lib/libm/src/s_modff.c

   1 /* s_modff.c -- float version of s_modf.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: s_modff.c,v 1.7 2002/05/26 22:01:57 wiz Exp $
  16  * $DragonFly: src/lib/libm/src/s_modff.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 one = 1.0;
  23
  24 float
  25 modff(float x, float *iptr)
  26 {
  27         int32_t i0,j0_;
  28         u_int32_t i;
  29         GET_FLOAT_WORD(i0,x);
  30         j0_ = ((i0>>23)&0xff)-0x7f;     /* exponent of x */
  31         if(j0_<23) {                    /* integer part in x */
  32             if(j0_<0) {                 /* |x|<1 */
  33                 SET_FLOAT_WORD(*iptr,i0&0x80000000);    /* *iptr = +-0 */
  34                 return x;
  35             } else {
  36                 i = (0x007fffff)>>j0_;
  37                 if((i0&i)==0) {                 /* x is integral */
  38                     u_int32_t ix;
  39                     *iptr = x;
  40                     GET_FLOAT_WORD(ix,x);
  41                     SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
  42                     return x;
  43                 } else {
  44                     SET_FLOAT_WORD(*iptr,i0&(~i));
  45                     return x - *iptr;
  46                 }
  47             }
  48         } else {                        /* no fraction part */
  49             u_int32_t ix;
  50             *iptr = x*one;
  51             GET_FLOAT_WORD(ix,x);
  52             SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
  53             return x;
  54         }
  55 }