
/* Copy up to 15 bytes of data. Does not assume additional data
being copied. */
tbz count, #3, 1f
ldr tmp1, [src], #8
str tmp1, [dst], #8
1:
tbz count, #2, 1f
ldr tmp1w, [src], #4
str tmp1w, [dst], #4
1:
tbz count, #1, 1f
ldrh tmp1w, [src], #2
strh tmp1w, [dst], #2
1:
tbz count, #0, 1f
ldrb tmp1w, [src]
strb tmp1w, [dst]
1:
RET
L(cpy_not_short):
/* We don't much care about the alignment of DST, but we want SRC
* to be 128-bit (16 byte) aligned so that we don't cross cache line
* boundaries on both loads and stores. */
neg tmp2, src
ands tmp2, tmp2, #15 /* Bytes to reach alignment. */
b.eq 2f
sub count, count, tmp2
/* Copy more data than needed; it's faster than jumping
* around copying sub-Quadword quantities. We know that
* it can't overrun. */
ldp A_l, A_h, [src]
add src, src, tmp2
stp A_l, A_h, [dst]
add dst, dst, tmp2
/* There may be less than 63 bytes to go now. */
cmp count, #63
b.le L(tail63)
2:
subs count, count, #128
b.ge L(cpy_body_large)
/* Less than 128 bytes to copy, so handle 64 here and then jump
* to the tail. */
ldp A_l, A_h, [src]
ldp B_l, B_h, [src, #16]
ldp C_l, C_h, [src, #32]
ldp D_l, D_h, [src, #48]
stp A_l, A_h, [dst]
stp B_l, B_h, [dst, #16]
stp C_l, C_h, [dst, #32]
stp D_l, D_h, [dst, #48]
tst count, #0x3f
add src, src, #64
add dst, dst, #64
b.ne L(tail63)
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 6
L(cpy_body_large):
/* There are at least 128 bytes to copy. */
ldp A_l, A_h, [src, #0]
sub dst, dst, #16 /* Pre-bias. */
ldp B_l, B_h, [src, #16]
ldp C_l, C_h, [src, #32]
ldp D_l, D_h, [src, #48]! /* src += 64 - Pre-bias. */
1:
stp A_l, A_h, [dst, #16]
ldp A_l, A_h, [src, #16]
stp B_l, B_h, [dst, #32]
ldp B_l, B_h, [src, #32]
stp C_l, C_h, [dst, #48]
ldp C_l, C_h, [src, #48]
stp D_l, D_h, [dst, #64]!
ldp D_l, D_h, [src, #64]!
subs count, count, #64
b.ge 1b
stp A_l, A_h, [dst, #16]
stp B_l, B_h, [dst, #32]
stp C_l, C_h, [dst, #48]
stp D_l, D_h, [dst, #64]
add src, src, #16
add dst, dst, #64 + 16
tst count, #0x3f
b.ne L(tail63)
RET
END (memcpy)
libc_hidden_builtin_def (memcpy)
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