NetBSD/lib/libc/arch/i386/string/bzero.S

/*
 * Written by J.T. Conklin <jtc@netbsd.org>.
 * Public domain.
 */

#include <machine/asm.h>

#if defined(LIBC_SCCS)
	RCSID("$Id: bzero.S,v 1.7 1995/04/28 22:54:05 jtc Exp $")
#endif

ENTRY(bzero)
	pushl	%edi
	movl	8(%esp),%edi
	movl	12(%esp),%edx

	cld				/* set fill direction forward */
	xorl	%eax,%eax		/* set fill data to 0 */

	/*
	 * if the string is too short, it's really not worth the overhead
	 * of aligning to word boundries, etc.  So we jump to a plain
	 * unaligned set.
	 */
	cmpl	$16,%edx
	jb	L1

	movl	%edi,%ecx		/* compute misalignment */
	negl	%ecx
	andl	$3,%ecx
	subl	%ecx,%edx
	rep				/* zero until word aligned */
	stosb

	movl	%edx,%ecx		/* zero by words */
	shrl	$2,%ecx
	andl	$3,%edx
	rep
	stosl

L1:	movl	%edx,%ecx		/* zero remainder by bytes */
	rep
	stosb

	popl	%edi
	ret
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00			`/*`
Winning Strategies has placed this code into the Public Domain 1995-04-29 02:53:59 +04:00			`* Written by J.T. Conklin <jtc@netbsd.org>.`
			`* Public domain.`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00			`*/`

Use RCSID macro for RCS ID's. 1994-03-12 04:39:55 +03:00			`#include <machine/asm.h>`

Change instances of LIBC_RCS back to LIBC_SCCS. If we are going to change th LIBC_RCS, the entire source tree should be updated at once. Remove && !defined(lint) from conditionals around rcs id's. No one is ever going to pass a *.s file through lint. 1993-10-21 04:39:55 +03:00			`#if defined(LIBC_SCCS)`
Winning Strategies has placed this code into the Public Domain 1995-04-29 02:53:59 +04:00			`RCSID("$Id: bzero.S,v 1.7 1995/04/28 22:54:05 jtc Exp $")`
Change instances of LIBC_RCS back to LIBC_SCCS. If we are going to change th LIBC_RCS, the entire source tree should be updated at once. Remove && !defined(lint) from conditionals around rcs id's. No one is ever going to pass a *.s file through lint. 1993-10-21 04:39:55 +03:00			`#endif`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00
			`ENTRY(bzero)`
			`pushl %edi`
Optimize better. 1995-02-05 17:58:44 +03:00			`movl 8(%esp),%edi`
			`movl 12(%esp),%edx`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00
			`cld /* set fill direction forward */`
			`xorl %eax,%eax /* set fill data to 0 */`

			`/*`
			`* if the string is too short, it's really not worth the overhead`
So many files in arch/i386 have been changed I might as well run my remove unecessary trailing whitespace script. 1993-10-21 04:48:14 +03:00			`* of aligning to word boundries, etc. So we jump to a plain`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00			`* unaligned set.`
			`*/`
Optimize better. 1995-02-05 17:58:44 +03:00			`cmpl $16,%edx`
			`jb L1`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00
Optimize better. 1995-02-05 17:58:44 +03:00			`movl %edi,%ecx /* compute misalignment */`
			`negl %ecx`
			`andl $3,%ecx`
			`subl %ecx,%edx`
			`rep /* zero until word aligned */`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00			`stosb`

Optimize better. 1995-02-05 17:58:44 +03:00			`movl %edx,%ecx /* zero by words */`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00			`shrl $2,%ecx`
Optimize better. 1995-02-05 17:58:44 +03:00			`andl $3,%edx`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00			`rep`
			`stosl`

Optimize better. 1995-02-05 17:58:44 +03:00			`L1: movl %edx,%ecx /* zero remainder by bytes */`
			`rep`
make an arch directory in libc, and move all machine dirs into it 1993-10-07 03:17:24 +03:00			`stosb`

			`popl %edi`
			`ret`