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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
1da177e4 LT |
2 | /* |
3 | * arch/alpha/lib/strncpy.S | |
4 | * Contributed by Richard Henderson (rth@tamu.edu) | |
5 | * | |
6 | * Copy no more than COUNT bytes of the null-terminated string from | |
7 | * SRC to DST. If SRC does not cover all of COUNT, the balance is | |
8 | * zeroed. | |
9 | * | |
10 | * Or, rather, if the kernel cared about that weird ANSI quirk. This | |
11 | * version has cropped that bit o' nastiness as well as assuming that | |
12 | * __stxncpy is in range of a branch. | |
13 | */ | |
00fc0e0d | 14 | #include <asm/export.h> |
1da177e4 LT |
15 | .set noat |
16 | .set noreorder | |
17 | ||
18 | .text | |
19 | ||
20 | .align 4 | |
21 | .globl strncpy | |
22 | .ent strncpy | |
23 | strncpy: | |
24 | .frame $30, 0, $26 | |
25 | .prologue 0 | |
26 | ||
27 | mov $16, $0 # set return value now | |
28 | beq $18, $zerolen | |
29 | unop | |
30 | bsr $23, __stxncpy # do the work of the copy | |
31 | ||
32 | unop | |
33 | bne $18, $multiword # do we have full words left? | |
34 | subq $24, 1, $3 # nope | |
35 | subq $27, 1, $4 | |
36 | ||
37 | or $3, $24, $3 # clear the bits between the last | |
38 | or $4, $27, $4 # written byte and the last byte in COUNT | |
fe4304ba | 39 | andnot $3, $4, $4 |
1da177e4 LT |
40 | zap $1, $4, $1 |
41 | ||
42 | stq_u $1, 0($16) | |
43 | ret | |
44 | ||
45 | .align 4 | |
46 | $multiword: | |
4d5c34ec IK |
47 | subq $27, 1, $2 # clear the final bits in the prev word |
48 | or $2, $27, $2 | |
1da177e4 LT |
49 | zapnot $1, $2, $1 |
50 | subq $18, 1, $18 | |
51 | ||
52 | stq_u $1, 0($16) | |
53 | addq $16, 8, $16 | |
54 | unop | |
55 | beq $18, 1f | |
56 | ||
57 | nop | |
58 | unop | |
59 | nop | |
60 | blbc $18, 0f | |
61 | ||
62 | stq_u $31, 0($16) # zero one word | |
63 | subq $18, 1, $18 | |
64 | addq $16, 8, $16 | |
65 | beq $18, 1f | |
66 | ||
67 | 0: stq_u $31, 0($16) # zero two words | |
68 | subq $18, 2, $18 | |
69 | stq_u $31, 8($16) | |
70 | addq $16, 16, $16 | |
71 | bne $18, 0b | |
72 | ||
73 | 1: ldq_u $1, 0($16) # clear the leading bits in the final word | |
4d5c34ec IK |
74 | subq $24, 1, $2 |
75 | or $2, $24, $2 | |
1da177e4 LT |
76 | |
77 | zap $1, $2, $1 | |
78 | stq_u $1, 0($16) | |
79 | $zerolen: | |
80 | ret | |
81 | ||
82 | .end strncpy | |
00fc0e0d | 83 | EXPORT_SYMBOL(strncpy) |