sysdeps/ieee754/ldbl-128/s_floorl.c

   1 /* s_floorl.c -- long double version of s_floor.c.
   2  * Conversion to IEEE quad long double by Jakub Jelinek, jj@ultra.linux.cz.
   3  */
   4
   5 /*
   6  * ====================================================
   7  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   8  *
   9  * Developed at SunPro, a Sun Microsystems, Inc. business.
  10  * Permission to use, copy, modify, and distribute this
  11  * software is freely granted, provided that this notice
  12  * is preserved.
  13  * ====================================================
  14  */
  15
  16 #if defined(LIBM_SCCS) && !defined(lint)
  17 static char rcsid[] = "$NetBSD: $";
  18 #endif
  19
  20 /*
  21  * floorl(x)
  22  * Return x rounded toward -inf to integral value
  23  * Method:
  24  *      Bit twiddling.
  25  * Exception:
  26  *      Inexact flag raised if x not equal to floor(x).
  27  */
  28
  29 #include <math.h>
  30 #include <math_private.h>
  31
  32 static const long double huge = 1.0e4930L;
  33
  34 long double __floorl(long double x)
  35 {
  36         int64_t i0,i1,j0;
  37         u_int64_t i,j;
  38         GET_LDOUBLE_WORDS64(i0,i1,x);
  39         j0 = ((i0>>48)&0x7fff)-0x3fff;
  40         if(j0<48) {
  41             if(j0<0) {  /* raise inexact if x != 0 */
  42                 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
  43                     if(i0>=0) {i0=i1=0;}
  44                     else if(((i0&0x7fffffffffffffffLL)|i1)!=0)
  45                         { i0=0xbfff000000000000ULL;i1=0;}
  46                 }
  47             } else {
  48                 i = (0x0000ffffffffffffULL)>>j0;
  49                 if(((i0&i)|i1)==0) return x; /* x is integral */
  50                 if(huge+x>0.0) {        /* raise inexact flag */
  51                     if(i0<0) i0 += (0x0001000000000000LL)>>j0;
  52                     i0 &= (~i); i1=0;
  53                 }
  54             }
  55         } else if (j0>111) {
  56             if(j0==0x4000) return x+x;  /* inf or NaN */
  57             else return x;              /* x is integral */
  58         } else {
  59             i = -1ULL>>(j0-48);
  60             if((i1&i)==0) return x;     /* x is integral */
  61             if(huge+x>0.0) {            /* raise inexact flag */
  62                 if(i0<0) {
  63                     if(j0==48) i0+=1;
  64                     else {
  65                         j = i1+(1LL<<(112-j0));
  66                         if(j<i1) i0 +=1 ;       /* got a carry */
  67                         i1=j;
  68                     }
  69                 }
  70                 i1 &= (~i);
  71             }
  72         }
  73         SET_LDOUBLE_WORDS64(x,i0,i1);
  74         return x;
  75 }
  76 weak_alias (__floorl, floorl)