sysdeps/ieee754/ldbl-96/s_floorl.c

   1 /* s_floorl.c -- long double version of s_floor.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  * floorl(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 floor(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 __floorl(long double x)
  41 #else
  42         long double __floorl(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==0) {se=0;i0=i1=0;}
  55                     else if(((se&0x7fff)|i0|i1)!=0)
  56                         { se=0xbfff;i0=i1=0;}
  57                 }
  58             } else {
  59                 i = (0x7fffffff)>>j0;
  60                 if(((i0&i)|i1)==0) return x; /* x is integral */
  61                 if(huge+x>0.0) {        /* raise inexact flag */
  62                     if(sx) {
  63                         if (j0>0 && (i0+(0x80000000>>j0))>i0)
  64                           i0 += (0x80000000)>>j0;
  65                         else
  66                           {
  67                             i = 0x7fffffff;
  68                             ++se;
  69                           }
  70                     }
  71                     i0 &= (~i); i1=0;
  72                 }
  73             }
  74         } else if (j0>62) {
  75             if(j0==0x4000) return x+x;  /* inf or NaN */
  76             else return x;              /* x is integral */
  77         } else {
  78             i = ((u_int32_t)(0xffffffff))>>(j0-31);
  79             if((i1&i)==0) return x;     /* x is integral */
  80             if(huge+x>0.0) {            /* raise inexact flag */
  81                 if(sx) {
  82                     if(j0==31) i0+=1;
  83                     else {
  84                         j = i1+(1<<(63-j0));
  85                         if(j<i1) i0 +=1 ;       /* got a carry */
  86                         i1=j;
  87                     }
  88                 }
  89                 i1 &= (~i);
  90             }
  91         }
  92         SET_LDOUBLE_WORDS(x,se,i0,i1);
  93         return x;
  94 }
  95 weak_alias (__floorl, floorl)