1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
|
/*
* 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 <linux/types.h>
#include <linux/string.h>
#include <linux/module.h>
#include <arch/chip.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;
}
EXPORT_SYMBOL(memset);
|
