newlib/libm/mathfp/ef_remainder.c

   1 /* ef_remainder.c -- float version of e_remainder.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 #include "fdlibm.h"
  17
  18 #ifdef __STDC__
  19 static const float zero = 0.0;
  20 #else
  21 static float zero = 0.0;
  22 #endif
  23
  24
  25 #ifdef __STDC__
  26         float remainderf(float x, float p)
  27 #else
  28         float remainderf(x,p)
  29         float x,p;
  30 #endif
  31 {
  32         __int32_t hx,hp;
  33         __uint32_t sx;
  34         float p_half;
  35
  36         GET_FLOAT_WORD(hx,x);
  37         GET_FLOAT_WORD(hp,p);
  38         sx = hx&0x80000000;
  39         hp &= 0x7fffffff;
  40         hx &= 0x7fffffff;
  41
  42     /* purge off exception values */
  43         if(hp==0) return (x*p)/(x*p);           /* p = 0 */
  44         if((hx>=0x7f800000)||                   /* x not finite */
  45           ((hp>0x7f800000)))                    /* p is NaN */
  46             return (x*p)/(x*p);
  47
  48
  49         if (hp<=0x7effffff) x = fmodf(x,p+p);   /* now x < 2p */
  50         if ((hx-hp)==0) return zero*x;
  51         x  = fabsf(x);
  52         p  = fabsf(p);
  53         if (hp<0x01000000) {
  54             if(x+x>p) {
  55                 x-=p;
  56                 if(x+x>=p) x -= p;
  57             }
  58         } else {
  59             p_half = (float)0.5*p;
  60             if(x>p_half) {
  61                 x-=p;
  62                 if(x>=p_half) x -= p;
  63             }
  64         }
  65         GET_FLOAT_WORD(hx,x);
  66         SET_FLOAT_WORD(x,hx^sx);
  67         return x;
  68 }