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  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) */
  81.