1/* Copyright (C) 1996-2021 Free Software Foundation, Inc.
2   This file is part of the GNU C Library.
3
4   The GNU C Library is free software; you can redistribute it and/or
5   modify it under the terms of the GNU Lesser General Public
6   License as published by the Free Software Foundation; either
7   version 2.1 of the License, or (at your option) any later version.
8
9   The GNU C Library is distributed in the hope that it will be useful,
10   but WITHOUT ANY WARRANTY; without even the implied warranty of
11   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
12   Lesser General Public License for more details.
13
14   You should have received a copy of the GNU Lesser General Public
15   License along with the GNU C Library.  If not, see
16   <https://www.gnu.org/licenses/>.  */
17
18/* Finds the first bit set in an integer.  Optimized for the Alpha
19   architecture.  */
20
21#include <sysdep.h>
22
23	.set noreorder
24	.set noat
25
26
27ENTRY(__ffs)
28#ifdef PROF
29	ldgp	gp, 0(pv)
30	lda	AT, _mcount
31	jsr	AT, (AT), _mcount
32	.prologue 1
33	zap	$16, 0xF0, $16
34	br	$ffsl..ng
35#else
36	.prologue 0
37	zap	$16, 0xF0, $16
38	# FALLTHRU
39#endif
40END(__ffs)
41
42	.align 4
43ENTRY(ffsl)
44#ifdef PROF
45	ldgp	gp, 0(pv)
46	lda	AT, _mcount
47	jsr	AT, (AT), _mcount
48	.prologue 1
49$ffsl..ng:
50#else
51	.prologue 0
52#endif
53	not	$16, $1		# e0    :
54	ldi	$2, -1		# .. e1 :
55	cmpbge	$1, $2, $3	# e0    : bit N == 1 for byte N == 0
56	clr	$0		# .. e1 :
57	addq	$3, 1, $4	# e0    :
58	bic	$4, $3, $3	# e1    : bit N == 1 for first byte N != 0
59	and	$3, 0xF0, $4	# e0    :
60	and	$3, 0xCC, $5	# .. e1 :
61	and	$3, 0xAA, $6	# e0    :
62	cmovne	$4, 4, $0	# .. e1 :
63	cmovne	$5, 2, $5	# e0    :
64	cmovne  $6, 1, $6	# .. e1 :
65	addl	$0, $5, $0	# e0    :
66	addl	$0, $6, $0	# e1    : $0 == N
67	extbl	$16, $0, $1	# e0    : $1 == byte N
68	ldi	$2, 1		# .. e1 :
69	negq	$1, $3		# e0    :
70	and	$3, $1, $3	# e1    : bit N == least bit set of byte N
71	and	$3, 0xF0, $4	# e0    :
72	and	$3, 0xCC, $5	# .. e1 :
73	and	$3, 0xAA, $6	# e0    :
74	cmovne	$4, 5, $2	# .. e1 :
75	cmovne	$5, 2, $5	# e0    :
76	cmovne	$6, 1, $6	# .. e1 :
77	s8addl	$0, $2, $0	# e0    : mult byte ofs by 8 and sum
78	addl	$5, $6, $5	# .. e1 :
79	addl	$0, $5, $0	# e0    :
80	nop			# .. e1 :
81	cmoveq	$16, 0, $0	# e0    : trap input == 0 case.
82	ret			# .. e1 : 18
83
84END(ffsl)
85
86weak_alias (__ffs, ffs)
87libc_hidden_def (__ffs)
88libc_hidden_builtin_def (ffs)
89weak_extern (ffsl)
90weak_alias (ffsl, ffsll)
91