2005-04-07 03:56:03 +00:00
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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: bzero.S,v 1.2 2003/07/26 19:24:38 salo Exp $")
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#endif
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ENTRY(bzero)
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cld /* set fill direction forward */
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xorq %rax,%rax /* set fill data to 0 */
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/*
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* if the string is too short, it's really not worth the overhead
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* of aligning to word boundries, etc. So we jump to a plain
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* unaligned set.
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*/
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2005-04-07 05:46:46 +00:00
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cmpq $16,%rsi
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2005-04-07 03:56:03 +00:00
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jb L1
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movq %rdi,%rcx /* compute misalignment */
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negq %rcx
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andq $7,%rcx
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2005-04-07 05:46:46 +00:00
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subq %rcx,%rsi
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2005-04-07 03:56:03 +00:00
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rep /* zero until word aligned */
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stosb
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2005-04-07 05:46:46 +00:00
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movq %rsi,%rcx /* zero by words */
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2005-04-07 03:56:03 +00:00
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shrq $3,%rcx
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2005-04-07 05:46:46 +00:00
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andq $7,%rsi
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2005-04-07 03:56:03 +00:00
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rep
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stosq
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2005-04-07 05:46:46 +00:00
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L1: movq %rsi,%rcx /* zero remainder by bytes */
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2005-04-07 03:56:03 +00:00
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rep
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stosb
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ret
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