sysdeps/ieee754/flt-32/s_floorf.c

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