1 /* SPDX-License-Identifier: GPL-2.0 */ 1 /* SPDX-License-Identifier: GPL-2.0 */
2 /* 2 /*
3 * arch/alpha/lib/ev67-strncat.S 3 * arch/alpha/lib/ev67-strncat.S
4 * 21264 version contributed by Rick Gorton <ri 4 * 21264 version contributed by Rick Gorton <rick.gorton@api-networks.com>
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 * Much of the information about 21264 schedul 13 * Much of the information about 21264 scheduling/coding comes from:
14 * Compiler Writer's Guide for the Alpha 14 * Compiler Writer's Guide for the Alpha 21264
15 * abbreviated as 'CWG' in other comments 15 * abbreviated as 'CWG' in other comments here
16 * ftp.digital.com/pub/Digital/info/semic 16 * ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
17 * Scheduling notation: 17 * Scheduling notation:
18 * E - either cluster 18 * E - either cluster
19 * U - upper subcluster; U0 - subcl 19 * U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
20 * L - lower subcluster; L0 - subcl 20 * L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
21 * Try not to change the actual algorithm if p 21 * Try not to change the actual algorithm if possible for consistency.
22 */ 22 */
23 23
24 #include <linux/export.h> 24 #include <linux/export.h>
25 .text 25 .text
26 26
27 .align 4 27 .align 4
28 .globl strncat 28 .globl strncat
29 .ent strncat 29 .ent strncat
30 strncat: 30 strncat:
31 .frame $30, 0, $26 31 .frame $30, 0, $26
32 .prologue 0 32 .prologue 0
33 33
34 mov $16, $0 # set up retur 34 mov $16, $0 # set up return value
35 beq $18, $zerocount # U : 35 beq $18, $zerocount # U :
36 /* Find the end of the string. */ 36 /* Find the end of the string. */
37 ldq_u $1, 0($16) # L : load fir 37 ldq_u $1, 0($16) # L : load first quadword ($16 may be misaligned)
38 lda $2, -1($31) # E : 38 lda $2, -1($31) # E :
39 39
40 insqh $2, $0, $2 # U : 40 insqh $2, $0, $2 # U :
41 andnot $16, 7, $16 # E : 41 andnot $16, 7, $16 # E :
42 nop # E : 42 nop # E :
43 or $2, $1, $1 # E : 43 or $2, $1, $1 # E :
44 44
45 nop # E : 45 nop # E :
46 nop # E : 46 nop # E :
47 cmpbge $31, $1, $2 # E : bits set 47 cmpbge $31, $1, $2 # E : bits set iff byte == 0
48 bne $2, $found # U : 48 bne $2, $found # U :
49 49
50 $loop: ldq $1, 8($16) # L : 50 $loop: ldq $1, 8($16) # L :
51 addq $16, 8, $16 # E : 51 addq $16, 8, $16 # E :
52 cmpbge $31, $1, $2 # E : 52 cmpbge $31, $1, $2 # E :
53 beq $2, $loop # U : 53 beq $2, $loop # U :
54 54
55 $found: cttz $2, $3 # U0 : 55 $found: cttz $2, $3 # U0 :
56 addq $16, $3, $16 # E : 56 addq $16, $3, $16 # E :
57 nop # E : 57 nop # E :
58 bsr $23, __stxncpy # L0 :/* Now d 58 bsr $23, __stxncpy # L0 :/* Now do the append. */
59 59
60 /* Worry about the null termination. 60 /* Worry about the null termination. */
61 61
62 zapnot $1, $27, $2 # U : was last 62 zapnot $1, $27, $2 # U : was last byte a null?
63 cmplt $27, $24, $5 # E : did we f 63 cmplt $27, $24, $5 # E : did we fill the buffer completely?
64 bne $2, 0f # U : 64 bne $2, 0f # U :
65 ret # L0 : 65 ret # L0 :
66 66
67 0: or $5, $18, $2 # E : 67 0: or $5, $18, $2 # E :
68 nop 68 nop
69 bne $2, 2f # U : 69 bne $2, 2f # U :
70 and $24, 0x80, $3 # E : no zero 70 and $24, 0x80, $3 # E : no zero next byte
71 71
72 nop # E : 72 nop # E :
73 bne $3, 1f # U : 73 bne $3, 1f # U :
74 /* Here there are bytes left in the cu 74 /* Here there are bytes left in the current word. Clear one. */
75 addq $24, $24, $24 # E : end-of-c 75 addq $24, $24, $24 # E : end-of-count bit <<= 1
76 nop # E : 76 nop # E :
77 77
78 2: zap $1, $24, $1 # U : 78 2: zap $1, $24, $1 # U :
79 nop # E : 79 nop # E :
80 stq_u $1, 0($16) # L : 80 stq_u $1, 0($16) # L :
81 ret # L0 : 81 ret # L0 :
82 82
83 1: /* Here we must clear the first byte o 83 1: /* Here we must clear the first byte of the next DST word */
84 stb $31, 8($16) # L : 84 stb $31, 8($16) # L :
85 nop # E : 85 nop # E :
86 nop # E : 86 nop # E :
87 ret # L0 : 87 ret # L0 :
88 88
89 $zerocount: 89 $zerocount:
90 nop # E : 90 nop # E :
91 nop # E : 91 nop # E :
92 nop # E : 92 nop # E :
93 ret # L0 : 93 ret # L0 :
94 94
95 .end strncat 95 .end strncat
96 EXPORT_SYMBOL(strncat) 96 EXPORT_SYMBOL(strncat)
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