1 /*
2 * arch/xtensa/lib/memset.S
3 *
4 * ANSI C standard library function memset
5 * (Well, almost. .fixup code might return z
6 *
7 * This file is subject to the terms and cond
8 * Public License. See the file "COPYING" in
9 * this archive for more details.
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 * void *memset(void *dst, int c, size_t lengt
20 *
21 * The algorithm is as follows:
22 * Create a word with c in all byte position
23 * If the destination is aligned,
24 * do 16B chucks with a loop, and then fin
25 * 8B, 4B, 2B, and 1B stores conditional o
26 * If destination is unaligned, align it by
27 * setting 1B and 2B and then go to aligne
28 * This code tries to use fall-through branc
29 * case of an aligned destination (except
30 * the alignment labels).
31 */
32
33 .text
34 ENTRY(__memset)
35 WEAK(memset)
36
37 abi_entry_default
38 # a2/ dst, a3/ c, a4/ length
39 extui a3, a3, 0, 8 # mask to just
40 slli a7, a3, 8 # duplicate ch
41 or a3, a3, a7 # ...
42 slli a7, a3, 16 # ...
43 or a3, a3, a7 # ...
44 mov a5, a2 # copy dst so
45 movi a6, 3 # for alignmen
46 bany a2, a6, .Ldstunaligned # if ds
47 .L0: # return here from .Ldstunaligned when
48 srli a7, a4, 4 # number of lo
49 # per iteratio
50 bnez a4, .Laligned
51 abi_ret_default
52
53 /*
54 * Destination is word-aligned.
55 */
56 # set 16 bytes per iteration for word-
57 .align 4 # 1 mod 4 alig
58 .byte 0 # (0 mod 4 ali
59 .Laligned:
60 #if XCHAL_HAVE_LOOPS
61 loopnez a7, .Loop1done
62 #else /* !XCHAL_HAVE_LOOPS */
63 beqz a7, .Loop1done
64 slli a6, a7, 4
65 add a6, a6, a5 # a6 = end of
66 #endif /* !XCHAL_HAVE_LOOPS */
67 .Loop1:
68 EX(10f) s32i a3, a5, 0
69 EX(10f) s32i a3, a5, 4
70 EX(10f) s32i a3, a5, 8
71 EX(10f) s32i a3, a5, 12
72 addi a5, a5, 16
73 #if !XCHAL_HAVE_LOOPS
74 blt a5, a6, .Loop1
75 #endif /* !XCHAL_HAVE_LOOPS */
76 .Loop1done:
77 bbci.l a4, 3, .L2
78 # set 8 bytes
79 EX(10f) s32i a3, a5, 0
80 EX(10f) s32i a3, a5, 4
81 addi a5, a5, 8
82 .L2:
83 bbci.l a4, 2, .L3
84 # set 4 bytes
85 EX(10f) s32i a3, a5, 0
86 addi a5, a5, 4
87 .L3:
88 bbci.l a4, 1, .L4
89 # set 2 bytes
90 EX(10f) s16i a3, a5, 0
91 addi a5, a5, 2
92 .L4:
93 bbci.l a4, 0, .L5
94 # set 1 byte
95 EX(10f) s8i a3, a5, 0
96 .L5:
97 .Lret1:
98 abi_ret_default
99
100 /*
101 * Destination is unaligned
102 */
103
104 .Ldstunaligned:
105 bltui a4, 8, .Lbyteset # do s
106 bbci.l a5, 0, .L20 # bran
107 # dst is only byte aligned
108 # set 1 byte
109 EX(10f) s8i a3, a5, 0
110 addi a5, a5, 1
111 addi a4, a4, -1
112 # now retest if dst aligned
113 bbci.l a5, 1, .L0 # if now align
114 .L20:
115 # dst half-aligned
116 # set 2 bytes
117 EX(10f) s16i a3, a5, 0
118 addi a5, a5, 2
119 addi a4, a4, -2
120 j .L0 # dst is now a
121
122 /*
123 * Byte by byte set
124 */
125 .align 4
126 .byte 0 # 1 mod 4 alig
127 # (0 mod 4 ali
128 .Lbyteset:
129 #if XCHAL_HAVE_LOOPS
130 loopnez a4, .Lbytesetdone
131 #else /* !XCHAL_HAVE_LOOPS */
132 beqz a4, .Lbytesetdone
133 add a6, a5, a4 # a6 = ending
134 #endif /* !XCHAL_HAVE_LOOPS */
135 .Lbyteloop:
136 EX(10f) s8i a3, a5, 0
137 addi a5, a5, 1
138 #if !XCHAL_HAVE_LOOPS
139 blt a5, a6, .Lbyteloop
140 #endif /* !XCHAL_HAVE_LOOPS */
141 .Lbytesetdone:
142 abi_ret_default
143
144 ENDPROC(__memset)
145 EXPORT_SYMBOL(__memset)
146 EXPORT_SYMBOL(memset)
147
148 .section .fixup, "ax"
149 .align 4
150
151 /* We return zero if a failure occurred. */
152
153 10:
154 movi a2, 0
155 abi_ret_default
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