/*      $NetBSD: ffs.S,v 1.8 2020/03/10 08:15:44 rin Exp $      */

/*-
 * Copyright (c) 1990 The Regents of the University of California.
 * All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * the Systems Programming Group of the University of Utah Computer
 * Science Department.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 */

#include <machine/asm.h>

#if defined(LIBC_SCCS) && !defined(lint)
#if 0
        RCSID("from: @(#)ffs.s  5.1 (Berkeley) 5/12/90")
#else
        RCSID("$NetBSD: ffs.S,v 1.8 2020/03/10 08:15:44 rin Exp $")
#endif
#endif /* LIBC_SCCS and not lint */

/* bit = ffs(value) */

#ifdef _LIBC
WEAK_ALIAS(__ffssi2,ffs)
#else /* KERNEL */
/*
 * Our in-kernel linker does not understand weak references, which
 * prevents modules depended on __ffssi2 from being loaded. Also,
 * we do not provide ffs(9) as a kernel routine. Let's rename it!
 */
#define ffs __ffssi2
#endif

#if (!defined(__mc68010__) && !defined(__mcoldfire__)) || defined(__mcfisac__)

ENTRY(ffs)
        movl    4(%sp),%d0
        movl    %d0,%d1
        negl    %d0
        andl    %d0,%d1
        movql   #32,%d0
#if defined(__mcfisac__)
        ff1.l   %d1             | count leading zeros
#else
        bfffo   %d1{#0:#32},%d1
#endif
        subl    %d1,%d0
        rts
END(ffs)

#elif defined(__mcoldfire__)

ENTRY(ffs)
        clrl    %d0
        movl    4(%sp),%d1
        jeq     .L2             | return 0 if 0
.L1:
        addql   #1,%d0
        lsrl    #1,%d1          | shift low bit into carry
        jcc     .L1             | keep looping while carry is clear.
.L2:
        rts
END(ffs)

#else   /* __mc68010__ */

ENTRY(ffs)
        movl    4(%sp),%d0
        jeq     .L2
        movql   #31,%d1
.L1:    
        lsrl    #1,%d0
        dbcs    %d1,.L1
        movql   #32,%d0
        subl    %d1,%d0
.L2:
        rts
END(ffs)

#endif  /* __mc68010__ */