sysdeps/ieee754/ldbl-128/s_floorl.c

   1 /* s_floorl.c -- long double version of s_floor.c.
   2  */
   3
   4 /*
   5  * ====================================================
   6  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   7  *
   8  * Developed at SunPro, a Sun Microsystems, Inc. business.
   9  * Permission to use, copy, modify, and distribute this
  10  * software is freely granted, provided that this notice
  11  * is preserved.
  12  * ====================================================
  13  */
  14
  15 #if defined(LIBM_SCCS) && !defined(lint)
  16 static char rcsid[] = "$NetBSD: $";
  17 #endif
  18
  19 /*
  20  * floorl(x)
  21  * Return x rounded toward -inf to integral value
  22  * Method:
  23  *      Bit twiddling.
  24  */
  25
  26 #define NO_MATH_REDIRECT
  27 #include <math.h>
  28 #include <math_private.h>
  29 #include <libm-alias-ldouble.h>
  30 #include <math-use-builtins.h>
  31
  32 _Float128
  33 __floorl (_Float128 x)
  34 {
  35 #if USE_FLOORL_BUILTIN
  36   return __builtin_floorl (x);
  37 #else
  38   /* Use generic implementation.  */
  39   int64_t i0, i1, j0;
  40   uint64_t i, j;
  41   GET_LDOUBLE_WORDS64 (i0, i1, x);
  42   j0 = ((i0 >> 48) & 0x7fff) - 0x3fff;
  43   if (j0 < 48)
  44     {
  45       if (j0 < 0)
  46         {
  47           /* return 0 * sign (x) if |x| < 1 */
  48           if (i0 >= 0)
  49             {
  50               i0 = i1 = 0;
  51             }
  52           else if (((i0 & 0x7fffffffffffffffLL) | i1) != 0)
  53             {
  54               i0 = 0xbfff000000000000ULL;
  55               i1 = 0;
  56             }
  57         }
  58       else
  59         {
  60           i = (0x0000ffffffffffffULL) >> j0;
  61           if (((i0 & i) | i1) == 0)
  62             return x;           /* x is integral  */
  63           if (i0 < 0)
  64             i0 += (0x0001000000000000LL) >> j0;
  65           i0 &= (~i);
  66           i1 = 0;
  67         }
  68     }
  69   else if (j0 > 111)
  70     {
  71       if (j0 == 0x4000)
  72         return x + x;           /* inf or NaN  */
  73       else
  74         return x;               /* x is integral  */
  75     }
  76   else
  77     {
  78       i = -1ULL >> (j0 - 48);
  79       if ((i1 & i) == 0)
  80         return x;               /* x is integral  */
  81       if (i0 < 0)
  82         {
  83           if (j0 == 48)
  84             i0 += 1;
  85           else
  86             {
  87               j = i1 + (1LL << (112 - j0));
  88               if (j < i1)
  89                 i0 += 1 ;       /* got a carry */
  90               i1 = j;
  91             }
  92         }
  93       i1 &= (~i);
  94     }
  95   SET_LDOUBLE_WORDS64 (x, i0, i1);
  96   return x;
  97 #endif /* ! USE_FLOORL_BUILTIN  */
  98 }
  99 libm_alias_ldouble (__floor, floor)