1 /*
2 * strcpy
3 *
4 * Copyright (c) 2008-2020, Arm Limited.
5 * SPDX-License-Identifier: MIT
6 */
7
8 /* For GLIBC:
9 #include <string.h>
10 #include <memcopy.h>
11
12 #undef strcmp
13 */
14
15 #ifdef __thumb2__
16 #define magic1(REG) "#0x01010101"
17 #define magic2(REG) "#0x80808080"
18 #else
19 #define magic1(REG) #REG
20 #define magic2(REG) #REG ", lsl #7"
21 #endif
22
23 char* __attribute__((naked))
__strcpy_arm(char * dst,const char * src)24 __strcpy_arm (char* dst, const char* src)
25 {
26 __asm__ (
27 "pld [r1, #0]\n\t"
28 "eor r2, r0, r1\n\t"
29 "mov ip, r0\n\t"
30 "tst r2, #3\n\t"
31 "bne 4f\n\t"
32 "tst r1, #3\n\t"
33 "bne 3f\n"
34 "5:\n\t"
35 # ifndef __thumb2__
36 "str r5, [sp, #-4]!\n\t"
37 "mov r5, #0x01\n\t"
38 "orr r5, r5, r5, lsl #8\n\t"
39 "orr r5, r5, r5, lsl #16\n\t"
40 # endif
41
42 "str r4, [sp, #-4]!\n\t"
43 "tst r1, #4\n\t"
44 "ldr r3, [r1], #4\n\t"
45 "beq 2f\n\t"
46 "sub r2, r3, "magic1(r5)"\n\t"
47 "bics r2, r2, r3\n\t"
48 "tst r2, "magic2(r5)"\n\t"
49 "itt eq\n\t"
50 "streq r3, [ip], #4\n\t"
51 "ldreq r3, [r1], #4\n"
52 "bne 1f\n\t"
53 /* Inner loop. We now know that r1 is 64-bit aligned, so we
54 can safely fetch up to two words. This allows us to avoid
55 load stalls. */
56 ".p2align 2\n"
57 "2:\n\t"
58 "pld [r1, #8]\n\t"
59 "ldr r4, [r1], #4\n\t"
60 "sub r2, r3, "magic1(r5)"\n\t"
61 "bics r2, r2, r3\n\t"
62 "tst r2, "magic2(r5)"\n\t"
63 "sub r2, r4, "magic1(r5)"\n\t"
64 "bne 1f\n\t"
65 "str r3, [ip], #4\n\t"
66 "bics r2, r2, r4\n\t"
67 "tst r2, "magic2(r5)"\n\t"
68 "itt eq\n\t"
69 "ldreq r3, [r1], #4\n\t"
70 "streq r4, [ip], #4\n\t"
71 "beq 2b\n\t"
72 "mov r3, r4\n"
73 "1:\n\t"
74 # ifdef __ARMEB__
75 "rors r3, r3, #24\n\t"
76 # endif
77 "strb r3, [ip], #1\n\t"
78 "tst r3, #0xff\n\t"
79 # ifdef __ARMEL__
80 "ror r3, r3, #8\n\t"
81 # endif
82 "bne 1b\n\t"
83 "ldr r4, [sp], #4\n\t"
84 # ifndef __thumb2__
85 "ldr r5, [sp], #4\n\t"
86 # endif
87 "BX LR\n"
88
89 /* Strings have the same offset from word alignment, but it's
90 not zero. */
91 "3:\n\t"
92 "tst r1, #1\n\t"
93 "beq 1f\n\t"
94 "ldrb r2, [r1], #1\n\t"
95 "strb r2, [ip], #1\n\t"
96 "cmp r2, #0\n\t"
97 "it eq\n"
98 "BXEQ LR\n"
99 "1:\n\t"
100 "tst r1, #2\n\t"
101 "beq 5b\n\t"
102 "ldrh r2, [r1], #2\n\t"
103 # ifdef __ARMEB__
104 "tst r2, #0xff00\n\t"
105 "iteet ne\n\t"
106 "strneh r2, [ip], #2\n\t"
107 "lsreq r2, r2, #8\n\t"
108 "streqb r2, [ip]\n\t"
109 "tstne r2, #0xff\n\t"
110 # else
111 "tst r2, #0xff\n\t"
112 "itet ne\n\t"
113 "strneh r2, [ip], #2\n\t"
114 "streqb r2, [ip]\n\t"
115 "tstne r2, #0xff00\n\t"
116 # endif
117 "bne 5b\n\t"
118 "BX LR\n"
119
120 /* src and dst do not have a common word-alignement. Fall back to
121 byte copying. */
122 "4:\n\t"
123 "ldrb r2, [r1], #1\n\t"
124 "strb r2, [ip], #1\n\t"
125 "cmp r2, #0\n\t"
126 "bne 4b\n\t"
127 "BX LR");
128 }
129 /* For GLIBC: libc_hidden_builtin_def (strcpy) */
130