UbixOS  2.0
strncmp.S
Go to the documentation of this file.
1 /*-
2  * Copyright (c) 2002-2018 The UbixOS Project.
3  * All rights reserved.
4  *
5  * This was developed by Christopher W. Olsen for the UbixOS Project.
6  *
7  * Redistribution and use in source and binary forms, with or without modification, are permitted
8  * provided that the following conditions are met:
9  *
10  * 1) Redistributions of source code must retain the above copyright notice, this list of
11  * conditions, the following disclaimer and the list of authors.
12  * 2) Redistributions in binary form must reproduce the above copyright notice, this list of
13  * conditions, the following disclaimer and the list of authors in the documentation and/or
14  * other materials provided with the distribution.
15  * 3) Neither the name of the UbixOS Project nor the names of its contributors may be used to
16  * endorse or promote products derived from this software without specific prior written
17  * permission.
18  *
19  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
20  * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
21  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS
22  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA,
24  * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
26  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29  #include <i386/asmacros.h>
30 
31 ENTRY(strncmp)
32  pushl %ebx
33  movl 8(%esp),%eax
34  movl 12(%esp),%ecx
35  movl 16(%esp),%edx
36  testl %edx,%edx
37  jmp L2 /* Jump into the loop! */
38 
39  .align 2,0x90
40 L1: incl %eax
41  incl %ecx
42  decl %edx
43 L2: jz L4 /* strings are equal */
44  movb (%eax),%bl
45  testb %bl,%bl
46  jz L3
47  cmpb %bl,(%ecx)
48  jne L3
49  incl %eax
50  incl %ecx
51  decl %edx
52  jz L4
53  movb (%eax),%bl
54  testb %bl,%bl
55  jz L3
56  cmpb %bl,(%ecx)
57  jne L3
58 
59  incl %eax
60  incl %ecx
61  decl %edx
62  jz L4
63  movb (%eax),%bl
64  testb %bl,%bl
65  jz L3
66  cmpb %bl,(%ecx)
67  jne L3
68 
69  incl %eax
70  incl %ecx
71  decl %edx
72  jz L4
73  movb (%eax),%bl
74  testb %bl,%bl
75  jz L3
76  cmpb %bl,(%ecx)
77  jne L3
78 
79  incl %eax
80  incl %ecx
81  decl %edx
82  jz L4
83  movb (%eax),%bl
84  testb %bl,%bl
85  jz L3
86  cmpb %bl,(%ecx)
87  jne L3
88 
89  incl %eax
90  incl %ecx
91  decl %edx
92  jz L4
93  movb (%eax),%bl
94  testb %bl,%bl
95  jz L3
96  cmpb %bl,(%ecx)
97  jne L3
98 
99  incl %eax
100  incl %ecx
101  decl %edx
102  jz L4
103  movb (%eax),%bl
104  testb %bl,%bl
105  jz L3
106  cmpb %bl,(%ecx)
107  jne L3
108 
109  incl %eax
110  incl %ecx
111  decl %edx
112  jz L4
113  movb (%eax),%bl
114  testb %bl,%bl
115  jz L3
116  cmpb %bl,(%ecx)
117  je L1
118 
119  .align 2,0x90
120 L3: movzbl (%eax),%eax /* unsigned comparison */
121  movzbl (%ecx),%ecx
122  subl %ecx,%eax
123  popl %ebx
124  ret
125  .align 2,0x90
126 L4: xorl %eax,%eax
127  popl %ebx
128  ret
129 END(strncmp)