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/* Optimized memset for Xtensa.
Copyright (C) 2001, 2007 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, write to the Free
Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
Boston, MA 02110-1301, USA. */
#include "../../sysdeps/linux/xtensa/sysdep.h"
#include <bits/xtensa-config.h>
/* Do not use .literal_position in the ENTRY macro. */
#undef LITERAL_POSITION
#define LITERAL_POSITION
/* void *memset (void *dst, int c, size_t length)
The algorithm is as follows:
Create a word with c in all byte positions.
If the destination is aligned, set 16B chunks with a loop, and then
finish up with 8B, 4B, 2B, and 1B stores conditional on the length.
If the destination is unaligned, align it by conditionally
setting 1B and/or 2B and then go to aligned case.
This code tries to use fall-through branches for the common
case of an aligned destination (except for the branches to
the alignment labels). */
/* Byte-by-byte set. */
.text
.align 4
.literal_position
__memset_aux:
/* Skip a byte to get 1 mod 4 alignment for LOOPNEZ
(0 mod 4 alignment for LBEG). */
.byte 0
.Lbyteset:
#if XCHAL_HAVE_LOOPS
loopnez a4, 2f
#else
beqz a4, 2f
add a6, a5, a4 /* a6 = ending address */
#endif
1: s8i a3, a5, 0
addi a5, a5, 1
#if !XCHAL_HAVE_LOOPS
blt a5, a6, 1b
#endif
2: retw
/* Destination is unaligned. */
.align 4
.Ldst1mod2: /* dst is only byte aligned */
/* Do short sizes byte-by-byte. */
bltui a4, 8, .Lbyteset
/* Set 1 byte. */
s8i a3, a5, 0
addi a5, a5, 1
addi a4, a4, -1
/* Now retest if dst is aligned. */
_bbci.l a5, 1, .Ldstaligned
.Ldst2mod4: /* dst has 16-bit alignment */
/* Do short sizes byte-by-byte. */
bltui a4, 8, .Lbyteset
/* Set 2 bytes. */
s16i a3, a5, 0
addi a5, a5, 2
addi a4, a4, -2
/* dst is now aligned; return to main algorithm */
j .Ldstaligned
ENTRY (memset)
/* a2 = dst, a3 = c, a4 = length */
/* Duplicate character into all bytes of word. */
extui a3, a3, 0, 8
slli a7, a3, 8
or a3, a3, a7
slli a7, a3, 16
or a3, a3, a7
mov a5, a2 /* copy dst so that a2 is return value */
/* Check if dst is unaligned. */
_bbsi.l a2, 0, .Ldst1mod2
_bbsi.l a2, 1, .Ldst2mod4
.Ldstaligned:
/* Get number of loop iterations with 16B per iteration. */
srli a7, a4, 4
/* Destination is word-aligned. */
#if XCHAL_HAVE_LOOPS
loopnez a7, 2f
#else
beqz a7, 2f
slli a6, a7, 4
add a6, a6, a5 /* a6 = end of last 16B chunk */
#endif
/* Set 16 bytes per iteration. */
1: s32i a3, a5, 0
s32i a3, a5, 4
s32i a3, a5, 8
s32i a3, a5, 12
addi a5, a5, 16
#if !XCHAL_HAVE_LOOPS
blt a5, a6, 1b
#endif
/* Set any leftover pieces smaller than 16B. */
2: bbci.l a4, 3, 3f
/* Set 8 bytes. */
s32i a3, a5, 0
s32i a3, a5, 4
addi a5, a5, 8
3: bbci.l a4, 2, 4f
/* Set 4 bytes. */
s32i a3, a5, 0
addi a5, a5, 4
4: bbci.l a4, 1, 5f
/* Set 2 bytes. */
s16i a3, a5, 0
addi a5, a5, 2
5: bbci.l a4, 0, 6f
/* Set 1 byte. */
s8i a3, a5, 0
6: retw
libc_hidden_def (memset)
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