lib/libm/noieee_src/n_floor.c

   1 /*      $NetBSD: n_floor.c,v 1.5 2003/08/07 16:44:51 agc Exp $ */
   2 /*
   3  * Copyright (c) 1985, 1993
   4  *      The Regents of the University of California.  All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  * 1. Redistributions of source code must retain the above copyright
  10  *    notice, this list of conditions and the following disclaimer.
  11  * 2. Redistributions in binary form must reproduce the above copyright
  12  *    notice, this list of conditions and the following disclaimer in the
  13  *    documentation and/or other materials provided with the distribution.
  14  * 3. Neither the name of the University nor the names of its contributors
  15  *    may be used to endorse or promote products derived from this software
  16  *    without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  19  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  20  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  21  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  22  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  23  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  24  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  26  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  27  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  28  * SUCH DAMAGE.
  29  */
  30
  31 #ifndef lint
  32 #if 0
  33 static char sccsid[] = "@(#)floor.c     8.1 (Berkeley) 6/4/93";
  34 #endif
  35 #endif /* not lint */
  36
  37 #define _LIBM_STATIC
  38 #include "mathimpl.h"
  39
  40 vc(L, 4503599627370496.0E0 ,0000,5c00,0000,0000, 55, 1.0) /* 2**55 */
  41
  42 ic(L, 4503599627370496.0E0, 52, 1.0)                      /* 2**52 */
  43
  44 #ifdef vccast
  45 #define L       vccast(L)
  46 #endif
  47
  48 /*
  49  * floor(x) := the largest integer no larger than x;
  50  * ceil(x) := -floor(-x), for all real x.
  51  *
  52  * Note: Inexact will be signaled if x is not an integer, as is
  53  *      customary for IEEE 754.  No other signal can be emitted.
  54  */
  55 double
  56 floor(double x)
  57 {
  58         volatile double y;
  59
  60         if (
  61 #if !defined(__vax__)&&!defined(tahoe)
  62                 x != x ||       /* NaN */
  63 #endif  /* !defined(__vax__)&&!defined(tahoe) */
  64                 x >= L)         /* already an even integer */
  65                 return x;
  66         else if (x < (double)0)
  67                 return -ceil(-x);
  68         else {                  /* now 0 <= x < L */
  69                 y = L+x;                /* destructive store must be forced */
  70                 y -= L;                 /* an integer, and |x-y| < 1 */
  71                 return x < y ? y-(double)1 : y;
  72         }
  73 }
  74
  75 float
  76 floorf(float x)
  77 {
  78         return floor((double)x);
  79 }
  80
  81 double
  82 ceil(double x)
  83 {
  84         volatile double y;
  85
  86         if (
  87 #if !defined(__vax__)&&!defined(tahoe)
  88                 x != x ||       /* NaN */
  89 #endif  /* !defined(__vax__)&&!defined(tahoe) */
  90                 x >= L)         /* already an even integer */
  91                 return x;
  92         else if (x < (double)0)
  93                 return -floor(-x);
  94         else {                  /* now 0 <= x < L */
  95                 y = L+x;                /* destructive store must be forced */
  96                 y -= L;                 /* an integer, and |x-y| < 1 */
  97                 return x > y ? y+(double)1 : y;
  98         }
  99 }
 100
 101 float
 102 ceilf(float x)
 103 {
 104         return ceil((double)x);
 105 }
 106
 107 #ifndef ns32000                 /* rint() is in ./NATIONAL/support.s */
 108 /*
 109  * algorithm for rint(x) in pseudo-pascal form ...
 110  *
 111  * real rint(x): real x;
 112  *      ... delivers integer nearest x in direction of prevailing rounding
 113  *      ... mode
 114  * const        L = (last consecutive integer)/2
 115  *        = 2**55; for VAX D
 116  *        = 2**52; for IEEE 754 Double
 117  * real s,t;
 118  * begin
 119  *      if x != x then return x;                ... NaN
 120  *      if |x| >= L then return x;              ... already an integer
 121  *      s := copysign(L,x);
 122  *      t := x + s;                             ... = (x+s) rounded to integer
 123  *      return t - s
 124  * end;
 125  *
 126  * Note: Inexact will be signaled if x is not an integer, as is
 127  *      customary for IEEE 754.  No other signal can be emitted.
 128  */
 129 double
 130 rint(double x)
 131 {
 132         double s;
 133         volatile double t;
 134         const double one = 1.0;
 135
 136 #if !defined(__vax__)&&!defined(tahoe)
 137         if (x != x)                             /* NaN */
 138                 return (x);
 139 #endif  /* !defined(__vax__)&&!defined(tahoe) */
 140         if (copysign(x,one) >= L)               /* already an integer */
 141             return (x);
 142         s = copysign(L,x);
 143         t = x + s;                              /* x+s rounded to integer */
 144         return (t - s);
 145 }
 146 #endif  /* not national */