1 /*
2 * arch/xtensa/lib/strnlen_user.S
3 *
4 * This file is subject to the terms and cond
5 * Public License. See the file "COPYING" in
6 * this archive for more details.
7 *
8 * Returns strnlen, including trailing zero t
9 * Zero indicates error.
10 *
11 * Copyright (C) 2002 Tensilica Inc.
12 */
13
14 #include <linux/linkage.h>
15 #include <asm/asmmacro.h>
16 #include <asm/core.h>
17
18 /*
19 * size_t __strnlen_user(const char *s, size_t
20 */
21
22 #ifdef __XTENSA_EB__
23 # define MASK0 0xff000000
24 # define MASK1 0x00ff0000
25 # define MASK2 0x0000ff00
26 # define MASK3 0x000000ff
27 #else
28 # define MASK0 0x000000ff
29 # define MASK1 0x0000ff00
30 # define MASK2 0x00ff0000
31 # define MASK3 0xff000000
32 #endif
33
34 # Register use:
35 # a2/ src
36 # a3/ len
37 # a4/ tmp
38 # a5/ mask0
39 # a6/ mask1
40 # a7/ mask2
41 # a8/ mask3
42 # a9/ tmp
43 # a10/ tmp
44
45 .text
46 ENTRY(__strnlen_user)
47
48 abi_entry_default
49 # a2/ s, a3/ len
50 addi a4, a2, -4 # because we o
51 # we compensat
52 movi a5, MASK0 # mask for byt
53 movi a6, MASK1 # mask for byt
54 movi a7, MASK2 # mask for byt
55 movi a8, MASK3 # mask for byt
56 bbsi.l a2, 0, .L1mod2 # if only 8-b
57 bbsi.l a2, 1, .L2mod4 # if only 16-b
58
59 /*
60 * String is word-aligned.
61 */
62 .Laligned:
63 srli a10, a3, 2 # number of lo
64 #if XCHAL_HAVE_LOOPS
65 loopnez a10, .Ldone
66 #else
67 beqz a10, .Ldone
68 slli a10, a10, 2
69 add a10, a10, a4 # a10 = end of
70 #endif /* XCHAL_HAVE_LOOPS */
71 .Loop:
72 EX(10f) l32i a9, a4, 4 # get
73 addi a4, a4, 4 # adva
74 bnone a9, a5, .Lz0 # if b
75 bnone a9, a6, .Lz1 # if b
76 bnone a9, a7, .Lz2 # if b
77 bnone a9, a8, .Lz3 # if b
78 #if !XCHAL_HAVE_LOOPS
79 blt a4, a10, .Loop
80 #endif
81
82 .Ldone:
83 EX(10f) l32i a9, a4, 4 # load 4 bytes
84
85 bbci.l a3, 1, .L100
86 # check two more bytes (bytes 0, 1 of
87 addi a4, a4, 2 # advance stri
88 bnone a9, a5, .Lz0 # if byte 0 is
89 bnone a9, a6, .Lz1 # if byte 1 is
90 .L100:
91 bbci.l a3, 0, .L101
92 # check one more byte (byte 2 of word)
93 # Actually, we don't need to check. Z
94 # Do not add an extra one for the NULL
95 # exhausted the original len paramete
96 addi a4, a4, 1 # advance stri
97 .L101:
98 sub a2, a4, a2 # compute leng
99 abi_ret_default
100
101 # NOTE that in several places below, we point
102 # the zero byte in order to include the NULL t
103
104 .Lz3: # byte 3 is zero
105 addi a4, a4, 3 # point to zer
106 .Lz0: # byte 0 is zero
107 addi a4, a4, 1 # point just b
108 sub a2, a4, a2 # subtract to
109 abi_ret_default
110 .Lz1: # byte 1 is zero
111 addi a4, a4, 1+1 # point just b
112 sub a2, a4, a2 # subtract to
113 abi_ret_default
114 .Lz2: # byte 2 is zero
115 addi a4, a4, 2+1 # point just b
116 sub a2, a4, a2 # subtract to
117 abi_ret_default
118
119 .L1mod2: # address is odd
120 EX(10f) l8ui a9, a4, 4 # get
121 addi a4, a4, 1 # adva
122 beqz a9, .Lz3 # if b
123 bbci.l a4, 1, .Laligned # if s
124
125 .L2mod4: # address is 2 mod 4
126 addi a4, a4, 2 # advance ptr
127 EX(10f) l32i a9, a4, 0 # get word wit
128 bnone a9, a7, .Lz2 # if byte 2 (o
129 bany a9, a8, .Laligned # if byte 3
130 # byte 3 is zero
131 addi a4, a4, 3+1 # point just b
132 sub a2, a4, a2 # subtract to
133 abi_ret_default
134
135 ENDPROC(__strnlen_user)
136 EXPORT_SYMBOL(__strnlen_user)
137
138 .section .fixup, "ax"
139 .align 4
140 10:
141 movi a2, 0
142 abi_ret_default
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.