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freebsd
GitHub Repository: freebsd/freebsd-src
 Path: blob/main/contrib/arm-optimized-routines/string/arm/strcpy.c
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/*

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 * strcpy

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 *

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 * Copyright (c) 2008-2020, Arm Limited.

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 * SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception

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 */

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#if defined (__thumb2__) && !defined (__thumb__)

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/* For GLIBC:

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#include <string.h>

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#include <memcopy.h>

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#undef strcmp

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*/

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#ifdef __thumb2__

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#define magic1(REG) "#0x01010101"

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#define magic2(REG) "#0x80808080"

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#else

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#define magic1(REG) #REG

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

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#endif

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char* __attribute__((naked))

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__strcpy_arm (char* dst, const char* src)

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{

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  __asm__ (

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       "pld	[r1, #0]\n\t"

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

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       "mov	ip, r0\n\t"

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       "tst	r2, #3\n\t"

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       "bne	4f\n\t"

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       "tst	r1, #3\n\t"

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       "bne	3f\n"

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  "5:\n\t"

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# ifndef __thumb2__

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

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

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

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

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# endif

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

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       "tst	r1, #4\n\t"

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

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       "beq	2f\n\t"

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

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

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

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       "itt	eq\n\t"

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

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

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       "bne	1f\n\t"

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

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

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	  load stalls.  */

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       ".p2align 2\n"

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  "2:\n\t"

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       "pld	[r1, #8]\n\t"

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

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

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

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

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

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       "bne	1f\n\t"

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

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

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

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       "itt	eq\n\t"

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

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

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       "beq	2b\n\t"

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       "mov	r3, r4\n"

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  "1:\n\t"

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# ifdef __ARMEB__

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

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# endif

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

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

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# ifdef __ARMEL__

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

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# endif

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       "bne	1b\n\t"

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

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# ifndef __thumb2__

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

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# endif

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       "BX LR\n"

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

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	  not zero.  */

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  "3:\n\t"

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       "tst	r1, #1\n\t"

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       "beq	1f\n\t"

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

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

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       "cmp	r2, #0\n\t"

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       "it	eq\n"

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       "BXEQ LR\n"

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  "1:\n\t"

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       "tst	r1, #2\n\t"

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       "beq	5b\n\t"

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

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# ifdef __ARMEB__

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

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       "iteet	ne\n\t"

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

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

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

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

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# else

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

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       "itet	ne\n\t"

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

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

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

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# endif

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       "bne	5b\n\t"

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       "BX LR\n"

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

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	  byte copying.  */

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  "4:\n\t"

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

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

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       "cmp	r2, #0\n\t"

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       "bne	4b\n\t"

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       "BX LR");

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}

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/* For GLIBC: libc_hidden_builtin_def (strcpy) */

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#endif /* defined (__thumb2__) && !defined (__thumb__)  */

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