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