Commit | Line | Data |
---|---|---|
249ac17e CZ |
1 | /* |
2 | * arch/xtensa/lib/strnlen_user.S | |
3 | * | |
4 | * This file is subject to the terms and conditions of the GNU General | |
5 | * Public License. See the file "COPYING" in the main directory of | |
6 | * this archive for more details. | |
7 | * | |
8 | * Returns strnlen, including trailing zero terminator. | |
9 | * Zero indicates error. | |
10 | * | |
11 | * Copyright (C) 2002 Tensilica Inc. | |
12 | */ | |
13 | ||
173d6681 | 14 | #include <asm/variant/core.h> |
249ac17e CZ |
15 | |
16 | /* Load or store instructions that may cause exceptions use the EX macro. */ | |
17 | ||
18 | #define EX(insn,reg1,reg2,offset,handler) \ | |
19 | 9: insn reg1, reg2, offset; \ | |
20 | .section __ex_table, "a"; \ | |
21 | .word 9b, handler; \ | |
22 | .previous | |
23 | ||
24 | /* | |
25 | * size_t __strnlen_user(const char *s, size_t len) | |
26 | */ | |
a0bb46ba CZ |
27 | |
28 | #ifdef __XTENSA_EB__ | |
29 | # define MASK0 0xff000000 | |
30 | # define MASK1 0x00ff0000 | |
31 | # define MASK2 0x0000ff00 | |
32 | # define MASK3 0x000000ff | |
33 | #else | |
34 | # define MASK0 0x000000ff | |
35 | # define MASK1 0x0000ff00 | |
36 | # define MASK2 0x00ff0000 | |
37 | # define MASK3 0xff000000 | |
38 | #endif | |
249ac17e CZ |
39 | |
40 | # Register use: | |
41 | # a2/ src | |
42 | # a3/ len | |
43 | # a4/ tmp | |
44 | # a5/ mask0 | |
45 | # a6/ mask1 | |
46 | # a7/ mask2 | |
47 | # a8/ mask3 | |
48 | # a9/ tmp | |
49 | # a10/ tmp | |
50 | ||
a0bb46ba | 51 | .text |
249ac17e CZ |
52 | .align 4 |
53 | .global __strnlen_user | |
54 | .type __strnlen_user,@function | |
55 | __strnlen_user: | |
56 | entry sp, 16 # minimal stack frame | |
57 | # a2/ s, a3/ len | |
58 | addi a4, a2, -4 # because we overincrement at the end; | |
59 | # we compensate with load offsets of 4 | |
a0bb46ba CZ |
60 | movi a5, MASK0 # mask for byte 0 |
61 | movi a6, MASK1 # mask for byte 1 | |
62 | movi a7, MASK2 # mask for byte 2 | |
63 | movi a8, MASK3 # mask for byte 3 | |
249ac17e CZ |
64 | bbsi.l a2, 0, .L1mod2 # if only 8-bit aligned |
65 | bbsi.l a2, 1, .L2mod4 # if only 16-bit aligned | |
66 | ||
67 | /* | |
68 | * String is word-aligned. | |
69 | */ | |
70 | .Laligned: | |
71 | srli a10, a3, 2 # number of loop iterations with 4B per loop | |
72 | #if XCHAL_HAVE_LOOPS | |
73 | loopnez a10, .Ldone | |
74 | #else | |
75 | beqz a10, .Ldone | |
76 | slli a10, a10, 2 | |
77 | add a10, a10, a4 # a10 = end of last 4B chunk | |
78 | #endif /* XCHAL_HAVE_LOOPS */ | |
79 | .Loop: | |
80 | EX(l32i, a9, a4, 4, lenfixup) # get next word of string | |
81 | addi a4, a4, 4 # advance string pointer | |
82 | bnone a9, a5, .Lz0 # if byte 0 is zero | |
83 | bnone a9, a6, .Lz1 # if byte 1 is zero | |
84 | bnone a9, a7, .Lz2 # if byte 2 is zero | |
85 | bnone a9, a8, .Lz3 # if byte 3 is zero | |
86 | #if !XCHAL_HAVE_LOOPS | |
87 | blt a4, a10, .Loop | |
88 | #endif | |
89 | ||
90 | .Ldone: | |
91 | EX(l32i, a9, a4, 4, lenfixup) # load 4 bytes for remaining checks | |
92 | ||
93 | bbci.l a3, 1, .L100 | |
94 | # check two more bytes (bytes 0, 1 of word) | |
95 | addi a4, a4, 2 # advance string pointer | |
96 | bnone a9, a5, .Lz0 # if byte 0 is zero | |
97 | bnone a9, a6, .Lz1 # if byte 1 is zero | |
98 | .L100: | |
99 | bbci.l a3, 0, .L101 | |
100 | # check one more byte (byte 2 of word) | |
101 | # Actually, we don't need to check. Zero or nonzero, we'll add one. | |
102 | # Do not add an extra one for the NULL terminator since we have | |
103 | # exhausted the original len parameter. | |
104 | addi a4, a4, 1 # advance string pointer | |
105 | .L101: | |
106 | sub a2, a4, a2 # compute length | |
107 | retw | |
108 | ||
109 | # NOTE that in several places below, we point to the byte just after | |
110 | # the zero byte in order to include the NULL terminator in the count. | |
111 | ||
112 | .Lz3: # byte 3 is zero | |
113 | addi a4, a4, 3 # point to zero byte | |
114 | .Lz0: # byte 0 is zero | |
115 | addi a4, a4, 1 # point just beyond zero byte | |
116 | sub a2, a4, a2 # subtract to get length | |
117 | retw | |
118 | .Lz1: # byte 1 is zero | |
119 | addi a4, a4, 1+1 # point just beyond zero byte | |
120 | sub a2, a4, a2 # subtract to get length | |
121 | retw | |
122 | .Lz2: # byte 2 is zero | |
123 | addi a4, a4, 2+1 # point just beyond zero byte | |
124 | sub a2, a4, a2 # subtract to get length | |
125 | retw | |
126 | ||
127 | .L1mod2: # address is odd | |
128 | EX(l8ui, a9, a4, 4, lenfixup) # get byte 0 | |
129 | addi a4, a4, 1 # advance string pointer | |
130 | beqz a9, .Lz3 # if byte 0 is zero | |
131 | bbci.l a4, 1, .Laligned # if string pointer is now word-aligned | |
132 | ||
133 | .L2mod4: # address is 2 mod 4 | |
134 | addi a4, a4, 2 # advance ptr for aligned access | |
135 | EX(l32i, a9, a4, 0, lenfixup) # get word with first two bytes of string | |
136 | bnone a9, a7, .Lz2 # if byte 2 (of word, not string) is zero | |
137 | bany a9, a8, .Laligned # if byte 3 (of word, not string) is nonzero | |
138 | # byte 3 is zero | |
139 | addi a4, a4, 3+1 # point just beyond zero byte | |
140 | sub a2, a4, a2 # subtract to get length | |
141 | retw | |
142 | ||
143 | .section .fixup, "ax" | |
144 | .align 4 | |
145 | lenfixup: | |
146 | movi a2, 0 | |
147 | retw | |
148 |