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/* memset/bzero -- set memory area to CH/0
Optimized version for x86-64.
Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Andreas Jaeger <aj@suse.de>.
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/>. */
#include "_glibc_inc.h"
/* BEWARE: `#ifdef memset' means that memset is redefined as `bzero' */
#define BZERO_P (defined memset)
/* This is somehow experimental and could made dependend on the cache
size. */
#define LARGE $120000
.text
#endif
ENTRY (memset)
#if BZERO_P
mov %rsi,%rdx /* Adjust parameter. */
xorl %esi,%esi /* Fill with 0s. */
#endif
cmp $0x7,%rdx /* Check for small length. */
mov %rdi,%rcx /* Save ptr as return value. */
jbe 7f
#if BZERO_P
mov %rsi,%r8 /* Just copy 0. */
#else
/* Populate 8 bit data to full 64-bit. */
movabs $0x0101010101010101,%r8
movzbl %sil,%eax
imul %rax,%r8
#endif
test $0x7,%edi /* Check for alignment. */
jz 2f
/* Next 3 insns are 9 bytes total, make sure we decode them in one go */
.p2align 4,,9
1:
/* Align ptr to 8 byte. */
mov %sil,(%rcx)
dec %rdx
inc %rcx
test $0x7,%cl
jnz 1b
2: /* Check for really large regions. */
mov %rdx,%rax
shr $0x6,%rax
je 4f
cmp LARGE, %rdx
jae 11f
/* Next 3 insns are 11 bytes total, make sure we decode them in one go */
.p2align 4,,11
3:
/* Fill 64 bytes. */
mov %r8,(%rcx)
mov %r8,0x8(%rcx)
mov %r8,0x10(%rcx)
mov %r8,0x18(%rcx)
mov %r8,0x20(%rcx)
mov %r8,0x28(%rcx)
mov %r8,0x30(%rcx)
mov %r8,0x38(%rcx)
add $0x40,%rcx
dec %rax
jne 3b
4: /* Fill final bytes. */
and $0x3f,%edx
mov %rdx,%rax
shr $0x3,%rax
je 6f
5: /* First in chunks of 8 bytes. */
mov %r8,(%rcx)
add $0x8,%rcx
dec %rax
jne 5b
6:
and $0x7,%edx
7:
test %rdx,%rdx
je 9f
8: /* And finally as bytes (up to 7). */
mov %sil,(%rcx)
inc %rcx
dec %rdx
jne 8b
9:
#if BZERO_P
/* nothing */
#else
/* Load result (only if used as memset). */
mov %rdi,%rax /* start address of destination is result */
#endif
retq
/* Next 3 insns are 14 bytes total, make sure we decode them in one go */
.p2align 4,,14
11:
/* Fill 64 bytes without polluting the cache. */
/* We could use movntdq %xmm0,(%rcx) here to further
speed up for large cases but let's not use XMM registers. */
movnti %r8,(%rcx)
movnti %r8,0x8(%rcx)
movnti %r8,0x10(%rcx)
movnti %r8,0x18(%rcx)
movnti %r8,0x20(%rcx)
movnti %r8,0x28(%rcx)
movnti %r8,0x30(%rcx)
movnti %r8,0x38(%rcx)
add $0x40,%rcx
dec %rax
jne 11b
jmp 4b
END (memset)
#if !BZERO_P
libc_hidden_def(memset)
#endif
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