/*

 * 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 2005 Sun Microsystems, Inc.  All rights reserved.

 * Use is subject to license terms.

 */

#include "SYS.h"

	ENTRY(strchr)

	mov 4(%esp), %ecx		/ src string here

	mov 8(%esp), %edx		/ character to find

	mov %ecx, %eax			/ save src

	and $3, %ecx			/ check if src is aligned

	jz prepword			/ search wordwise if it is

	cmpb %dl, (%eax)		/ src == char?

	jz done

	cmpb $0, (%eax)			/ src == 0?

	jz not_found

	add $1, %eax			/ increment src

	cmp $3, %ecx			/ check alignment

	jz prepword

	cmpb %dl, (%eax)		/ src byte contains char?

	jz done

	cmpb $0, (%eax)			/ src byte == 0?

	jz not_found

	add $1, %eax			/ increment src ptr

	cmp $2, %ecx			/ check alignment

	jz prepword

	cmpb %dl, (%eax) 		/ check this byte

	jz done

	cmpb $0, (%eax)			/ is byte zero?

	jz not_found

	add $1, %eax			/ increment src ptr

prepword:

	push %ebx			/ save regs per calling convention

	push %esi

	and $0xff, %edx			/ only want 1st byte

	mov %edx, %ebx			/ copy character across all bytes in wd

	shl $8, %edx

	or %ebx, %edx

	mov %edx, %ebx

	shl $16, %edx

	or %ebx, %edx

	.align 16			/ align loop for max performance

searchchar:

	mov (%eax), %esi		/ load src word

	add $4, %eax			/ increment src by four

	mov %esi, %ebx			/ copy word

	lea -0x01010101(%esi), %ecx	/ (word - 0x01010101)

	xor %edx, %ebx			/ tmpword = word ^ char	

	not %esi			/ ~word

	and $0x80808080, %esi		/ ~word & 0x80808080

	and %ecx, %esi			/ (wd - 0x01010101) & ~wd & 0x80808080

	jnz has_zero_byte

	lea -0x01010101(%ebx), %ecx	/ repeat with tmpword

	not %ebx

	and $0x80808080, %ebx

	and %ecx, %ebx

	jz searchchar			/ repeat if char not found

found_char:

	add $0x01010101, %ecx		/ restore tmpword

	pop %esi			/ restore esi ebx as per calling cvntn

	pop %ebx

	test $0x000000ff, %ecx		/ look for character's position in word

	jz done0

	test $0x0000ff00, %ecx

	jz done1

	test $0x00ff0000, %ecx

	jz done2

done3:

	sub $1, %eax

	ret

done2:

	sub $2, %eax

	ret

done1:

	sub $3, %eax

	ret

done0:

	sub $4, %eax

	ret

has_zero_byte:

	add $0x01010101, %ecx		/ restore registers here

	pop %esi

	pop %ebx

	cmpb %dl, %cl			/ check for character

	je done0

	testb %cl, %cl			/ check for null byte

	jz not_found

	cmpb %dh, %ch			/ continue checking for char, null

	je done1

	testb %ch, %ch

	jz not_found

	shr $16, %ecx			/ put bytes 2,3 into 8-but registers

	cmpb %dl, %cl

	je done2

	testb %cl, %cl

	jz not_found

	cmpb %dh, %ch			/ repeat checking last 2 bytes

	je done3

	testb %ch, %ch

	jz not_found

	sub $1, %eax			/ correct for last loop iteration

done:

	ret

not_found:

	xor %eax, %eax

	ret

	SET_SIZE(strchr)