toolchain/gcc/newlib/libm/math/sf_floor.c

   1 /* sf_floor.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  * Exception:
  22  *      Inexact flag raised if x not equal to floorf(x).
  23  */
  24
  25 #include "fdlibm.h"
  26
  27 #ifdef __STDC__
  28 static const float huge = 1.0e30;
  29 #else
  30 static float huge = 1.0e30;
  31 #endif
  32
  33 #ifdef __STDC__
  34         float floorf(float x)
  35 #else
  36         float floorf(x)
  37         float x;
  38 #endif
  39 {
  40         __int32_t i0,j0;
  41         __uint32_t i,ix;
  42         GET_FLOAT_WORD(i0,x);
  43         ix = (i0&0x7fffffff);
  44         j0 = (ix>>23)-0x7f;
  45         if(j0<23) {
  46             if(j0<0) {  /* raise inexact if x != 0 */
  47                 if(huge+x>(float)0.0) {/* return 0*sign(x) if |x|<1 */
  48                     if(i0>=0) {i0=0;}
  49                     else if(!FLT_UWORD_IS_ZERO(ix))
  50                         { i0=0xbf800000;}
  51                 }
  52             } else {
  53                 i = (0x007fffff)>>j0;
  54                 if((i0&i)==0) return x; /* x is integral */
  55                 if(huge+x>(float)0.0) { /* raise inexact flag */
  56                     if(i0<0) i0 += (0x00800000)>>j0;
  57                     i0 &= (~i);
  58                 }
  59             }
  60         } else {
  61             if(!FLT_UWORD_IS_FINITE(ix)) return x+x;    /* inf or NaN */
  62             else return x;              /* x is integral */
  63         }
  64         SET_FLOAT_WORD(x,i0);
  65         return x;
  66 }
  67
  68 #ifdef _DOUBLE_IS_32BITS
  69
  70 #ifdef __STDC__
  71         double floor(double x)
  72 #else
  73         double floor(x)
  74         double x;
  75 #endif
  76 {
  77         return (double) floorf((float) x);
  78 }
  79
  80 #endif /* defined(_DOUBLE_IS_32BITS) */