sysdeps/libm-ieee754/s_ceill.c

   1 /* s_ceill.c -- long double version of s_ceil.c.
   2  * Conversion to long double by Ulrich Drepper,
   3  * Cygnus Support, drepper@cygnus.com.
   4  */
   5
   6 /*
   7  * ====================================================
   8  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   9  *
  10  * Developed at SunPro, a Sun Microsystems, Inc. business.
  11  * Permission to use, copy, modify, and distribute this
  12  * software is freely granted, provided that this notice
  13  * is preserved.
  14  * ====================================================
  15  */
  16
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 static char rcsid[] = "$NetBSD: $";
  19 #endif
  20
  21 /*
  22  * ceill(x)
  23  * Return x rounded toward -inf to integral value
  24  * Method:
  25  *      Bit twiddling.
  26  * Exception:
  27  *      Inexact flag raised if x not equal to ceil(x).
  28  */
  29
  30 #include "math.h"
  31 #include "math_private.h"
  32
  33 #ifdef __STDC__
  34 static const long double huge = 1.0e4930;
  35 #else
  36 static long double huge = 1.0e4930;
  37 #endif
  38
  39 #ifdef __STDC__
  40         long double __ceill(long double x)
  41 #else
  42         long double __ceill(x)
  43         long double x;
  44 #endif
  45 {
  46         int32_t i1,j0;
  47         u_int32_t i,j,se,i0,sx;
  48         GET_LDOUBLE_WORDS(se,i0,i1,x);
  49         sx = (se>>15)&1;
  50         j0 = (se&0x7fff)-0x3fff;
  51         if(j0<31) {
  52             if(j0<0) {  /* raise inexact if x != 0 */
  53                 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
  54                     if(sx) {se=0x8000;i0=0;i1=0;}
  55                     else if((i0|i1)!=0) { se=0x3fff;i0=0;i1=0;}
  56                 }
  57             } else {
  58                 i = (0x7fffffff)>>j0;
  59                 if(((i0&i)|i1)==0) return x; /* x is integral */
  60                 if(huge+x>0.0) {        /* raise inexact flag */
  61                     if(sx==0) {
  62                         if (j0>0) i0 += (0x80000000)>>j0;
  63                         else ++se;
  64                     }
  65                     i0 &= (~i); i1=0;
  66                 }
  67             }
  68         } else if (j0>62) {
  69             if(j0==0x4000) return x+x;  /* inf or NaN */
  70             else return x;              /* x is integral */
  71         } else {
  72             i = ((u_int32_t)(0xffffffff))>>(j0-31);
  73             if((i1&i)==0) return x;     /* x is integral */
  74             if(huge+x>0.0) {            /* raise inexact flag */
  75                 if(sx==0) {
  76                     if(j0==31) i0+=1;
  77                     else {
  78                         j = i1 + (1<<(63-j0));
  79                         if(j<i1) i0+=1; /* got a carry */
  80                         i1 = j;
  81                     }
  82                 }
  83                 i1 &= (~i);
  84             }
  85         }
  86         SET_LDOUBLE_WORDS(x,se,i0,i1);
  87         return x;
  88 }
  89 weak_alias (__ceill, ceill)