1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
|
/* Copyright (C) 1996, 1997, 1998, 2004 Free Software Foundation, Inc.
Contributed by David Mosberger (davidm@cs.arizona.edu).
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library. If not, see
<http://www.gnu.org/licenses/>. */
/* Finds the first bit set in an integer. Optimized for the Alpha
architecture. */
#include <sysdep.h>
.set noreorder
.set noat
ENTRY(__ffs)
#ifdef PROF
ldgp gp, 0(pv)
lda AT, _mcount
jsr AT, (AT), _mcount
.prologue 1
zap $16, 0xF0, $16
br $ffsl..ng
#else
.prologue 0
zap $16, 0xF0, $16
# FALLTHRU
#endif
END(__ffs)
.align 4
ENTRY(ffsl)
#ifdef PROF
ldgp gp, 0(pv)
lda AT, _mcount
jsr AT, (AT), _mcount
.prologue 1
$ffsl..ng:
#else
.prologue 0
#endif
not $16, $1 # e0 :
ldi $2, -1 # .. e1 :
cmpbge $1, $2, $3 # e0 : bit N == 1 for byte N == 0
clr $0 # .. e1 :
addq $3, 1, $4 # e0 :
bic $4, $3, $3 # e1 : bit N == 1 for first byte N != 0
and $3, 0xF0, $4 # e0 :
and $3, 0xCC, $5 # .. e1 :
and $3, 0xAA, $6 # e0 :
cmovne $4, 4, $0 # .. e1 :
cmovne $5, 2, $5 # e0 :
cmovne $6, 1, $6 # .. e1 :
addl $0, $5, $0 # e0 :
addl $0, $6, $0 # e1 : $0 == N
extbl $16, $0, $1 # e0 : $1 == byte N
ldi $2, 1 # .. e1 :
negq $1, $3 # e0 :
and $3, $1, $3 # e1 : bit N == least bit set of byte N
and $3, 0xF0, $4 # e0 :
and $3, 0xCC, $5 # .. e1 :
and $3, 0xAA, $6 # e0 :
cmovne $4, 5, $2 # .. e1 :
cmovne $5, 2, $5 # e0 :
cmovne $6, 1, $6 # .. e1 :
s8addl $0, $2, $0 # e0 : mult byte ofs by 8 and sum
addl $5, $6, $5 # .. e1 :
addl $0, $5, $0 # e0 :
nop # .. e1 :
cmoveq $16, 0, $0 # e0 : trap input == 0 case.
ret # .. e1 : 18
END(ffsl)
weak_alias (__ffs, ffs)
libc_hidden_builtin_def (ffs)
weak_extern (ffsl)
weak_alias (ffsl, ffsll)
|
