1 /* SPDX-License-Identifier: GPL-2.0 */
2 /*
3 * strlen.S (c) 1995 David Mosberger (davidm@c
4 *
5 * Finds length of a 0-terminated string. Opt
6 * Alpha architecture:
7 *
8 * - memory accessed as aligned quadwords
9 * - uses bcmpge to compare 8 bytes in pa
10 * - does binary search to find 0 byte in
11 * quadword (HAKMEM needed 12 instructi
12 * do this instead of the 9 instruction
13 * binary search needs).
14 */
15 #include <linux/export.h>
16 .set noreorder
17 .set noat
18
19 .align 3
20
21 .globl strlen
22 .ent strlen
23
24 strlen:
25 ldq_u $1, 0($16) # load first q
26 lda $2, -1($31)
27 insqh $2, $16, $2
28 andnot $16, 7, $0
29 or $2, $1, $1
30 cmpbge $31, $1, $2 # $2 <- bitma
31 bne $2, found
32
33 loop: ldq $1, 8($0)
34 addq $0, 8, $0 # addr += 8
35 nop # helps dual i
36 cmpbge $31, $1, $2
37 beq $2, loop
38
39 found: blbs $2, done # make aligned
40 negq $2, $3
41 and $2, $3, $2
42
43 and $2, 0x0f, $1
44 addq $0, 4, $3
45 cmoveq $1, $3, $0
46
47 and $2, 0x33, $1
48 addq $0, 2, $3
49 cmoveq $1, $3, $0
50
51 and $2, 0x55, $1
52 addq $0, 1, $3
53 cmoveq $1, $3, $0
54
55 done: subq $0, $16, $0
56 ret $31, ($26)
57
58 .end strlen
59 EXPORT_SYMBOL(strlen)
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