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/* Copyright (C) 2011-2012 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
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 <arch/chip.h>
#include <string.h>
#include <stdint.h>
#include "string-endian.h"
void *
__memset (void *s, int c, size_t n)
{
uint64_t *out64;
int n64, to_align64;
uint64_t v64;
uint8_t *out8 = s;
/* Experimentation shows that a trivial tight loop is a win up until
around a size of 20, where writing a word at a time starts to win. */
#define BYTE_CUTOFF 20
#if BYTE_CUTOFF < 7
/* This must be at least at least this big, or some code later
on doesn't work. */
# error "BYTE_CUTOFF is too small."
#endif
if (n < BYTE_CUTOFF)
{
/* Strangely, this turns out to be the tightest way to write
this loop. */
if (n != 0)
{
do
{
/* Strangely, combining these into one line performs worse. */
*out8 = c;
out8++;
}
while (--n != 0);
}
return s;
}
/* Align 'out8'. We know n >= 7 so this won't write past the end. */
while (((uintptr_t) out8 & 7) != 0)
{
*out8++ = c;
--n;
}
/* Align 'n'. */
while (n & 7)
out8[--n] = c;
out64 = (uint64_t *) out8;
n64 = n >> 3;
/* Tile input byte out to 64 bits. */
v64 = copy_byte(c);
/* This must be at least 8 or the following loop doesn't work. */
#define CACHE_LINE_SIZE_IN_DOUBLEWORDS (CHIP_L2_LINE_SIZE() / 8)
/* Determine how many words we need to emit before the 'out32'
pointer becomes aligned modulo the cache line size. */
to_align64 = (-((uintptr_t) out64 >> 3)) &
(CACHE_LINE_SIZE_IN_DOUBLEWORDS - 1);
/* Only bother aligning and using wh64 if there is at least
one full cache line to process. This check also prevents
overrunning the end of the buffer with alignment words. */
if (to_align64 <= n64 - CACHE_LINE_SIZE_IN_DOUBLEWORDS)
{
int lines_left;
/* Align out64 mod the cache line size so we can use wh64. */
n64 -= to_align64;
for (; to_align64 != 0; to_align64--)
{
*out64 = v64;
out64++;
}
/* Use unsigned divide to turn this into a right shift. */
lines_left = (unsigned) n64 / CACHE_LINE_SIZE_IN_DOUBLEWORDS;
do
{
/* Only wh64 a few lines at a time, so we don't exceed the
maximum number of victim lines. */
int x = ((lines_left < CHIP_MAX_OUTSTANDING_VICTIMS ()) ? lines_left
: CHIP_MAX_OUTSTANDING_VICTIMS ());
uint64_t *wh = out64;
int i = x;
int j;
lines_left -= x;
do
{
__insn_wh64 (wh);
wh += CACHE_LINE_SIZE_IN_DOUBLEWORDS;
}
while (--i);
for (j = x * (CACHE_LINE_SIZE_IN_DOUBLEWORDS / 4); j != 0; j--)
{
*out64++ = v64;
*out64++ = v64;
*out64++ = v64;
*out64++ = v64;
}
}
while (lines_left != 0);
/* We processed all full lines above, so only this many
words remain to be processed. */
n64 &= CACHE_LINE_SIZE_IN_DOUBLEWORDS - 1;
}
/* Now handle any leftover values. */
if (n64 != 0)
{
do
{
*out64 = v64;
out64++;
}
while (--n64 != 0);
}
return s;
}
weak_alias (__memset, memset)
libc_hidden_builtin_def (memset)
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