libquadmath/math/floorq.c

   1 /* floorq.c -- __float128 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 #include "quadmath-imp.h"
  17
  18 static const __float128 huge = 1.0e4930Q;
  19
  20 __float128
  21 floorq (__float128 x)
  22 {
  23         int64_t i0,i1,j0;
  24         uint64_t i,j;
  25         GET_FLT128_WORDS64(i0,i1,x);
  26         j0 = ((i0>>48)&0x7fff)-0x3fff;
  27         if(j0<48) {
  28             if(j0<0) {  /* raise inexact if x != 0 */
  29                 if(huge+x>0.0) {/* return 0*sign(x) if |x|<1 */
  30                     if(i0>=0) {i0=i1=0;}
  31                     else if(((i0&0x7fffffffffffffffLL)|i1)!=0)
  32                         { i0=0xbfff000000000000ULL;i1=0;}
  33                 }
  34             } else {
  35                 i = (0x0000ffffffffffffULL)>>j0;
  36                 if(((i0&i)|i1)==0) return x; /* x is integral */
  37                 if(huge+x>0.0) {        /* raise inexact flag */
  38                     if(i0<0) i0 += (0x0001000000000000LL)>>j0;
  39                     i0 &= (~i); i1=0;
  40                 }
  41             }
  42         } else if (j0>111) {
  43             if(j0==0x4000) return x+x;  /* inf or NaN */
  44             else return x;              /* x is integral */
  45         } else {
  46             i = -1ULL>>(j0-48);
  47             if((i1&i)==0) return x;     /* x is integral */
  48             if(huge+x>0.0) {            /* raise inexact flag */
  49                 if(i0<0) {
  50                     if(j0==48) i0+=1;
  51                     else {
  52                         j = i1+(1LL<<(112-j0));
  53                         if(j<i1) i0 +=1 ;       /* got a carry */
  54                         i1=j;
  55                     }
  56                 }
  57                 i1 &= (~i);
  58             }
  59         }
  60         SET_FLT128_WORDS64(x,i0,i1);
  61         return x;
  62 }