lib/libm/src/e_remainderf.c

   1 /* e_remainderf.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  * $NetBSD: e_remainderf.c,v 1.7 2002/05/26 22:01:52 wiz Exp $
  16  * $DragonFly: src/lib/libm/src/e_remainderf.c,v 1.1 2005/07/26 21:15:20 joerg Exp $
  17  */
  18
  19 #include <math.h>
  20 #include "math_private.h"
  21
  22 static const float zero = 0.0;
  23
  24
  25 float
  26 remainderf(float x, float p)
  27 {
  28         int32_t hx,hp;
  29         u_int32_t sx;
  30         float p_half;
  31
  32         GET_FLOAT_WORD(hx,x);
  33         GET_FLOAT_WORD(hp,p);
  34         sx = hx&0x80000000;
  35         hp &= 0x7fffffff;
  36         hx &= 0x7fffffff;
  37
  38     /* purge off exception values */
  39         if(hp==0) return (x*p)/(x*p);           /* p = 0 */
  40         if((hx>=0x7f800000)||                   /* x not finite */
  41           ((hp>0x7f800000)))                    /* p is NaN */
  42             return (x*p)/(x*p);
  43
  44
  45         if (hp<=0x7effffff) x = fmodf(x,p+p);   /* now x < 2p */
  46         if ((hx-hp)==0) return zero*x;
  47         x  = fabsf(x);
  48         p  = fabsf(p);
  49         if (hp<0x01000000) {
  50             if(x+x>p) {
  51                 x-=p;
  52                 if(x+x>=p) x -= p;
  53             }
  54         } else {
  55             p_half = (float)0.5*p;
  56             if(x>p_half) {
  57                 x-=p;
  58                 if(x>=p_half) x -= p;
  59             }
  60         }
  61         GET_FLOAT_WORD(hx,x);
  62         SET_FLOAT_WORD(x,hx^sx);
  63         return x;
  64 }