1 /* SPDX-License-Identifier: GPL-2.0 */ !! 1 /*
2 /* $Id: strlen.S,v 1.2 2001/06/29 14:07:15 gni !! 2 * strlen.S (c) 1995 David Mosberger (davidm@cs.arizona.edu)
3 * 3 *
4 * "strlen" implementation of SuperH !! 4 * Finds length of a 0-terminated string. Optimized for the
5 * !! 5 * Alpha architecture:
6 * Copyright (C) 1999 Kaz Kojima <<
7 * 6 *
>> 7 * - memory accessed as aligned quadwords only
>> 8 * - uses bcmpge to compare 8 bytes in parallel
>> 9 * - does binary search to find 0 byte in last
>> 10 * quadword (HAKMEM needed 12 instructions to
>> 11 * do this instead of the 9 instructions that
>> 12 * binary search needs).
8 */ 13 */
9 14
10 /* size_t strlen (const char *s) */ !! 15 .set noreorder
>> 16 .set noat
>> 17
>> 18 .align 3
>> 19
>> 20 .globl strlen
>> 21 .ent strlen
>> 22
>> 23 strlen:
>> 24 ldq_u $1, 0($16) # load first quadword ($16 may be misaligned)
>> 25 lda $2, -1($31)
>> 26 insqh $2, $16, $2
>> 27 andnot $16, 7, $0
>> 28 or $2, $1, $1
>> 29 cmpbge $31, $1, $2 # $2 <- bitmask: bit i == 1 <==> i-th byte == 0
>> 30 bne $2, found
>> 31
>> 32 loop: ldq $1, 8($0)
>> 33 addq $0, 8, $0 # addr += 8
>> 34 nop # helps dual issue last two insns
>> 35 cmpbge $31, $1, $2
>> 36 beq $2, loop
>> 37
>> 38 found: blbs $2, done # make aligned case fast
>> 39 negq $2, $3
>> 40 and $2, $3, $2
>> 41
>> 42 and $2, 0x0f, $1
>> 43 addq $0, 4, $3
>> 44 cmoveq $1, $3, $0
>> 45
>> 46 and $2, 0x33, $1
>> 47 addq $0, 2, $3
>> 48 cmoveq $1, $3, $0
>> 49
>> 50 and $2, 0x55, $1
>> 51 addq $0, 1, $3
>> 52 cmoveq $1, $3, $0
>> 53
>> 54 done: subq $0, $16, $0
>> 55 ret $31, ($26)
11 56
12 #include <linux/linkage.h> !! 57 .end strlen
13 ENTRY(strlen) <<
14 mov r4,r0 <<
15 and #3,r0 <<
16 tst r0,r0 <<
17 bt/s 1f <<
18 mov #0,r2 <<
19 <<
20 add #-1,r0 <<
21 shll2 r0 <<
22 shll r0 <<
23 braf r0 <<
24 nop <<
25 <<
26 mov.b @r4+,r1 <<
27 tst r1,r1 <<
28 bt 8f <<
29 add #1,r2 <<
30 <<
31 mov.b @r4+,r1 <<
32 tst r1,r1 <<
33 bt 8f <<
34 add #1,r2 <<
35 <<
36 mov.b @r4+,r1 <<
37 tst r1,r1 <<
38 bt 8f <<
39 add #1,r2 <<
40 <<
41 1: <<
42 mov #0,r3 <<
43 2: <<
44 mov.l @r4+,r1 <<
45 cmp/str r3,r1 <<
46 bf/s 2b <<
47 add #4,r2 <<
48 <<
49 add #-4,r2 <<
50 #ifndef __LITTLE_ENDIAN__ <<
51 swap.b r1,r1 <<
52 swap.w r1,r1 <<
53 swap.b r1,r1 <<
54 #endif <<
55 extu.b r1,r0 <<
56 tst r0,r0 <<
57 bt/s 8f <<
58 shlr8 r1 <<
59 add #1,r2 <<
60 extu.b r1,r0 <<
61 tst r0,r0 <<
62 bt/s 8f <<
63 shlr8 r1 <<
64 add #1,r2 <<
65 extu.b r1,r0 <<
66 tst r0,r0 <<
67 bt 8f <<
68 add #1,r2 <<
69 8: <<
70 rts <<
71 mov r2,r0 <<
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