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/*
* strcpy
*
* Copyright (c) 2008-2020, Arm Limited.
* SPDX-License-Identifier: MIT OR Apache-2.0 WITH LLVM-exception
*/
#if defined (__thumb2__) && !defined (__thumb__)
/* For GLIBC:
#include <string.h>
#include <memcopy.h>
#undef strcmp
*/
#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_arm (char* dst, const char* src)
{
__asm__ (
"pld [r1, #0]\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"
"pld [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
"BX LR\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"
"BXEQ LR\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"
"BX LR\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"
"BX LR");
}
/* For GLIBC: libc_hidden_builtin_def (strcpy) */
#endif /* defined (__thumb2__) && !defined (__thumb__) */
|
