libquadmath/math/floorq.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  * floorq(x)
  22  * Return x rounded toward -inf to integral value
  23  * Method:
  24  *      Bit twiddling.
  25  */
  26
  27 #define NO_MATH_REDIRECT
  28
  29 #include "quadmath-imp.h"
  30
  31 __float128 floorq(__float128 x)
  32 {
  33         int64_t i0,i1,j0;
  34         uint64_t i,j;
  35         GET_FLT128_WORDS64(i0,i1,x);
  36         j0 = ((i0>>48)&0x7fff)-0x3fff;
  37         if(j0<48) {
  38             if(j0<0) {
  39                 /* return 0*sign(x) if |x|<1 */
  40                 if(i0>=0) {i0=i1=0;}
  41                 else if(((i0&0x7fffffffffffffffLL)|i1)!=0)
  42                     { i0=0xbfff000000000000ULL;i1=0;}
  43             } else {
  44                 i = (0x0000ffffffffffffULL)>>j0;
  45                 if(((i0&i)|i1)==0) return x; /* x is integral */
  46                 if(i0<0) i0 += (0x0001000000000000LL)>>j0;
  47                 i0 &= (~i); i1=0;
  48             }
  49         } else if (j0>111) {
  50             if(j0==0x4000) return x+x;  /* inf or NaN */
  51             else return x;              /* x is integral */
  52         } else {
  53             i = -1ULL>>(j0-48);
  54             if((i1&i)==0) return x;     /* x is integral */
  55             if(i0<0) {
  56                 if(j0==48) i0+=1;
  57                 else {
  58                     j = i1+(1LL<<(112-j0));
  59                     if(j<i1) i0 +=1 ;   /* got a carry */
  60                     i1=j;
  61                 }
  62             }
  63             i1 &= (~i);
  64         }
  65         SET_FLT128_WORDS64(x,i0,i1);
  66         return x;
  67 }