Add machine-specific, optimized implementations of bcmp and memcmp.
PR: 73111 Submitted by: Ville-Pertti Keinonen <will@iki.fi> (taken from NetBSD) MFC after: 3 weeks
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=144782
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# $FreeBSD$
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MDSRCS+= bcopy.S bzero.S memcpy.S memmove.S memset.S
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MDSRCS+= bcmp.S bcopy.S bzero.S memcmp.S memcpy.S memmove.S memset.S
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25
lib/libc/amd64/string/bcmp.S
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25
lib/libc/amd64/string/bcmp.S
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#include <machine/asm.h>
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__FBSDID("$FreeBSD$");
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#if 0
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RCSID("$NetBSD: bcmp.S,v 1.1 2001/06/19 00:25:04 fvdl Exp $")
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#endif
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ENTRY(bcmp)
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xorl %eax,%eax /* clear return value */
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cld /* set compare direction forward */
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movq %rdx,%rcx /* compare by words */
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shrq $3,%rcx
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repe
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cmpsq
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jne L1
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movq %rdx,%rcx /* compare remainder by bytes */
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andq $7,%rcx
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repe
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cmpsb
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je L2
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L1: incl %eax
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L2: ret
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41
lib/libc/amd64/string/memcmp.S
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lib/libc/amd64/string/memcmp.S
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/*
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* Written by J.T. Conklin <jtc@NetBSD.org>.
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* Public domain.
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* Adapted for NetBSD/x86_64 by Frank van der Linden <fvdl@wasabisystems.com>
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*/
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#include <machine/asm.h>
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__FBSDID("$FreeBSD$");
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#if 0
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RCSID("$NetBSD: memcmp.S,v 1.2 2003/07/26 19:24:39 salo Exp $")
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#endif
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ENTRY(memcmp)
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cld /* set compare direction forward */
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movq %rdx,%rcx /* compare by longs */
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shrq $3,%rcx
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repe
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cmpsq
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jne L5 /* do we match so far? */
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movq %rdx,%rcx /* compare remainder by bytes */
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andq $7,%rcx
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repe
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cmpsb
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jne L6 /* do we match? */
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xorl %eax,%eax /* we match, return zero */
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ret
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L5: movl $8,%ecx /* We know that one of the next */
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subq %rcx,%rdi /* eight pairs of bytes do not */
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subq %rcx,%rsi /* match. */
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repe
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cmpsb
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L6: xorl %eax,%eax /* Perform unsigned comparison */
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movb -1(%rdi),%al
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xorl %edx,%edx
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movb -1(%rsi),%dl
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subl %edx,%eax
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ret
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