usr/src/lib/libbc/libc/gen/common/sparc/ffs.s

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License, Version 1.0 only
   6  * (the "License").  You may not use this file except in compliance
   7  * with the License.
   8  *
   9  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
  10  * or http://www.opensolaris.org/os/licensing.
  11  * See the License for the specific language governing permissions
  12  * and limitations under the License.
  13  *
  14  * When distributing Covered Code, include this CDDL HEADER in each
  15  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  16  * If applicable, add the following below this CDDL HEADER, with the
  17  * fields enclosed by brackets "[]" replaced with your own identifying
  18  * information: Portions Copyright [yyyy] [name of copyright owner]
  19  *
  20  * CDDL HEADER END
  21  */
  22 /*
  23  * Copyright 1992 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 !       .seg    "data"
  28 !       .asciz ident    "%Z%%M% %I%     %E% SMI"
  29         .seg    ".text"
  30
  31         .file   "ffs.s"
  32
  33 #include <sun4/asm_linkage.h>
  34
  35         ENTRY(ffs)
  36         tst     %o0             ! if zero, done
  37         bz      2f
  38         clr     %o1             ! delay slot, return zero if no bit set
  39 1:
  40         inc     %o1             ! bit that will get checked
  41         btst    1, %o0
  42         be      1b              ! if bit is zero, keep checking
  43         srl     %o0, 1, %o0     ! shift input right until we hit a 1 bit
  44 2:
  45         retl
  46         mov     %o1, %o0        ! return value is in o1
  47         SET_SIZE(ffs)