1/*        $NetBSD: ffs.S,v 1.8 2020/03/10 08:15:44 rin Exp $          */
2
3/*-
4 * Copyright (c) 1990 The Regents of the University of California.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to Berkeley by
8 * the Systems Programming Group of the University of Utah Computer
9 * Science Department.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 *    notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 *    notice, this list of conditions and the following disclaimer in the
18 *    documentation and/or other materials provided with the distribution.
19 * 3. Neither the name of the University nor the names of its contributors
20 *    may be used to endorse or promote products derived from this software
21 *    without specific prior written permission.
22 *
23 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33 * SUCH DAMAGE.
34 */
35
36#include <machine/asm.h>
37
38#if defined(LIBC_SCCS) && !defined(lint)
39#if 0
40          RCSID("from: @(#)ffs.s        5.1 (Berkeley) 5/12/90")
41#else
42          RCSID("$NetBSD: ffs.S,v 1.8 2020/03/10 08:15:44 rin Exp $")
43#endif
44#endif /* LIBC_SCCS and not lint */
45
46/* bit = ffs(value) */
47
48#ifdef _LIBC
49WEAK_ALIAS(__ffssi2,ffs)
50#else /* KERNEL */
51/*
52 * Our in-kernel linker does not understand weak references, which
53 * prevents modules depended on __ffssi2 from being loaded. Also,
54 * we do not provide ffs(9) as a kernel routine. Let's rename it!
55 */
56#define ffs __ffssi2
57#endif
58
59#if (!defined(__mc68010__) && !defined(__mcoldfire__)) || defined(__mcfisac__)
60
61ENTRY(ffs)
62          movl      4(%sp),%d0
63          movl      %d0,%d1
64          negl      %d0
65          andl      %d0,%d1
66          movql     #32,%d0
67#if defined(__mcfisac__)
68          ff1.l     %d1                 | count leading zeros
69#else
70          bfffo     %d1{#0:#32},%d1
71#endif
72          subl      %d1,%d0
73          rts
74END(ffs)
75
76#elif defined(__mcoldfire__)
77
78ENTRY(ffs)
79          clrl      %d0
80          movl      4(%sp),%d1
81          jeq       .L2                 | return 0 if 0
82.L1:
83          addql     #1,%d0
84          lsrl      #1,%d1              | shift low bit into carry
85          jcc       .L1                 | keep looping while carry is clear.
86.L2:
87          rts
88END(ffs)
89
90#else     /* __mc68010__ */
91
92ENTRY(ffs)
93          movl      4(%sp),%d0
94          jeq       .L2
95          movql     #31,%d1
96.L1:
97          lsrl      #1,%d0
98          dbcs      %d1,.L1
99          movql     #32,%d0
100          subl      %d1,%d0
101.L2:
102          rts
103END(ffs)
104
105#endif    /* __mc68010__ */
106