toolchain/gcc/libjava/java/lang/s_ceil.c

   1
   2 /* @(#)s_ceil.c 5.1 93/09/24 */
   3 /*
   4  * ====================================================
   5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   6  *
   7  * Developed at SunPro, a Sun Microsystems, Inc. business.
   8  * Permission to use, copy, modify, and distribute this
   9  * software is freely granted, provided that this notice
  10  * is preserved.
  11  * ====================================================
  12  */
  13
  14 /*
  15  * ceil(x)
  16  * Return x rounded toward -inf to integral value
  17  * Method:
  18  *      Bit twiddling.
  19  * Exception:
  20  *      Inexact flag raised if x not equal to ceil(x).
  21  */
  22
  23 #include "fdlibm.h"
  24
  25 #ifndef _DOUBLE_IS_32BITS
  26
  27 #ifdef __STDC__
  28 static const double huge = 1.0e300;
  29 #else
  30 static double huge = 1.0e300;
  31 #endif
  32
  33 #ifdef __STDC__
  34         double ceil(double x)
  35 #else
  36         double ceil(x)
  37         double x;
  38 #endif
  39 {
  40         int32_t i0,i1,j0;
  41         uint32_t i,j;
  42         EXTRACT_WORDS(i0,i1,x);
  43         j0 = ((i0>>20)&0x7ff)-0x3ff;
  44         if(j0<20) {
  45             if(j0<0) {  /* raise inexact if x != 0 */
  46                 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
  47                     if(i0<0) {i0=0x80000000;i1=0;}
  48                     else if((i0|i1)!=0) { i0=0x3ff00000;i1=0;}
  49                 }
  50             } else {
  51                 i = (0x000fffff)>>j0;
  52                 if(((i0&i)|i1)==0) return x; /* x is integral */
  53                 if(huge+x>0.0) {        /* raise inexact flag */
  54                     if(i0>0) i0 += (0x00100000)>>j0;
  55                     i0 &= (~i); i1=0;
  56                 }
  57             }
  58         } else if (j0>51) {
  59             if(j0==0x400) return x+x;   /* inf or NaN */
  60             else return x;              /* x is integral */
  61         } else {
  62             i = ((uint32_t)(0xffffffff))>>(j0-20);
  63             if((i1&i)==0) return x;     /* x is integral */
  64             if(huge+x>0.0) {            /* raise inexact flag */
  65                 if(i0>0) {
  66                     if(j0==20) i0+=1;
  67                     else {
  68                         j = i1 + (1<<(52-j0));
  69                         if(j<(uint32_t)i1) i0+=1;       /* got a carry */
  70                         i1 = j;
  71                     }
  72                 }
  73                 i1 &= (~i);
  74             }
  75         }
  76         INSERT_WORDS(x,i0,i1);
  77         return x;
  78 }
  79
  80 #endif /* _DOUBLE_IS_32BITS */