| 1 | /* |
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| 2 | * strcpy |
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| 3 | * |
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| 4 | * Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 5 | * See https://llvm.org/LICENSE.txt for license information. |
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| 6 | * SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 7 | */ |
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| 8 | |
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| 9 | #if defined (__thumb2__) && !defined (__thumb__) |
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| 10 | |
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| 11 | /* For GLIBC: |
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| 12 | #include <string.h> |
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| 13 | #include <memcopy.h> |
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| 14 | |
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| 15 | #undef strcmp |
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| 16 | */ |
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| 17 | |
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| 18 | #ifdef __thumb2__ |
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| 19 | #define magic1(REG) "#0x01010101" |
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| 20 | #define magic2(REG) "#0x80808080" |
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| 21 | #else |
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| 22 | #define magic1(REG) #REG |
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| 23 | #define magic2(REG) #REG ", lsl #7" |
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| 24 | #endif |
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| 25 | |
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| 26 | char* __attribute__((naked)) |
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| 27 | __strcpy_arm (char* dst, const char* src) |
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| 28 | { |
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| 29 | __asm__ ( |
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| 30 | "pld [r1, #0]\n\t" |
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| 31 | "eor r2, r0, r1\n\t" |
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| 32 | "mov ip, r0\n\t" |
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| 33 | "tst r2, #3\n\t" |
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| 34 | "bne 4f\n\t" |
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| 35 | "tst r1, #3\n\t" |
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| 36 | "bne 3f\n" |
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| 37 | "5:\n\t" |
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| 38 | # ifndef __thumb2__ |
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| 39 | "str r5, [sp, #-4]!\n\t" |
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| 40 | "mov r5, #0x01\n\t" |
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| 41 | "orr r5, r5, r5, lsl #8\n\t" |
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| 42 | "orr r5, r5, r5, lsl #16\n\t" |
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| 43 | # endif |
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| 44 | |
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| 45 | "str r4, [sp, #-4]!\n\t" |
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| 46 | "tst r1, #4\n\t" |
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| 47 | "ldr r3, [r1], #4\n\t" |
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| 48 | "beq 2f\n\t" |
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| 49 | "sub r2, r3, " magic1(r5)"\n\t" |
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| 50 | "bics r2, r2, r3\n\t" |
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| 51 | "tst r2, " magic2(r5)"\n\t" |
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| 52 | "itt eq\n\t" |
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| 53 | "streq r3, [ip], #4\n\t" |
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| 54 | "ldreq r3, [r1], #4\n" |
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| 55 | "bne 1f\n\t" |
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| 56 | /* Inner loop. We now know that r1 is 64-bit aligned, so we |
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| 57 | can safely fetch up to two words. This allows us to avoid |
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| 58 | load stalls. */ |
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| 59 | ".p2align 2\n" |
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| 60 | "2:\n\t" |
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| 61 | "pld [r1, #8]\n\t" |
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| 62 | "ldr r4, [r1], #4\n\t" |
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| 63 | "sub r2, r3, " magic1(r5)"\n\t" |
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| 64 | "bics r2, r2, r3\n\t" |
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| 65 | "tst r2, " magic2(r5)"\n\t" |
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| 66 | "sub r2, r4, " magic1(r5)"\n\t" |
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| 67 | "bne 1f\n\t" |
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| 68 | "str r3, [ip], #4\n\t" |
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| 69 | "bics r2, r2, r4\n\t" |
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| 70 | "tst r2, " magic2(r5)"\n\t" |
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| 71 | "itt eq\n\t" |
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| 72 | "ldreq r3, [r1], #4\n\t" |
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| 73 | "streq r4, [ip], #4\n\t" |
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| 74 | "beq 2b\n\t" |
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| 75 | "mov r3, r4\n" |
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| 76 | "1:\n\t" |
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| 77 | # ifdef __ARMEB__ |
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| 78 | "rors r3, r3, #24\n\t" |
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| 79 | # endif |
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| 80 | "strb r3, [ip], #1\n\t" |
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| 81 | "tst r3, #0xff\n\t" |
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| 82 | # ifdef __ARMEL__ |
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| 83 | "ror r3, r3, #8\n\t" |
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| 84 | # endif |
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| 85 | "bne 1b\n\t" |
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| 86 | "ldr r4, [sp], #4\n\t" |
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| 87 | # ifndef __thumb2__ |
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| 88 | "ldr r5, [sp], #4\n\t" |
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| 89 | # endif |
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| 90 | "BX LR\n" |
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| 91 | |
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| 92 | /* Strings have the same offset from word alignment, but it's |
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| 93 | not zero. */ |
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| 94 | "3:\n\t" |
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| 95 | "tst r1, #1\n\t" |
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| 96 | "beq 1f\n\t" |
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| 97 | "ldrb r2, [r1], #1\n\t" |
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| 98 | "strb r2, [ip], #1\n\t" |
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| 99 | "cmp r2, #0\n\t" |
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| 100 | "it eq\n" |
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| 101 | "BXEQ LR\n" |
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| 102 | "1:\n\t" |
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| 103 | "tst r1, #2\n\t" |
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| 104 | "beq 5b\n\t" |
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| 105 | "ldrh r2, [r1], #2\n\t" |
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| 106 | # ifdef __ARMEB__ |
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| 107 | "tst r2, #0xff00\n\t" |
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| 108 | "iteet ne\n\t" |
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| 109 | "strneh r2, [ip], #2\n\t" |
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| 110 | "lsreq r2, r2, #8\n\t" |
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| 111 | "streqb r2, [ip]\n\t" |
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| 112 | "tstne r2, #0xff\n\t" |
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| 113 | # else |
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| 114 | "tst r2, #0xff\n\t" |
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| 115 | "itet ne\n\t" |
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| 116 | "strneh r2, [ip], #2\n\t" |
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| 117 | "streqb r2, [ip]\n\t" |
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| 118 | "tstne r2, #0xff00\n\t" |
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| 119 | # endif |
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| 120 | "bne 5b\n\t" |
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| 121 | "BX LR\n" |
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| 122 | |
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| 123 | /* src and dst do not have a common word-alignment. Fall back to |
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| 124 | byte copying. */ |
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| 125 | "4:\n\t" |
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| 126 | "ldrb r2, [r1], #1\n\t" |
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| 127 | "strb r2, [ip], #1\n\t" |
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| 128 | "cmp r2, #0\n\t" |
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| 129 | "bne 4b\n\t" |
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| 130 | "BX LR" ); |
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| 131 | } |
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| 132 | /* For GLIBC: libc_hidden_builtin_def (strcpy) */ |
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| 133 | |
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| 134 | #endif /* defined (__thumb2__) && !defined (__thumb__) */ |
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| 135 | |
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