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
  16 #include <sys/cdefs.h>
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: e_remainderf.c,v 1.7 2002/05/26 22:01:52 wiz Exp $");
  19 #endif
  20
  21 #include "math.h"
  22 #include "math_private.h"
  23
  24 static const float zero = 0.0;
  25
  26
  27 float
  28 __ieee754_remainderf(float x, float p)
  29 {
  30         int32_t hx,hp;
  31         u_int32_t sx;
  32         float p_half;
  33
  34         GET_FLOAT_WORD(hx,x);
  35         GET_FLOAT_WORD(hp,p);
  36         sx = hx&0x80000000;
  37         hp &= 0x7fffffff;
  38         hx &= 0x7fffffff;
  39
  40     /* purge off exception values */
  41         if(hp==0) return (x*p)/(x*p);           /* p = 0 */
  42         if((hx>=0x7f800000)||                   /* x not finite */
  43           ((hp>0x7f800000)))                    /* p is NaN */
  44             return (x*p)/(x*p);
  45
  46
  47         if (hp<=0x7effffff) x = __ieee754_fmodf(x,p+p); /* now x < 2p */
  48         if ((hx-hp)==0) return zero*x;
  49         x  = fabsf(x);
  50         p  = fabsf(p);
  51         if (hp<0x01000000) {
  52             if(x+x>p) {
  53                 x-=p;
  54                 if(x+x>=p) x -= p;
  55             }
  56         } else {
  57             p_half = (float)0.5*p;
  58             if(x>p_half) {
  59                 x-=p;
  60                 if(x>=p_half) x -= p;
  61             }
  62         }
  63         GET_FLOAT_WORD(hx,x);
  64         SET_FLOAT_WORD(x,hx^sx);
  65         return x;
  66 }