66 lines
1.2 KiB
ArmAsm
66 lines
1.2 KiB
ArmAsm
/*
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* Written by J.T. Conklin <jtc@netbsd.org>.
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* Public domain.
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* Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
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*/
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#include <machine/asm.h>
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#if defined(LIBC_SCCS)
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RCSID("$NetBSD: strcat.S,v 1.1 2001/06/19 00:25:05 fvdl Exp $")
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#endif
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/*
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* NOTE: I've unrolled the loop eight times: large enough to make a
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* significant difference, and small enough not to totally trash the
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* cache.
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*/
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ENTRY(strcat)
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movq %rdi,%r11
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cld /* set search forward */
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xorl %eax,%eax /* set search for null terminator */
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movq $-1,%rcx /* set search for lots of characters */
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repne /* search! */
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scasb
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decq %rdi
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L1: movb (%rsi),%al /* unroll loop, but not too much */
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movb %al,(%rdi)
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testb %al,%al
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jz L2
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movb 1(%rsi),%al
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movb %al,1(%rdi)
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testb %al,%al
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jz L2
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movb 2(%rsi),%al
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movb %al,2(%rdi)
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testb %al,%al
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jz L2
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movb 3(%rsi),%al
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movb %al,3(%rdi)
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testb %al,%al
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jz L2
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movb 4(%rsi),%al
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movb %al,4(%rdi)
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testb %al,%al
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jz L2
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movb 5(%rsi),%al
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movb %al,5(%rdi)
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testb %al,%al
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jz L2
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movb 6(%rsi),%al
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movb %al,6(%rdi)
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testb %al,%al
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jz L2
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movb 7(%rsi),%al
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movb %al,7(%rdi)
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addq $8,%rsi
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addq $8,%rdi
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testb %al,%al
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jnz L1
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L2: movq %r11,%rax
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ret
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