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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 <linux/linkage.h>
13#include <asm/assembler.h>
14
15 .text
16 .align 5
17 .word 0
18
191: subs r2, r2, #4 @ 1 do we have enough
20 blt 5f @ 1 bytes to align with?
21 cmp r3, #2 @ 1
22 strltb r1, [r0], #1 @ 1
23 strleb r1, [r0], #1 @ 1
24 strb r1, [r0], #1 @ 1
25 add r2, r2, r3 @ 1 (r2 = r2 - (4 - r3))
26/*
27 * The pointer is now aligned and the length is adjusted. Try doing the
28 * memzero again.
29 */
30
31ENTRY(memset)
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 * We need an extra register for this loop - save the return address and
44 * use the LR
45 */
46 str lr, [sp, #-4]!
47 mov ip, r1
48 mov lr, r1
49
502: subs r2, r2, #64
51 stmgeia r0!, {r1, r3, ip, lr} @ 64 bytes at a time.
52 stmgeia r0!, {r1, r3, ip, lr}
53 stmgeia r0!, {r1, r3, ip, lr}
54 stmgeia r0!, {r1, r3, ip, lr}
55 bgt 2b
56 LOADREGS(eqfd, sp!, {pc}) @ Now <64 bytes to go.
57/*
58 * No need to correct the count; we're only testing bits from now on
59 */
60 tst r2, #32
61 stmneia r0!, {r1, r3, ip, lr}
62 stmneia r0!, {r1, r3, ip, lr}
63 tst r2, #16
64 stmneia r0!, {r1, r3, ip, lr}
65 ldr lr, [sp], #4
66
674: tst r2, #8
68 stmneia r0!, {r1, r3}
69 tst r2, #4
70 strne r1, [r0], #4
71/*
72 * When we get here, we've got less than 4 bytes to zero. We
73 * may have an unaligned pointer as well.
74 */
755: tst r2, #2
76 strneb r1, [r0], #1
77 strneb r1, [r0], #1
78 tst r2, #1
79 strneb r1, [r0], #1
80 RETINSTR(mov,pc,lr)