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