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/*
* Copyright 2011 Tilera Corporation. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, version 2.
*
* 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, GOOD TITLE or
* NON INFRINGEMENT. See the GNU General Public License for
* more details.
*/
#include <arch/chip.h>
#include <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
#undef memset
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. */
/* KLUDGE */
v64 = 0x0101010101010101ULL * (uint8_t)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;
}
EXPORT_SYMBOL(memset);
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