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
  16 #include <sys/cdefs.h>
  17 #if defined(LIBM_SCCS) && !defined(lint)
  18 __RCSID("$NetBSD: s_modff.c,v 1.9 2010/01/27 14:07:41 drochner Exp $");
  19 #endif
  20
  21 #include "math.h"
  22 #include "math_private.h"
  23
  24 static const float one = 1.0;
  25
  26 float
  27 modff(float x, float *iptr)
  28 {
  29         int32_t i0,jj0;
  30         u_int32_t i;
  31         GET_FLOAT_WORD(i0,x);
  32         jj0 = ((i0>>23)&0xff)-0x7f;     /* exponent of x */
  33         if(jj0<23) {                    /* integer part in x */
  34             if(jj0<0) {                 /* |x|<1 */
  35                 SET_FLOAT_WORD(*iptr,i0&0x80000000);    /* *iptr = +-0 */
  36                 return x;
  37             } else {
  38                 i = (0x007fffff)>>jj0;
  39                 if((i0&i)==0) {                 /* x is integral */
  40                     u_int32_t ix;
  41                     *iptr = x;
  42                     GET_FLOAT_WORD(ix,x);
  43                     SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
  44                     return x;
  45                 } else {
  46                     SET_FLOAT_WORD(*iptr,i0&(~i));
  47                     return x - *iptr;
  48                 }
  49             }
  50         } else {                        /* no fraction part */
  51             u_int32_t ix;
  52             *iptr = x*one;
  53             if (jj0 == 0x80)            /* +-inf or NaN */
  54                 return 0.0 / x;         /* +-0 or NaN */
  55             GET_FLOAT_WORD(ix,x);
  56             SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
  57             return x;
  58         }
  59 }