compiler/stdc/math/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
  16 #ifndef lint
  17 static char rcsid[] = "$FreeBSD: src/lib/msun/src/s_modff.c,v 1.8 2007/01/06 21:22:57 das Exp $";
  18 #endif
  19
  20 #include "math.h"
  21 #include "math_private.h"
  22
  23 static const float one = 1.0;
  24
  25 float
  26 modff(float x, float *iptr)
  27 {
  28         int32_t i0,j0;
  29         uint32_t i;
  30         GET_FLOAT_WORD(i0,x);
  31         j0 = ((i0>>23)&0xff)-0x7f;      /* exponent of x */
  32         if(j0<23) {                     /* integer part in x */
  33             if(j0<0) {                  /* |x|<1 */
  34                 SET_FLOAT_WORD(*iptr,i0&0x80000000);    /* *iptr = +-0 */
  35                 return x;
  36             } else {
  37                 i = (0x007fffff)>>j0;
  38                 if((i0&i)==0) {                 /* x is integral */
  39                     uint32_t ix;
  40                     *iptr = x;
  41                     GET_FLOAT_WORD(ix,x);
  42                     SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
  43                     return x;
  44                 } else {
  45                     SET_FLOAT_WORD(*iptr,i0&(~i));
  46                     return x - *iptr;
  47                 }
  48             }
  49         } else {                        /* no fraction part */
  50             uint32_t ix;
  51             *iptr = x*one;
  52             if (x != x)                 /* NaN */
  53                 return x;
  54             GET_FLOAT_WORD(ix,x);
  55             SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
  56             return x;
  57         }
  58 }