sysdeps/ieee754/flt-32/s_floorf.c

   1 /* s_floorf.c -- float 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 /*
  16  * floorf(x)
  17  * Return x rounded toward -inf to integral value
  18  * Method:
  19  *      Bit twiddling.
  20  */
  21
  22 #define NO_MATH_REDIRECT
  23 #include <math.h>
  24 #include <math_private.h>
  25 #include <libm-alias-float.h>
  26 #include <math-use-builtins.h>
  27
  28 float
  29 __floorf (float x)
  30 {
  31 #if USE_FLOORF_BUILTIN
  32   return __builtin_floorf (x);
  33 #else
  34   /* Use generic implementation.  */
  35   int32_t i0, j0;
  36   uint32_t i;
  37   GET_FLOAT_WORD (i0, x);
  38   j0 = ((i0 >> 23) & 0xff) - 0x7f;
  39   if (j0 < 23)
  40     {
  41       if (j0 < 0)
  42         {
  43           /* return 0 * sign (x) if |x| < 1  */
  44           if (i0 >= 0)
  45             i0 = 0;
  46           else if ((i0 & 0x7fffffff) != 0)
  47             i0 = 0xbf800000;
  48         }
  49       else
  50         {
  51           i = (0x007fffff) >> j0;
  52           if ((i0 & i) == 0)
  53             return x;           /* x is integral  */
  54           if (i0 < 0)
  55             i0 += (0x00800000) >> j0;
  56           i0 &= (~i);
  57         }
  58     }
  59   else
  60     {
  61       if (__glibc_unlikely (j0 == 0x80))
  62         return x + x;           /* inf or NaN  */
  63       else
  64         return x;               /* x is integral  */
  65     }
  66   SET_FLOAT_WORD (x, i0);
  67   return x;
  68 #endif /* ! USE_FLOORF_BUILTIN  */
  69 }
  70 #ifndef __floorf
  71 libm_alias_float (__floor, floor)
  72 #endif