bsd/dev/ppc/ffs.s

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_OSREFERENCE_HEADER_START@
   5  *
   6  * This file contains Original Code and/or Modifications of Original Code
   7  * as defined in and that are subject to the Apple Public Source License
   8  * Version 2.0 (the 'License'). You may not use this file except in
   9  * compliance with the License.  The rights granted to you under the
  10  * License may not be used to create, or enable the creation or
  11  * redistribution of, unlawful or unlicensed copies of an Apple operating
  12  * system, or to circumvent, violate, or enable the circumvention or
  13  * violation of, any terms of an Apple operating system software license
  14  * agreement.
  15  *
  16  * Please obtain a copy of the License at
  17  * http://www.opensource.apple.com/apsl/ and read it before using this
  18  * file.
  19  *
  20  * The Original Code and all software distributed under the License are
  21  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  22  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  23  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  24  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  25  * Please see the License for the specific language governing rights and
  26  * limitations under the License.
  27  *
  28  * @APPLE_LICENSE_OSREFERENCE_HEADER_END@
  29  */
  30 /* Copyright (c) 1992, 1997-1998 Apple Computer, Inc.  All rights reserved.
  31  *
  32  *      File:  machdep/ppc/libc/ffs.s
  33  *
  34  *      int ffs(int value)
  35  *
  36  *      DESCRIPTION
  37  *              The ffs() function finds the first bit set in value and returns the
  38  *              index of that bit.  Bits are numbered starting from 1, starting at
  39  *              the right-most bit. A return value of 0 means that the argument was
  40  *
  41  * HISTORY
  42  *      14-Aug-1998     Umesh Vaishampayan      (umeshv@apple.com)
  43  *              Optimized!
  44  *
  45  *  10-Mar-1998 Matt Watson (mwatson@apple.com)
  46  *      Correctified
  47  *
  48  *  19-Jan-1998 Matt Watson (mwatson@apple.com)
  49  *      Simplified
  50  *
  51  *  24-Jan-1997 Umesh Vaishampayan (umeshv@NeXT.com)
  52  *      Ported to PPC.
  53  */
  54
  55 .text
  56 .align 4
  57 .globl _ffs
  58 _ffs:                                   /* Cycles */
  59         neg             r0,r3           /* 0 */
  60         and             r3,r0,r3        /* 1 */
  61         li              r4, 32          /* 1 */
  62         cntlzw  r3,r3           /* 2 */
  63         subf    r3,r3,r4        /* 3 */
  64         blr
  65
  66         .globl  _abs
  67 _abs:
  68         srawi r0,r3,31
  69         xor r3,r0,r3
  70         subf r3,r0,r3
  71         blr
  72