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
|
#if defined __thumb__
#include "../../string/memchr.c"
#else
#include <string.h>
#include "xscale.h"
void *
memchr (const void *start, int c, size_t len)
{
const char *str = start;
if (len == 0)
return 0;
asm (PRELOADSTR ("%0") : : "r" (start));
c &= 0xff;
#ifndef __OPTIMIZE_SIZE__
/* Skip unaligned part. */
if ((long)str & 3)
{
str--;
do
{
if (*++str == c)
return (void *)str;
}
while (((long)str & 3) != 0 && --len > 0);
}
if (len > 3)
{
unsigned int c2 = c + (c << 8);
c2 += c2 << 16;
/* Load two constants:
R7 = 0xfefefeff [ == ~(0x80808080 << 1) ]
R6 = 0x80808080 */
asm (
"mov r6, #0x80
add r6, r6, #0x8000
add r6, r6, r6, lsl #16
mvn r7, r6, lsl #1
0:
cmp %1, #0x7
bls 1f
ldmia %0!, { r3, r9 }
" PRELOADSTR ("%0") "
sub %1, %1, #8
eor r3, r3, %2
eor r9, r9, %2
add r2, r3, r7
add r8, r9, r7
bic r2, r2, r3
bic r8, r8, r9
and r1, r2, r6
and r9, r8, r6
orrs r1, r1, r9
beq 0b
add %1, %1, #8
sub %0, %0, #8
1:
cmp %1, #0x3
bls 2f
ldr r3, [%0], #4
" PRELOADSTR ("%0") "
sub %1, %1, #4
eor r3, r3, %2
add r2, r3, r7
bic r2, r2, r3
ands r1, r2, r6
beq 1b
sub %0, %0, #4
add %1, %1, #4
2:
"
: "=&r" (str), "=&r" (len)
: "r" (c2), "0" (str), "1" (len)
: "r1", "r2", "r3", "r6", "r7", "r8", "r9", "cc");
}
#endif
while (len-- > 0)
{
if (*str == c)
return (void *)str;
str++;
}
return 0;
}
#endif
|
