1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * arch/alpha/lib/ev67-strncat.S
4 * 21264 version contributed by Rick Gorton <ri
5 *
6 * Append no more than COUNT characters from t
7 * to the null-terminated string DST. Always
8 *
9 * This differs slightly from the semantics in
10 * past count, whereas libc may write to count
11 * implementation in lib/string.c and is, IMHO
12 *
13 * Much of the information about 21264 schedul
14 * Compiler Writer's Guide for the Alpha
15 * abbreviated as 'CWG' in other comments
16 * ftp.digital.com/pub/Digital/info/semic
17 * Scheduling notation:
18 * E - either cluster
19 * U - upper subcluster; U0 - subcl
20 * L - lower subcluster; L0 - subcl
21 * Try not to change the actual algorithm if p
22 */
23
24 #include <linux/export.h>
25 .text
26
27 .align 4
28 .globl strncat
29 .ent strncat
30 strncat:
31 .frame $30, 0, $26
32 .prologue 0
33
34 mov $16, $0 # set up retur
35 beq $18, $zerocount # U :
36 /* Find the end of the string. */
37 ldq_u $1, 0($16) # L : load fir
38 lda $2, -1($31) # E :
39
40 insqh $2, $0, $2 # U :
41 andnot $16, 7, $16 # E :
42 nop # E :
43 or $2, $1, $1 # E :
44
45 nop # E :
46 nop # E :
47 cmpbge $31, $1, $2 # E : bits set
48 bne $2, $found # U :
49
50 $loop: ldq $1, 8($16) # L :
51 addq $16, 8, $16 # E :
52 cmpbge $31, $1, $2 # E :
53 beq $2, $loop # U :
54
55 $found: cttz $2, $3 # U0 :
56 addq $16, $3, $16 # E :
57 nop # E :
58 bsr $23, __stxncpy # L0 :/* Now d
59
60 /* Worry about the null termination.
61
62 zapnot $1, $27, $2 # U : was last
63 cmplt $27, $24, $5 # E : did we f
64 bne $2, 0f # U :
65 ret # L0 :
66
67 0: or $5, $18, $2 # E :
68 nop
69 bne $2, 2f # U :
70 and $24, 0x80, $3 # E : no zero
71
72 nop # E :
73 bne $3, 1f # U :
74 /* Here there are bytes left in the cu
75 addq $24, $24, $24 # E : end-of-c
76 nop # E :
77
78 2: zap $1, $24, $1 # U :
79 nop # E :
80 stq_u $1, 0($16) # L :
81 ret # L0 :
82
83 1: /* Here we must clear the first byte o
84 stb $31, 8($16) # L :
85 nop # E :
86 nop # E :
87 ret # L0 :
88
89 $zerocount:
90 nop # E :
91 nop # E :
92 nop # E :
93 ret # L0 :
94
95 .end strncat
96 EXPORT_SYMBOL(strncat)
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