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Matthias Weisserd8834a12011-03-10 21:36:32 +00001/*
2 * linux/arch/arm/lib/memset.S
3 *
4 * Copyright (C) 1995-2000 Russell King
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 * ASM optimised string functions
11 */
12#include <asm/assembler.h>
13
14 .text
15 .align 5
16 .word 0
17
181: subs r2, r2, #4 @ 1 do we have enough
19 blt 5f @ 1 bytes to align with?
20 cmp r3, #2 @ 1
21 strltb r1, [r0], #1 @ 1
22 strleb r1, [r0], #1 @ 1
23 strb r1, [r0], #1 @ 1
24 add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
25/*
26 * The pointer is now aligned and the length is adjusted. Try doing the
27 * memset again.
28 */
29
30.globl memset
31memset:
32 ands r3, r0, #3 @ 1 unaligned?
33 bne 1b @ 1
34/*
35 * we know that the pointer in r0 is aligned to a word boundary.
36 */
37 orr r1, r1, r1, lsl #8
38 orr r1, r1, r1, lsl #16
39 mov r3, r1
40 cmp r2, #16
41 blt 4f
42
43#if ! CALGN(1)+0
44
45/*
46 * We need an extra register for this loop - save the return address and
47 * use the LR
48 */
49 str lr, [sp, #-4]!
50 mov ip, r1
51 mov lr, r1
52
532: subs r2, r2, #64
54 stmgeia r0!, {r1, r3, ip, lr} @ 64 bytes at a time.
55 stmgeia r0!, {r1, r3, ip, lr}
56 stmgeia r0!, {r1, r3, ip, lr}
57 stmgeia r0!, {r1, r3, ip, lr}
58 bgt 2b
59 ldmeqfd sp!, {pc} @ Now <64 bytes to go.
60/*
61 * No need to correct the count; we're only testing bits from now on
62 */
63 tst r2, #32
64 stmneia r0!, {r1, r3, ip, lr}
65 stmneia r0!, {r1, r3, ip, lr}
66 tst r2, #16
67 stmneia r0!, {r1, r3, ip, lr}
68 ldr lr, [sp], #4
69
70#else
71
72/*
73 * This version aligns the destination pointer in order to write
74 * whole cache lines at once.
75 */
76
77 stmfd sp!, {r4-r7, lr}
78 mov r4, r1
79 mov r5, r1
80 mov r6, r1
81 mov r7, r1
82 mov ip, r1
83 mov lr, r1
84
85 cmp r2, #96
86 tstgt r0, #31
87 ble 3f
88
89 and ip, r0, #31
90 rsb ip, ip, #32
91 sub r2, r2, ip
92 movs ip, ip, lsl #(32 - 4)
93 stmcsia r0!, {r4, r5, r6, r7}
94 stmmiia r0!, {r4, r5}
95 tst ip, #(1 << 30)
96 mov ip, r1
97 strne r1, [r0], #4
98
993: subs r2, r2, #64
100 stmgeia r0!, {r1, r3-r7, ip, lr}
101 stmgeia r0!, {r1, r3-r7, ip, lr}
102 bgt 3b
103 ldmeqfd sp!, {r4-r7, pc}
104
105 tst r2, #32
106 stmneia r0!, {r1, r3-r7, ip, lr}
107 tst r2, #16
108 stmneia r0!, {r4-r7}
109 ldmfd sp!, {r4-r7, lr}
110
111#endif
112
1134: tst r2, #8
114 stmneia r0!, {r1, r3}
115 tst r2, #4
116 strne r1, [r0], #4
117/*
118 * When we get here, we've got less than 4 bytes to zero. We
119 * may have an unaligned pointer as well.
120 */
1215: tst r2, #2
122 strneb r1, [r0], #1
123 strneb r1, [r0], #1
124 tst r2, #1
125 strneb r1, [r0], #1
126 mov pc, lr