xref: /illumos-gate/usr/src/lib/libc/i386/gen/strrchr.S (revision 55fea89dcaa64928bed4327112404dcb3e07b79f)
1*5d9d9091SRichard Lowe/*
2*5d9d9091SRichard Lowe * CDDL HEADER START
3*5d9d9091SRichard Lowe *
4*5d9d9091SRichard Lowe * The contents of this file are subject to the terms of the
5*5d9d9091SRichard Lowe * Common Development and Distribution License (the "License").
6*5d9d9091SRichard Lowe * You may not use this file except in compliance with the License.
7*5d9d9091SRichard Lowe *
8*5d9d9091SRichard Lowe * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9*5d9d9091SRichard Lowe * or http://www.opensolaris.org/os/licensing.
10*5d9d9091SRichard Lowe * See the License for the specific language governing permissions
11*5d9d9091SRichard Lowe * and limitations under the License.
12*5d9d9091SRichard Lowe *
13*5d9d9091SRichard Lowe * When distributing Covered Code, include this CDDL HEADER in each
14*5d9d9091SRichard Lowe * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15*5d9d9091SRichard Lowe * If applicable, add the following below this CDDL HEADER, with the
16*5d9d9091SRichard Lowe * fields enclosed by brackets "[]" replaced with your own identifying
17*5d9d9091SRichard Lowe * information: Portions Copyright [yyyy] [name of copyright owner]
18*5d9d9091SRichard Lowe *
19*5d9d9091SRichard Lowe * CDDL HEADER END
20*5d9d9091SRichard Lowe */
21*5d9d9091SRichard Lowe/*
22*5d9d9091SRichard Lowe * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
23*5d9d9091SRichard Lowe * Use is subject to license terms.
24*5d9d9091SRichard Lowe */
25*5d9d9091SRichard Lowe
26*5d9d9091SRichard Lowe	.file	"strrchr.s"
27*5d9d9091SRichard Lowe
28*5d9d9091SRichard Lowe/
29*5d9d9091SRichard Lowe/ strrchr(sp, c)
30*5d9d9091SRichard Lowe/
31*5d9d9091SRichard Lowe/ Returns the pointer in sp at which the character c last
32*5d9d9091SRichard Lowe/ appears; NULL if no found
33*5d9d9091SRichard Lowe/
34*5d9d9091SRichard Lowe/ Fast assembly language version of the following C-program strrchr
35*5d9d9091SRichard Lowe/ which represents the `standard' for the C-library.
36*5d9d9091SRichard Lowe/
37*5d9d9091SRichard Lowe/	char *
38*5d9d9091SRichard Lowe/	strrchr(const char *sp, int c)
39*5d9d9091SRichard Lowe/	{
40*5d9d9091SRichard Lowe/		char	*r = NULL;
41*5d9d9091SRichard Lowe/
42*5d9d9091SRichard Lowe/		do {
43*5d9d9091SRichard Lowe/			if (*sp == (char)c)
44*5d9d9091SRichard Lowe/				r = (char *)sp;
45*5d9d9091SRichard Lowe/		} while (*sp++);
46*5d9d9091SRichard Lowe/
47*5d9d9091SRichard Lowe/		return (r);
48*5d9d9091SRichard Lowe/	}
49*5d9d9091SRichard Lowe/
50*5d9d9091SRichard Lowe
51*5d9d9091SRichard Lowe#include "SYS.h"
52*5d9d9091SRichard Lowe
53*5d9d9091SRichard Lowe	ENTRY(strrchr)
54*5d9d9091SRichard Lowe	pushl	%edi		/ save register variable
55*5d9d9091SRichard Lowe	movl	8(%esp), %eax	/ %eax = string address
56*5d9d9091SRichard Lowe	movb	12(%esp), %cl	/ %cl = char sought
