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/*

 * Copyright (c) 2008 ARM Ltd

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. The name of the company may not be used to endorse or promote

 *    products derived from this software without specific prior written

 *    permission.

 *

 * THIS SOFTWARE IS PROVIDED BY ARM LTD ``AS IS'' AND ANY EXPRESS OR IMPLIED

 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF

 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

 * IN NO EVENT SHALL ARM LTD BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,

 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED

 * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR

 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF

 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING

 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS

 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

 */

#include "arm_asm.h"

#include <_ansi.h>

#include <string.h>

#ifdef __thumb2__

#define magic1(REG) "#0x01010101"

#define magic2(REG) "#0x80808080"

#else

#define magic1(REG) #REG

#define magic2(REG) #REG ", lsl #7"

#endif

char* __attribute__((naked))

strcpy (char* dst, const char* src)

{

  asm (

#if !(defined(__OPTIMIZE_SIZE__) || defined (PREFER_SIZE_OVER_SPEED) || \

      (defined (__thumb__) && !defined (__thumb2__)))

       "optpld  r1\n\t"

       "eor     r2, r0, r1\n\t"

       "mov     ip, r0\n\t"

       "tst     r2, #3\n\t"

       "bne     4f\n\t"

       "tst     r1, #3\n\t"

       "bne     3f\n"

  "5:\n\t"

#ifndef __thumb2__

       "str     r5, [sp, #-4]!\n\t"

       "mov     r5, #0x01\n\t"

       "orr     r5, r5, r5, lsl #8\n\t"

       "orr     r5, r5, r5, lsl #16\n\t"

#endif

       "str     r4, [sp, #-4]!\n\t"

       "tst     r1, #4\n\t"

       "ldr     r3, [r1], #4\n\t"

       "beq     2f\n\t"

       "sub     r2, r3, "magic1(r5)"\n\t"

       "bics    r2, r2, r3\n\t"

       "tst     r2, "magic2(r5)"\n\t"

       "itt     eq\n\t"

       "streq   r3, [ip], #4\n\t"

       "ldreq   r3, [r1], #4\n"

       "bne     1f\n\t"

       /* Inner loop.  We now know that r1 is 64-bit aligned, so we

          can safely fetch up to two words.  This allows us to avoid

          load stalls.  */

       ".p2align 2\n"

  "2:\n\t"

       "optpld  r1, #8\n\t"

       "ldr     r4, [r1], #4\n\t"

       "sub     r2, r3, "magic1(r5)"\n\t"

       "bics    r2, r2, r3\n\t"

       "tst     r2, "magic2(r5)"\n\t"

       "sub     r2, r4, "magic1(r5)"\n\t"

       "bne     1f\n\t"

       "str     r3, [ip], #4\n\t"

       "bics    r2, r2, r4\n\t"

       "tst     r2, "magic2(r5)"\n\t"

       "itt     eq\n\t"

       "ldreq   r3, [r1], #4\n\t"

       "streq   r4, [ip], #4\n\t"

       "beq     2b\n\t"

       "mov     r3, r4\n"

  "1:\n\t"

#ifdef __ARMEB__

       "rors    r3, r3, #24\n\t"

#endif

       "strb    r3, [ip], #1\n\t"

       "tst     r3, #0xff\n\t"

#ifdef __ARMEL__

       "ror     r3, r3, #8\n\t"

#endif

       "bne     1b\n\t"

       "ldr     r4, [sp], #4\n\t"

#ifndef __thumb2__

       "ldr     r5, [sp], #4\n\t"

#endif

       "RETURN\n"

       /* Strings have the same offset from word alignment, but it's

          not zero.  */

  "3:\n\t"

       "tst     r1, #1\n\t"

       "beq     1f\n\t"

       "ldrb    r2, [r1], #1\n\t"

       "strb    r2, [ip], #1\n\t"

       "cmp     r2, #0\n\t"

       "it      eq\n"

       "RETURN  eq\n"

  "1:\n\t"

       "tst     r1, #2\n\t"

       "beq     5b\n\t"

       "ldrh    r2, [r1], #2\n\t"

#ifdef __ARMEB__

       "tst     r2, #0xff00\n\t"

       "iteet   ne\n\t"

       "strneh  r2, [ip], #2\n\t"

       "lsreq   r2, r2, #8\n\t"

       "streqb  r2, [ip]\n\t"

       "tstne   r2, #0xff\n\t"

#else

       "tst     r2, #0xff\n\t"

       "itet    ne\n\t"

       "strneh  r2, [ip], #2\n\t"

       "streqb  r2, [ip]\n\t"

       "tstne   r2, #0xff00\n\t"

#endif

       "bne     5b\n\t"

       "RETURN\n"

       /* src and dst do not have a common word-alignement.  Fall back to

          byte copying.  */

  "4:\n\t"

       "ldrb    r2, [r1], #1\n\t"

       "strb    r2, [ip], #1\n\t"

       "cmp     r2, #0\n\t"

       "bne     4b\n\t"

       "RETURN"

#elif !defined (__thumb__) || defined (__thumb2__)

       "mov     r3, r0\n\t"

  "1:\n\t"

       "ldrb    r2, [r1], #1\n\t"

       "strb    r2, [r3], #1\n\t"

       "cmp     r2, #0\n\t"

       "bne     1b\n\t"

       "RETURN"

#else

       "mov     r3, r0\n\t"

  "1:\n\t"

       "ldrb    r2, [r1]\n\t"

       "add     r1, r1, #1\n\t"

       "strb    r2, [r3]\n\t"

       "add     r3, r3, #1\n\t"

       "cmp     r2, #0\n\t"

       "bne     1b\n\t"

       "RETURN"

#endif

       );

}