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135 lines
3.2 KiB
135 lines
3.2 KiB
/*
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* strcpy
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*
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* Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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* See https://llvm.org/LICENSE.txt for license information.
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* SPDX-License-Identifier: 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-alignment. 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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