57*5d9d9091SRichard Lowe	movl	$0, %edi	/ %edi = NULL (current occurrence)
58*5d9d9091SRichard Lowe
59*5d9d9091SRichard Lowe	testl	$3, %eax	/ if %eax not word aligned
60*5d9d9091SRichard Lowe	jnz	.L1		/ goto .L1
61*5d9d9091SRichard Lowe	.align	4
62*5d9d9091SRichard Lowe.L3:
63*5d9d9091SRichard Lowe	movl	(%eax), %edx	/ move 1 word from (%eax) to %edx
64*5d9d9091SRichard Lowe	cmpb	%cl, %dl	/ if the fist byte is not %cl
65*5d9d9091SRichard Lowe	jne	.L4		/ goto .L4
66*5d9d9091SRichard Lowe	movl	%eax, %edi	/ save this address to %edi
67*5d9d9091SRichard Lowe.L4:
68*5d9d9091SRichard Lowe	cmpb	$0, %dl		/ if a null termination
69*5d9d9091SRichard Lowe	je	.L8		/ goto .L8
70*5d9d9091SRichard Lowe
71*5d9d9091SRichard Lowe	cmpb	%cl, %dh	/ if the second byte is not %cl
72*5d9d9091SRichard Lowe	jne	.L5		/ goto .L5
73*5d9d9091SRichard Lowe	leal	1(%eax), %edi	/ save this address to %edi
74*5d9d9091SRichard Lowe.L5:
75*5d9d9091SRichard Lowe	cmpb	$0, %dh		/ if a null termination
76*5d9d9091SRichard Lowe	je	.L8		/ goto .L8
77*5d9d9091SRichard Lowe
78*5d9d9091SRichard Lowe	shrl	$16, %edx	/ right shift 16-bit
79*5d9d9091SRichard Lowe	cmpb	%cl, %dl	/ if the third byte is not %cl
80*5d9d9091SRichard Lowe	jne	.L6		/ goto .L6
81*5d9d9091SRichard Lowe	leal	2(%eax), %edi	/ save this address to %edi
82*5d9d9091SRichard Lowe.L6:
83*5d9d9091SRichard Lowe	cmpb	$0, %dl		/ if a null termination
84*5d9d9091SRichard Lowe	je	.L8		/ goto .L8
85*5d9d9091SRichard Lowe
86*5d9d9091SRichard Lowe	cmpb	%cl, %dh	/ if the fourth byte is not %cl
87*5d9d9091SRichard Lowe	jne	.L7		/ goto .L7
88*5d9d9091SRichard Lowe	leal	3(%eax), %edi	/ save this address to %edi
89*5d9d9091SRichard Lowe.L7:
90*5d9d9091SRichard Lowe	cmpb	$0, %dh		/ if a null termination
91*5d9d9091SRichard Lowe	je	.L8		/ goto .L8
92*5d9d9091SRichard Lowe
93*5d9d9091SRichard Lowe	addl	$4, %eax	/ next word
94*5d9d9091SRichard Lowe	jmp	.L3		/ goto .L3
95*5d9d9091SRichard Lowe	.align	4
96*5d9d9091SRichard Lowe.L1:
97*5d9d9091SRichard Lowe	movb	(%eax), %dl	/ move 1 byte from (%eax) to %dl
98*5d9d9091SRichard Lowe	cmpb	%cl, %dl	/ if %dl is not %cl
99*5d9d9091SRichard Lowe	jne	.L2		/ goto .L2
100*5d9d9091SRichard Lowe	movl	%eax, %edi	/ save this address to %edi
101*5d9d9091SRichard Lowe.L2:
102*5d9d9091SRichard Lowe	cmpb	$0, %dl		/ if a null termination
103*5d9d9091SRichard Lowe	je	.L8		/ goto .L8
104*5d9d9091SRichard Lowe
105*5d9d9091SRichard Lowe	incl	%eax		/ next byte
106*5d9d9091SRichard Lowe	testl	$3, %eax	/ if %eax not word aligned
107*5d9d9091SRichard Lowe	jnz	.L1		/ goto .L1
108*5d9d9091SRichard Lowe	jmp	.L3		/ goto .L3 (word aligned)
109*5d9d9091SRichard Lowe	.align	4
110*5d9d9091SRichard Lowe.L8:
111*5d9d9091SRichard Lowe	movl	%edi, %eax	/ %edi points to the last occurrence or NULL
112*5d9d9091SRichard Lowe	popl	%edi		/ restore register variable
113*5d9d9091SRichard Lowe	ret
114*5d9d9091SRichard Lowe	SET_SIZE(strrchr)
115