[apple/libc.git] / i386 / string / bzero_scalar.s

/*
 * Copyright (c) 2003-2006 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. The rights granted to you under the License
 * may not be used to create, or enable the creation or redistribution of,
 * unlawful or unlicensed copies of an Apple operating system, or to
 * circumvent, violate, or enable the circumvention or violation of, any
 * terms of an Apple operating system software license agreement.
 * 
 * Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
 */
/*
 * Copyright (c) 1993 Winning Strategies, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *      This product includes software developed by Winning Strategies, Inc.
 * 4. The name of the author may not be used to endorse or promote products
 *    derived from this software withough specific prior written permission
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 */

#include <sys/appleapiopts.h>
#include <machine/cpu_capabilities.h>
#include <platfunc.h>

/*
 * bzero (void *b, size_t len)
 *      write len zero bytes to the string b.
 *
 * Written by:
 *      J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
 */

PLATFUNC_FUNCTION_START_GENERIC(bzero, scalar, 32, 4)
	pushl	%ebp			/* set up a frame for backtraces */
	movl	%esp,%ebp
	pushl   %edi
	pushl   %ebx
	movl    8(%ebp),%edi
	movl    12(%ebp),%ecx

	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    $0x0f,%ecx
	jbe     L1

	movl    %edi,%edx               /* compute misalignment */
	negl    %edx
	andl    $3,%edx
	movl    %ecx,%ebx
	subl    %edx,%ebx

	movl    %edx,%ecx               /* zero until word aligned */
	rep
	stosb

	movl    %ebx,%ecx               /* zero by words */
	shrl    $2,%ecx
	rep
	stosl

	movl    %ebx,%ecx
	andl    $3,%ecx                 /* zero remainder by bytes */
L1:     rep
	stosb

	popl    %ebx
	popl    %edi
	popl	%ebp
	ret

PLATFUNC_DESCRIPTOR(bzero,scalar,0,0)
Commit	Line	Data
1f2f436a A	1	/*
	2	* Copyright (c) 2003-2006 Apple Computer, Inc. All rights reserved.
	3	*
	4	* @APPLE_OSREFERENCE_LICENSE_HEADER_START@
	5	*
	6	* This file contains Original Code and/or Modifications of Original Code
	7	* as defined in and that are subject to the Apple Public Source License
	8	* Version 2.0 (the 'License'). You may not use this file except in
	9	* compliance with the License. The rights granted to you under the License
	10	* may not be used to create, or enable the creation or redistribution of,
	11	* unlawful or unlicensed copies of an Apple operating system, or to
	12	* circumvent, violate, or enable the circumvention or violation of, any
	13	* terms of an Apple operating system software license agreement.
	14	*
	15	* Please obtain a copy of the License at
	16	* http://www.opensource.apple.com/apsl/ and read it before using this file.
	17	*
	18	* The Original Code and all software distributed under the License are
	19	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
	20	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
	21	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
	22	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	23	* Please see the License for the specific language governing rights and
	24	* limitations under the License.
	25	*
	26	* @APPLE_OSREFERENCE_LICENSE_HEADER_END@
	27	*/
	28	/*
	29	* Copyright (c) 1993 Winning Strategies, Inc.
	30	* All rights reserved.
	31	*
	32	* Redistribution and use in source and binary forms, with or without
	33	* modification, are permitted provided that the following conditions
	34	* are met:
	35	* 1. Redistributions of source code must retain the above copyright
	36	* notice, this list of conditions and the following disclaimer.
	37	* 2. Redistributions in binary form must reproduce the above copyright
	38	* notice, this list of conditions and the following disclaimer in the
	39	* documentation and/or other materials provided with the distribution.
	40	* 3. All advertising materials mentioning features or use of this software
	41	* must display the following acknowledgement:
	42	* This product includes software developed by Winning Strategies, Inc.
	43	* 4. The name of the author may not be used to endorse or promote products
	44	* derived from this software withough specific prior written permission
	45	*
	46	* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
	47	* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
	48	* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
	49	* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
	50	* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
	51	* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
	52	* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
	53	* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
	54	* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
	55	* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
	56	*
	57	*/
	58
	59	#include <sys/appleapiopts.h>
	60	#include <machine/cpu_capabilities.h>
	61	#include <platfunc.h>
	62
	63	/*
	64	* bzero (void *b, size_t len)
65	* write len zero bytes to the string b.
66	*
67	* Written by:
68	* J.T. Conklin (jtc@wimsey.com), Winning Strategies, Inc.
69	*/
70
71	PLATFUNC_FUNCTION_START_GENERIC(bzero, scalar, 32, 4)
72	pushl %ebp /* set up a frame for backtraces */
73	movl %esp,%ebp
74	pushl %edi
75	pushl %ebx
76	movl 8(%ebp),%edi
77	movl 12(%ebp),%ecx
78
79	cld /* set fill direction forward */
80	xorl %eax,%eax /* set fill data to 0 */
81
82	/*
83	* if the string is too short, it's really not worth the overhead
84	* of aligning to word boundries, etc. So we jump to a plain
85	* unaligned set.
86	*/
87	cmpl $0x0f,%ecx
88	jbe L1
89
90	movl %edi,%edx /* compute misalignment */
91	negl %edx
92	andl $3,%edx
93	movl %ecx,%ebx
94	subl %edx,%ebx
95
96	movl %edx,%ecx /* zero until word aligned */
97	rep
98	stosb
99
100	movl %ebx,%ecx /* zero by words */
101	shrl $2,%ecx
102	rep
103	stosl
104
105	movl %ebx,%ecx
106	andl $3,%ecx /* zero remainder by bytes */
107	L1: rep
108	stosb
109
110	popl %ebx
111	popl %edi
112	popl %ebp
113	ret
114
115	PLATFUNC_DESCRIPTOR(bzero,scalar,0,0)