1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * arch/alpha/lib/strncat.S 3 * arch/alpha/lib/strncat.S
4 * Contributed by Richard Henderson (rth@tamu. 4 * Contributed by Richard Henderson (rth@tamu.edu)
5 * 5 *
6 * Append no more than COUNT characters from t 6 * Append no more than COUNT characters from the null-terminated string SRC
7 * to the null-terminated string DST. Always 7 * to the null-terminated string DST. Always null-terminate the new DST.
8 * 8 *
9 * This differs slightly from the semantics in 9 * This differs slightly from the semantics in libc in that we never write
10 * past count, whereas libc may write to count 10 * past count, whereas libc may write to count+1. This follows the generic
11 * implementation in lib/string.c and is, IMHO 11 * implementation in lib/string.c and is, IMHO, more sensible.
12 */ 12 */
13 #include <linux/export.h> 13 #include <linux/export.h>
14 .text 14 .text
15 15
16 .align 3 16 .align 3
17 .globl strncat 17 .globl strncat
18 .ent strncat 18 .ent strncat
19 strncat: 19 strncat:
20 .frame $30, 0, $26 20 .frame $30, 0, $26
21 .prologue 0 21 .prologue 0
22 22
23 mov $16, $0 # set up retur 23 mov $16, $0 # set up return value
24 beq $18, $zerocount 24 beq $18, $zerocount
25 25
26 /* Find the end of the string. */ 26 /* Find the end of the string. */
27 27
28 ldq_u $1, 0($16) # load first q 28 ldq_u $1, 0($16) # load first quadword ($16 may be misaligned)
29 lda $2, -1($31) 29 lda $2, -1($31)
30 insqh $2, $16, $2 30 insqh $2, $16, $2
31 andnot $16, 7, $16 31 andnot $16, 7, $16
32 or $2, $1, $1 32 or $2, $1, $1
33 cmpbge $31, $1, $2 # bits set iff 33 cmpbge $31, $1, $2 # bits set iff byte == 0
34 bne $2, $found 34 bne $2, $found
35 35
36 $loop: ldq $1, 8($16) 36 $loop: ldq $1, 8($16)
37 addq $16, 8, $16 37 addq $16, 8, $16
38 cmpbge $31, $1, $2 38 cmpbge $31, $1, $2
39 beq $2, $loop 39 beq $2, $loop
40 40
41 $found: negq $2, $3 # clear all bu 41 $found: negq $2, $3 # clear all but least set bit
42 and $2, $3, $2 42 and $2, $3, $2
43 43
44 and $2, 0xf0, $3 # binary searc 44 and $2, 0xf0, $3 # binary search for that set bit
45 and $2, 0xcc, $4 45 and $2, 0xcc, $4
46 and $2, 0xaa, $5 46 and $2, 0xaa, $5
47 cmovne $3, 4, $3 47 cmovne $3, 4, $3
48 cmovne $4, 2, $4 48 cmovne $4, 2, $4
49 cmovne $5, 1, $5 49 cmovne $5, 1, $5
50 addq $3, $4, $3 50 addq $3, $4, $3
51 addq $16, $5, $16 51 addq $16, $5, $16
52 addq $16, $3, $16 52 addq $16, $3, $16
53 53
54 /* Now do the append. */ 54 /* Now do the append. */
55 55
56 bsr $23, __stxncpy 56 bsr $23, __stxncpy
57 57
58 /* Worry about the null termination. 58 /* Worry about the null termination. */
59 59
60 zapnot $1, $27, $2 # was last byt 60 zapnot $1, $27, $2 # was last byte a null?
61 bne $2, 0f 61 bne $2, 0f
62 ret 62 ret
63 63
64 0: cmplt $27, $24, $2 # did we fill 64 0: cmplt $27, $24, $2 # did we fill the buffer completely?
65 or $2, $18, $2 65 or $2, $18, $2
66 bne $2, 2f 66 bne $2, 2f
67 67
68 and $24, 0x80, $2 # no zero next 68 and $24, 0x80, $2 # no zero next byte
69 bne $2, 1f 69 bne $2, 1f
70 70
71 /* Here there are bytes left in the cu 71 /* Here there are bytes left in the current word. Clear one. */
72 addq $24, $24, $24 # end-of-count 72 addq $24, $24, $24 # end-of-count bit <<= 1
73 2: zap $1, $24, $1 73 2: zap $1, $24, $1
74 stq_u $1, 0($16) 74 stq_u $1, 0($16)
75 ret 75 ret
76 76
77 1: /* Here we must read the next DST word 77 1: /* Here we must read the next DST word and clear the first byte. */
78 ldq_u $1, 8($16) 78 ldq_u $1, 8($16)
79 zap $1, 1, $1 79 zap $1, 1, $1
80 stq_u $1, 8($16) 80 stq_u $1, 8($16)
81 81
82 $zerocount: 82 $zerocount:
83 ret 83 ret
84 84
85 .end strncat 85 .end strncat
86 EXPORT_SYMBOL(strncat) 86 EXPORT_SYMBOL(strncat)
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