/*

 * CDDL HEADER START

 *

 * The contents of this file are subject to the terms of the

 *

 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE

 * or http://www.opensolaris.org/os/licensing.

 * See the License for the specific language governing permissions

 * and limitations under the License.

 *

 * When distributing Covered Code, include this CDDL HEADER in each

 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.

 * If applicable, add the following below this CDDL HEADER, with the

 * fields enclosed by brackets "[]" replaced with your own identifying

 * information: Portions Copyright [yyyy] [name of copyright owner]

 *

 * CDDL HEADER END

 */

/*

 * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

/

/ memchr(sptr, c1, n)

/

/ Returns the pointer in sptr at which the character c1 appears; 

/ or NULL if not found in chars; doesn't stop at \0.

/

/ Fast assembly language version of the following C-program memchr

/ which represents the `standard' for the C-library.

/ 

/	void *

/	memchr(const void *sptr, int c1, size_t n)

/	{

/		if (n != 0) {

/			unsigned char	c = (unsigned char)c1; 

/			const unsigned char	*sp = sptr; 

/

/			do {

/				if (*sp++ == c)

/					return ((void *)--sp); 

/			} while (--n != 0); 

/		}

/		return (NULL); 

/	}

/

#include "SYS.h"

	.globl	memchr

	.align	4

	ENTRY(memchr)

	pushl	%edi		/ save register variable

	movl	8(%esp), %eax	/ %eax = string address

	movl	12(%esp), %ecx	/ %cl = byte that is sought

	movl	16(%esp), %edi	/ %edi = number of bytes

	cmpl	$4, %edi	/ if number of bytes < 4

	jb	.L1		/ goto .L1

	testl	$3, %eax	/ if %eax not word aligned

	jnz	.L2		/ goto .L2

	.align	4

.L3:

	movl	(%eax), %edx	/ move 1 word from (%eax) to %edx

	cmpb	%dl, %cl	/ if the first byte is %cl

	je	.L4		/ goto .L4 (found)

	cmpb	%dh, %cl	/ if the second byte is %cl

	je	.L5		/ goto .L5 (found)

	shrl	$16, %edx	/ right shift 16-bit

	cmpb	%dl, %cl	/ if the third byte is %cl

	je	.L6		/ goto .L6 (found)

	cmpb	%dh, %cl	/ if the fourth is %cl

	je	.L7		/ goto .L7 (found)

	subl	$4, %edi	/ decrement number of bytes by 4

	addl	$4, %eax	/ next word

	cmpl	$4, %edi	/ if number of bytes >= 4

	jae	.L3		/ goto .L3

.L1:

	cmpl	$0, %edi	/ if number of bytes == 0

	jz	.L8		/ goto .L8 (not found)

	cmpb	(%eax), %cl	/ if a byte in (%eax) is %cl

	je	.L4		/ goto .L4 (found)

	decl	%edi		/ decrement number of bytes by 1

	incl	%eax		/ next byte

	jmp	.L1		/ goto .L1

	.align	4

.L8:	

	xorl	%eax, %eax	/ not found

	popl	%edi		/ restore register

	ret			/ return (0)

	.align	4

.L2:

	cmpl	$0, %edi	/ if number of bytes == 0

	jz	.L8		/ goto .L8 (not found)

	cmpb	(%eax), %cl	/ if a byte in (%eax) is %cl

	je	.L4		/ goto .L4 (found)

	incl	%eax		/ next byte

	decl	%edi		/ decrement number of bytes by 1

	testl	$3, %eax	/ if %eax not word aligned

	jnz	.L2		/ goto .L2

	cmpl	$4, %edi	/ if number of bytes >= 4

	jae	.L3		/ goto .L3 (word aligned)

	jmp	.L1		/ goto .L1

	.align	4

.L7:

	/ found at the fourth byte	

	incl	%eax

.L6:

	/ found at the third byte

	incl	%eax

.L5:

	/ found at the second byte	

	incl	%eax

.L4:

	/ found at the first byte	

	popl	%edi		/ restore register variable

	ret			 

	SET_SIZE(memchr)