libc/AOR_v20.02/string/arm/strcpy.c

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