5261 libm should stop using synonyms.h
5298 fabs is 0-sized, confuses dis(1) and others
Reviewed by: Josef 'Jeff' Sipek <jeffpc@josefsipek.net>
Approved by: Gordon Ross <gwr@nexenta.com>

          --- old/usr/src/lib/libm/common/C/fmod.c
          +++ new/usr/src/lib/libm/common/C/fmod.c

   1    1  /*
   2    2   * CDDL HEADER START
   3    3   *
   4    4   * The contents of this file are subject to the terms of the
   5    5   * Common Development and Distribution License (the "License").
   6    6   * You may not use this file except in compliance with the License.
   7    7   *
   8    8   * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9    9   * or http://www.opensolaris.org/os/licensing.
  10   10   * See the License for the specific language governing permissions
  11   11   * and limitations under the License.
  12   12   *
  13   13   * When distributing Covered Code, include this CDDL HEADER in each
  14   14   * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15   15   * If applicable, add the following below this CDDL HEADER, with the
  16   16   * fields enclosed by brackets "[]" replaced with your own identifying
  17   17   * information: Portions Copyright [yyyy] [name of copyright owner]
  18   18   *

  19   19   * CDDL HEADER END
  20   20   */
  21   21  /*
  22   22   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
  23   23   */
  24   24  /*
  25   25   * Copyright 2006 Sun Microsystems, Inc.  All rights reserved.
  26   26   * Use is subject to license terms.
  27   27   */
  28   28  
  29      -#pragma weak fmod = __fmod
       29 +#pragma weak __fmod = fmod
  30   30  
  31   31  #include "libm.h"
  32   32  
  33   33  static const double zero = 0.0;
  34   34  
  35   35  /*
  36   36   * The following implementation assumes fast 64-bit integer arith-
  37   37   * metic.  This is fine for sparc because we build libm in v8plus
  38   38   * mode.  It's also fine for sparcv9 and amd64, although we have
  39   39   * assembly code on amd64.  For x86, it would be better to use

  40   40   * 32-bit code, but we have assembly for x86, too.
  41   41   */
  42   42  double
  43   43  fmod(double x, double y) {
  44   44          double          w;
  45   45          long long       hx, ix, iy, iz;
  46   46          int             nd, k, ny;
  47   47  
  48   48          hx = *(long long *)&x;
  49   49          ix = hx & ~0x8000000000000000ull;
  50   50          iy = *(long long *)&y & ~0x8000000000000000ull;
  51   51  
  52   52          /* handle special cases */
  53   53          if (iy == 0ll)
  54   54                  return (_SVID_libm_err(x, y, 27));
  55   55  
  56   56          if (ix >= 0x7ff0000000000000ll || iy > 0x7ff0000000000000ll)
  57   57                  return ((x * y) * zero);
  58   58  
  59   59          if (ix <= iy)
  60   60                  return ((ix < iy)? x : x * zero);
  61   61  
  62   62          /*
  63   63           * Set:
  64   64           *      ny = true exponent of y
  65   65           *      nd = true exponent of x minus true exponent of y
  66   66           *      ix = normalized significand of x
  67   67           *      iy = normalized significand of y
  68   68           */
  69   69          ny = iy >> 52;
  70   70          k = ix >> 52;
  71   71          if (ny == 0) {
  72   72                  /* y is subnormal, x could be normal or subnormal */
  73   73                  ny = 1;
  74   74                  while (iy < 0x0010000000000000ll) {
  75   75                          ny -= 1;
  76   76                          iy += iy;
  77   77                  }
  78   78                  nd = k - ny;
  79   79                  if (k == 0) {
  80   80                          nd += 1;
  81   81                          while (ix < 0x0010000000000000ll) {
  82   82                                  nd -= 1;
  83   83                                  ix += ix;
  84   84                          }
  85   85                  } else {
  86   86                          ix = 0x0010000000000000ll | (ix & 0x000fffffffffffffll);
  87   87                  }
  88   88          } else {
  89   89                  /* both x and y are normal */
  90   90                  nd = k - ny;
  91   91                  ix = 0x0010000000000000ll | (ix & 0x000fffffffffffffll);
  92   92                  iy = 0x0010000000000000ll | (iy & 0x000fffffffffffffll);
  93   93          }
  94   94  
  95   95          /* perform fixed point mod */
  96   96          while (nd--) {
  97   97                  iz = ix - iy;
  98   98                  if (iz >= 0)
  99   99                          ix = iz;
 100  100                  ix += ix;
 101  101          }
 102  102          iz = ix - iy;
 103  103          if (iz >= 0)
 104  104                  ix = iz;
 105  105  
 106  106          /* convert back to floating point and restore the sign */
 107  107          if (ix == 0ll)
 108  108                  return (x * zero);
 109  109          while (ix < 0x0010000000000000ll) {
 110  110                  ix += ix;
 111  111                  ny -= 1;
 112  112          }
 113  113          while (ix > 0x0020000000000000ll) {     /* XXX can this ever happen? */
 114  114                  ny += 1;
 115  115                  ix >>= 1;
 116  116          }
 117  117          if (ny <= 0) {
 118  118                  /* result is subnormal */
 119  119                  k = -ny + 1;
 120  120                  ix >>= k;
 121  121                  *(long long *)&w = (hx & 0x8000000000000000ull) | ix;
 122  122                  return (w);
 123  123          }
 124  124          *(long long *)&w = (hx & 0x8000000000000000ull) |
 125  125              ((long long)ny << 52) | (ix & 0x000fffffffffffffll);
 126  126          return (w);
 127  127  }

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