bsd/dev/ppc/ffs.s

   1 /*
   2  * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
   3  *
   4  * @APPLE_LICENSE_HEADER_START@
   5  *
   6  * The contents of this file constitute Original Code as defined in and
   7  * are subject to the Apple Public Source License Version 1.1 (the
   8  * "License").  You may not use this file except in compliance with the
   9  * License.  Please obtain a copy of the License at
  10  * http://www.apple.com/publicsource and read it before using this file.
  11  *
  12  * This Original Code and all software distributed under the License are
  13  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  14  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  15  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  16  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
  17  * License for the specific language governing rights and limitations
  18  * under the License.
  19  *
  20  * @APPLE_LICENSE_HEADER_END@
  21  */
  22 /* Copyright (c) 1992, 1997-1998 Apple Computer, Inc.  All rights reserved.
  23  *
  24  *      File:  machdep/ppc/libc/ffs.s
  25  *
  26  *      int ffs(int value)
  27  *
  28  *      DESCRIPTION
  29  *              The ffs() function finds the first bit set in value and returns the
  30  *              index of that bit.  Bits are numbered starting from 1, starting at
  31  *              the right-most bit. A return value of 0 means that the argument was
  32  *
  33  * HISTORY
  34  *      14-Aug-1998     Umesh Vaishampayan      (umeshv@apple.com)
  35  *              Optimized!
  36  *
  37  *  10-Mar-1998 Matt Watson (mwatson@apple.com)
  38  *      Correctified
  39  *
  40  *  19-Jan-1998 Matt Watson (mwatson@apple.com)
  41  *      Simplified
  42  *
  43  *  24-Jan-1997 Umesh Vaishampayan (umeshv@NeXT.com)
  44  *      Ported to PPC.
  45  */
  46
  47 .text
  48 .align 4
  49 .globl _ffs
  50 _ffs:                                   /* Cycles */
  51         neg             r0,r3           /* 0 */
  52         and             r3,r0,r3        /* 1 */
  53         li              r4, 32          /* 1 */
  54         cntlzw  r3,r3           /* 2 */
  55         subf    r3,r3,r4        /* 3 */
  56         blr
  57
  58         .globl  _abs
  59 _abs:
  60         srawi r0,r3,31
  61         xor r3,r0,r3
  62         subf r3,r0,r3
  63         blr
  64