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      1 /*
      2  * CDDL HEADER START
      3  *
      4  * The contents of this file are subject to the terms of the
      5  * Common Development and Distribution License (the "License").
      6  * You may not use this file except in compliance with the License.
      7  *
      8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
      9  * or http://www.opensolaris.org/os/licensing.
     10  * See the License for the specific language governing permissions
     11  * and limitations under the License.
     12  *
     13  * When distributing Covered Code, include this CDDL HEADER in each
     14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
     15  * If applicable, add the following below this CDDL HEADER, with the
     16  * fields enclosed by brackets "[]" replaced with your own identifying
     17  * information: Portions Copyright [yyyy] [name of copyright owner]
     18  *
     19  * CDDL HEADER END
     20  */
     21 /*
     22  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
     23  * Use is subject to license terms.
     24  */
     25 
     26 	.file	"strrchr.s"
     27 
     28 /
     29 / strrchr(sp, c)
     30 /
     31 / Returns the pointer in sp at which the character c last
     32 / appears; NULL if no found
     33 /
     34 / Fast assembly language version of the following C-program strrchr
     35 / which represents the `standard' for the C-library.
     36 /
     37 /	char *
     38 /	strrchr(const char *sp, int c)
     39 /	{
     40 /		char	*r = NULL;
     41 /
     42 /		do {
     43 /			if (*sp == (char)c)
     44 /				r = (char *)sp;
     45 /		} while (*sp++);
     46 /
     47 /		return (r);
     48 /	}
     49 /
     50 
     51 #include "SYS.h"
     52 
     53 	ENTRY(strrchr)		/* (char *s, int c) */
     54 	movl	$0, %eax	/ %rax = NULL (current occurrence)
     55 	movl	%esi, %ecx	/ %cl == char to search for
     56 	testq	$3, %rdi	/ if %rdi not word aligned
     57 	jnz	.L1		/ goto .L1
     58 	.align	4
     59 .L3:
     60 	movl	(%rdi), %edx	/ move 1 word from (%rdi) to %edx
     61 	cmpb	%cl, %dl	/ if the fist byte is not %cl
     62 	jne	.L4		/ goto .L4
     63 	movq	%rdi, %rax	/ save this address to %rax
     64 .L4:
     65 	cmpb	$0, %dl		/ if a null termination
     66 	je	.L8		/ goto .L8
     67 
     68 	cmpb	%cl, %dh	/ if the second byte is not %cl
     69 	jne	.L5		/ goto .L5
     70 	leaq	1(%rdi), %rax	/ save this address to %rax
     71 .L5:
     72 	cmpb	$0, %dh		/ if a null termination
     73 	je	.L8		/ goto .L8
     74 
     75 	shrl	$16, %edx	/ right shift 16-bit
     76 	cmpb	%cl, %dl	/ if the third byte is not %cl
     77 	jne	.L6		/ goto .L6
     78 	leaq	2(%rdi), %rax	/ save this address to %rax
     79 .L6:
     80 	cmpb	$0, %dl		/ if a null termination
     81 	je	.L8		/ goto .L8
     82 
     83 	cmpb	%cl, %dh	/ if the fourth byte is not %cl
     84 	jne	.L7		/ goto .L7
     85 	leaq	3(%rdi), %rax	/ save this address to %rax
     86 .L7:
     87 	cmpb	$0, %dh		/ if a null termination
     88 	je	.L8		/ goto .L8
     89 
     90 	addq	$4, %rdi	/ next word
     91 	jmp	.L3		/ goto .L3
     92 	.align	4
     93 .L1:
     94 	movb	(%rdi), %dl	/ move 1 byte from (%rdi) to %dl
     95 	cmpb	%cl, %dl	/ if %dl is not %cl
     96 	jne	.L2		/ goto .L2
     97 	movq	%rdi, %rax	/ save this address to %rax
     98 .L2:
     99 	cmpb	$0, %dl		/ if a null termination
    100 	je	.L8		/ goto .L8
    101 
    102 	incq	%rdi		/ next byte
    103 	testq	$3, %rdi	/ if %rdi not word aligned
    104 	jnz	.L1		/ goto .L1
    105 	jmp	.L3		/ goto .L3 (word aligned)
    106 	.align	4
    107 .L8:
    108 	ret			/ %rax points to the last occurrence or NULL
    109 	SET_SIZE(strrchr)
    110