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 "math.h"
  17 #include "math_private.h"
  18
  19 static const float one = 1.0;
  20
  21 float
  22 modff(float x, float *iptr)
  23 {
  24         int32_t i0,jj0;
  25         u_int32_t i;
  26         GET_FLOAT_WORD(i0,x);
  27         jj0 = ((i0>>23)&0xff)-0x7f;     /* exponent of x */
  28         if(jj0<23) {                    /* integer part in x */
  29             if(jj0<0) {                 /* |x|<1 */
  30                 SET_FLOAT_WORD(*iptr,i0&0x80000000);    /* *iptr = +-0 */
  31                 return x;
  32             } else {
  33                 i = (0x007fffff)>>jj0;
  34                 if((i0&i)==0) {                 /* x is integral */
  35                     u_int32_t ix;
  36                     *iptr = x;
  37                     GET_FLOAT_WORD(ix,x);
  38                     SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
  39                     return x;
  40                 } else {
  41                     SET_FLOAT_WORD(*iptr,i0&(~i));
  42                     return x - *iptr;
  43                 }
  44             }
  45         } else {                        /* no fraction part */
  46             u_int32_t ix;
  47             *iptr = x*one;
  48             GET_FLOAT_WORD(ix,x);
  49             SET_FLOAT_WORD(x,ix&0x80000000);    /* return +-0 */
  50             return x;
  51         }
  52 }