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1da177e4 LT |
1 | /* |
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 | ||
19 | 1: subs r2, r2, #4 @ 1 do we have enough | |
20 | blt 5f @ 1 bytes to align with? | |
21 | cmp r3, #2 @ 1 | |
455bd4c4 ID |
22 | strltb r1, [ip], #1 @ 1 |
23 | strleb r1, [ip], #1 @ 1 | |
24 | strb r1, [ip], #1 @ 1 | |
1da177e4 LT |
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 | |
59f0cb0f | 28 | * memset again. |
1da177e4 LT |
29 | */ |
30 | ||
31 | ENTRY(memset) | |
455bd4c4 ID |
32 | /* |
33 | * Preserve the contents of r0 for the return value. | |
34 | */ | |
35 | mov ip, r0 | |
36 | ands r3, ip, #3 @ 1 unaligned? | |
1da177e4 LT |
37 | bne 1b @ 1 |
38 | /* | |
455bd4c4 | 39 | * we know that the pointer in ip is aligned to a word boundary. |
1da177e4 LT |
40 | */ |
41 | orr r1, r1, r1, lsl #8 | |
42 | orr r1, r1, r1, lsl #16 | |
43 | mov r3, r1 | |
44 | cmp r2, #16 | |
45 | blt 4f | |
f91a8dcc NP |
46 | |
47 | #if ! CALGN(1)+0 | |
48 | ||
1da177e4 | 49 | /* |
455bd4c4 | 50 | * We need 2 extra registers for this loop - use r8 and the LR |
1da177e4 | 51 | */ |
455bd4c4 ID |
52 | stmfd sp!, {r8, lr} |
53 | mov r8, r1 | |
1da177e4 LT |
54 | mov lr, r1 |
55 | ||
56 | 2: subs r2, r2, #64 | |
455bd4c4 ID |
57 | stmgeia ip!, {r1, r3, r8, lr} @ 64 bytes at a time. |
58 | stmgeia ip!, {r1, r3, r8, lr} | |
59 | stmgeia ip!, {r1, r3, r8, lr} | |
60 | stmgeia ip!, {r1, r3, r8, lr} | |
1da177e4 | 61 | bgt 2b |
455bd4c4 | 62 | ldmeqfd sp!, {r8, pc} @ Now <64 bytes to go. |
1da177e4 LT |
63 | /* |
64 | * No need to correct the count; we're only testing bits from now on | |
65 | */ | |
66 | tst r2, #32 | |
455bd4c4 ID |
67 | stmneia ip!, {r1, r3, r8, lr} |
68 | stmneia ip!, {r1, r3, r8, lr} | |
1da177e4 | 69 | tst r2, #16 |
455bd4c4 ID |
70 | stmneia ip!, {r1, r3, r8, lr} |
71 | ldmfd sp!, {r8, lr} | |
1da177e4 | 72 | |
f91a8dcc NP |
73 | #else |
74 | ||
75 | /* | |
76 | * This version aligns the destination pointer in order to write | |
77 | * whole cache lines at once. | |
78 | */ | |
79 | ||
455bd4c4 | 80 | stmfd sp!, {r4-r8, lr} |
f91a8dcc NP |
81 | mov r4, r1 |
82 | mov r5, r1 | |
83 | mov r6, r1 | |
84 | mov r7, r1 | |
455bd4c4 | 85 | mov r8, r1 |
f91a8dcc NP |
86 | mov lr, r1 |
87 | ||
88 | cmp r2, #96 | |
455bd4c4 | 89 | tstgt ip, #31 |
f91a8dcc NP |
90 | ble 3f |
91 | ||
455bd4c4 ID |
92 | and r8, ip, #31 |
93 | rsb r8, r8, #32 | |
94 | sub r2, r2, r8 | |
95 | movs r8, r8, lsl #(32 - 4) | |
96 | stmcsia ip!, {r4, r5, r6, r7} | |
97 | stmmiia ip!, {r4, r5} | |
98 | tst r8, #(1 << 30) | |
99 | mov r8, r1 | |
100 | strne r1, [ip], #4 | |
f91a8dcc NP |
101 | |
102 | 3: subs r2, r2, #64 | |
455bd4c4 ID |
103 | stmgeia ip!, {r1, r3-r8, lr} |
104 | stmgeia ip!, {r1, r3-r8, lr} | |
f91a8dcc | 105 | bgt 3b |
455bd4c4 | 106 | ldmeqfd sp!, {r4-r8, pc} |
f91a8dcc NP |
107 | |
108 | tst r2, #32 | |
455bd4c4 | 109 | stmneia ip!, {r1, r3-r8, lr} |
f91a8dcc | 110 | tst r2, #16 |
455bd4c4 ID |
111 | stmneia ip!, {r4-r7} |
112 | ldmfd sp!, {r4-r8, lr} | |
f91a8dcc NP |
113 | |
114 | #endif | |
115 | ||
1da177e4 | 116 | 4: tst r2, #8 |
455bd4c4 | 117 | stmneia ip!, {r1, r3} |
1da177e4 | 118 | tst r2, #4 |
455bd4c4 | 119 | strne r1, [ip], #4 |
1da177e4 LT |
120 | /* |
121 | * When we get here, we've got less than 4 bytes to zero. We | |
122 | * may have an unaligned pointer as well. | |
123 | */ | |
124 | 5: tst r2, #2 | |
455bd4c4 ID |
125 | strneb r1, [ip], #1 |
126 | strneb r1, [ip], #1 | |
1da177e4 | 127 | tst r2, #1 |
455bd4c4 | 128 | strneb r1, [ip], #1 |
7999d8d7 | 129 | mov pc, lr |
93ed3970 | 130 | ENDPROC(memset) |