1 /*
2 * Copyright (c) 2017 Imagination Technologies.
3 *
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 *
10 * * Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * * Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer
14 * in the documentation and/or other materials provided with
15 * the distribution.
16 * * Neither the name of Imagination Technologies nor the names of its
17 * contributors may be used to endorse or promote products derived
18 * from this software without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
21 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
23 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
24 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
25 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
26 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
27 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
28 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
29 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
30 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
31 */
32
33 #include <string.h>
34
35 #define op_t unsigned long int
36 #define op_size sizeof (op_t)
37
38 #if __mips64
39 typedef struct
40 {
41 op_t B0:8, B1:8, B2:8, B3:8, B4:8, B5:8, B6:8, B7:8;
42 } bits_t;
43 #else
44 typedef struct
45 {
46 op_t B0:8, B1:8, B2:8, B3:8;
47 } bits_t;
48 #endif
49
50 typedef union
51 {
52 op_t v;
53 bits_t b;
54 } bitfields_t;
55
56 #define DO_BYTE(i) \
57 if (a.b.B##i != ch) { \
58 if(a.b.B##i == '\0') return 0; \
59 p++; \
60 } else \
61 return (char *)p;
62
63 #define DO_WORD(w, cnt) { \
64 op_t val = w[cnt] ^ mask_c; \
65 if ((((w[cnt] - mask_1) & ~w[cnt]) & mask_128) || \
66 (((val - mask_1) & ~val) & mask_128)) { \
67 return do_bytes(w + cnt, ch); \
68 } \
69 }
70
71 static inline char * __attribute__ ((always_inline))
do_bytes(const op_t * w,unsigned char ch)72 do_bytes (const op_t* w, unsigned char ch)
73 {
74 bitfields_t a;
75 unsigned char* p = (unsigned char *) w;
76 a.v = *w;
77 #if __mips64
78 DO_BYTE(0)
79 DO_BYTE(1)
80 DO_BYTE(2)
81 DO_BYTE(3)
82 DO_BYTE(4)
83 DO_BYTE(5)
84 DO_BYTE(6)
85 DO_BYTE(7)
86 #else
87 DO_BYTE(0)
88 DO_BYTE(1)
89 DO_BYTE(2)
90 DO_BYTE(3)
91 #endif
92 return (char *)p;
93 }
94
strchr(const char * s,int c)95 char* strchr(const char* s, int c) __overloadable
96 {
97 const op_t *w;
98 op_t mask_1, mask_128, mask_c;
99 const unsigned char ch = c;
100 unsigned char* p = (unsigned char *) s;
101
102 /*
103 * Check byte by byte till initial alignment
104 */
105 for ( ; *p != ch && ((size_t) p % op_size) != 0; p++)
106 if (*p == '\0')
107 return 0;
108
109 if (*p != ch) {
110 w = (const op_t *) p;
111
112 mask_c = ch | (ch << 8);
113 mask_c |= mask_c << 16;
114 __asm__ volatile (
115 "li %0, 0x01010101 \n\t"
116 : "=r" (mask_1)
117 );
118 #if __mips64
119 mask_1 |= mask_1 << 32;
120 mask_c |= mask_c << 32;
121 #endif
122 mask_128 = mask_1 << 7;
123
124 /*
125 * Check word/dword wize after initial alignment till character match
126 * or end of string
127 */
128 while (1) {
129 DO_WORD(w, 0)
130 DO_WORD(w, 1)
131 DO_WORD(w, 2)
132 DO_WORD(w, 3)
133 w += 4;
134 }
135 }
136
137 return (char *)p;
138 }
139