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\n\
add r6, r6, #0x8000\n\
add r6, r6, r6, lsl #16\n\
mvn r7, r6, lsl #1\n\
\n\
0:\n\
cmp %1, #0x7\n\
bls 1f\n\
\n\
ldmia %0!, { r3, r9 }\n\
" PRELOADSTR ("%0") "\n\
sub %1, %1, #8\n\
eor r3, r3, %2\n\
eor r9, r9, %2\n\
add r2, r3, r7\n\
add r8, r9, r7\n\
bic r2, r2, r3\n\
bic r8, r8, r9\n\
and r1, r2, r6\n\
and r9, r8, r6\n\
orrs r1, r1, r9\n\
beq 0b\n\
\n\
add %1, %1, #8\n\
sub %0, %0, #8\n\
1:\n\
cmp %1, #0x3\n\
bls 2f\n\
\n\
ldr r3, [%0], #4\n\
" PRELOADSTR ("%0") "\n\
sub %1, %1, #4\n\
eor r3, r3, %2\n\
add r2, r3, r7\n\
bic r2, r2, r3\n\
ands r1, r2, r6\n\
beq 1b\n\
\n\
sub %0, %0, #4\n\
add %1, %1, #4\n\
2:\n\
"
: "=&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
|
