Merge tag 'platform-drivers-x86-v4.2-1' of git://git.infradead.org/users/dvhart/linux...
[linux-2.6-block.git] / arch / arm / lib / memzero.S
CommitLineData
1da177e4
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1/*
2 * linux/arch/arm/lib/memzero.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#include <linux/linkage.h>
11#include <asm/assembler.h>
20cb6abf 12#include <asm/unwind.h>
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13
14 .text
15 .align 5
16 .word 0
17/*
18 * Align the pointer in r0. r3 contains the number of bytes that we are
19 * mis-aligned by, and r1 is the number of bytes. If r1 < 4, then we
20 * don't bother; we use byte stores instead.
21 */
20cb6abf 22UNWIND( .fnstart )
1da177e4
LT
231: subs r1, r1, #4 @ 1 do we have enough
24 blt 5f @ 1 bytes to align with?
25 cmp r3, #2 @ 1
26 strltb r2, [r0], #1 @ 1
27 strleb r2, [r0], #1 @ 1
28 strb r2, [r0], #1 @ 1
29 add r1, r1, r3 @ 1 (r1 = r1 - (4 - r3))
30/*
31 * The pointer is now aligned and the length is adjusted. Try doing the
32 * memzero again.
33 */
34
35ENTRY(__memzero)
36 mov r2, #0 @ 1
37 ands r3, r0, #3 @ 1 unaligned?
38 bne 1b @ 1
39/*
40 * r3 = 0, and we know that the pointer in r0 is aligned to a word boundary.
41 */
42 cmp r1, #16 @ 1 we can skip this chunk if we
43 blt 4f @ 1 have < 16 bytes
f91a8dcc
NP
44
45#if ! CALGN(1)+0
46
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47/*
48 * We need an extra register for this loop - save the return address and
49 * use the LR
50 */
51 str lr, [sp, #-4]! @ 1
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LY
52UNWIND( .fnend )
53UNWIND( .fnstart )
54UNWIND( .save {lr} )
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55 mov ip, r2 @ 1
56 mov lr, r2 @ 1
57
583: subs r1, r1, #64 @ 1 write 32 bytes out per loop
59 stmgeia r0!, {r2, r3, ip, lr} @ 4
60 stmgeia r0!, {r2, r3, ip, lr} @ 4
61 stmgeia r0!, {r2, r3, ip, lr} @ 4
62 stmgeia r0!, {r2, r3, ip, lr} @ 4
63 bgt 3b @ 1
1b93a717 64 ldmeqfd sp!, {pc} @ 1/2 quick exit
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65/*
66 * No need to correct the count; we're only testing bits from now on
67 */
68 tst r1, #32 @ 1
69 stmneia r0!, {r2, r3, ip, lr} @ 4
70 stmneia r0!, {r2, r3, ip, lr} @ 4
71 tst r1, #16 @ 1 16 bytes or more?
72 stmneia r0!, {r2, r3, ip, lr} @ 4
73 ldr lr, [sp], #4 @ 1
20cb6abf 74UNWIND( .fnend )
1da177e4 75
f91a8dcc
NP
76#else
77
78/*
79 * This version aligns the destination pointer in order to write
80 * whole cache lines at once.
81 */
82
83 stmfd sp!, {r4-r7, lr}
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LY
84UNWIND( .fnend )
85UNWIND( .fnstart )
86UNWIND( .save {r4-r7, lr} )
f91a8dcc
NP
87 mov r4, r2
88 mov r5, r2
89 mov r6, r2
90 mov r7, r2
91 mov ip, r2
92 mov lr, r2
93
94 cmp r1, #96
95 andgts ip, r0, #31
96 ble 3f
97
98 rsb ip, ip, #32
99 sub r1, r1, ip
100 movs ip, ip, lsl #(32 - 4)
101 stmcsia r0!, {r4, r5, r6, r7}
102 stmmiia r0!, {r4, r5}
103 movs ip, ip, lsl #2
104 strcs r2, [r0], #4
105
1063: subs r1, r1, #64
107 stmgeia r0!, {r2-r7, ip, lr}
108 stmgeia r0!, {r2-r7, ip, lr}
109 bgt 3b
110 ldmeqfd sp!, {r4-r7, pc}
111
112 tst r1, #32
113 stmneia r0!, {r2-r7, ip, lr}
114 tst r1, #16
115 stmneia r0!, {r4-r7}
116 ldmfd sp!, {r4-r7, lr}
20cb6abf 117UNWIND( .fnend )
f91a8dcc
NP
118
119#endif
120
20cb6abf 121UNWIND( .fnstart )
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1224: tst r1, #8 @ 1 8 bytes or more?
123 stmneia r0!, {r2, r3} @ 2
124 tst r1, #4 @ 1 4 bytes or more?
125 strne r2, [r0], #4 @ 1
126/*
127 * When we get here, we've got less than 4 bytes to zero. We
128 * may have an unaligned pointer as well.
129 */
1305: tst r1, #2 @ 1 2 bytes or more?
131 strneb r2, [r0], #1 @ 1
132 strneb r2, [r0], #1 @ 1
133 tst r1, #1 @ 1 a byte left over
134 strneb r2, [r0], #1 @ 1
6ebbf2ce 135 ret lr @ 1
20cb6abf 136UNWIND( .fnend )
93ed3970 137ENDPROC(__memzero)