toolchain/gcc/newlib/libm/math/s_ldexp.c

   1
   2 /* @(#)s_ldexp.c 5.1 93/09/24 */
   3 /*
   4  * ====================================================
   5  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   6  *
   7  * Developed at SunPro, a Sun Microsystems, Inc. business.
   8  * Permission to use, copy, modify, and distribute this
   9  * software is freely granted, provided that this notice
  10  * is preserved.
  11  * ====================================================
  12  */
  13
  14 /*
  15 FUNCTION
  16        <<ldexp>>, <<ldexpf>>---load exponent
  17
  18 INDEX
  19         ldexp
  20 INDEX
  21         ldexpf
  22
  23 ANSI_SYNOPSIS
  24        #include <math.h>
  25        double ldexp(double <[val]>, int <[exp]>);
  26        float ldexpf(float <[val]>, int <[exp]>);
  27
  28 TRAD_SYNOPSIS
  29        #include <math.h>
  30
  31        double ldexp(<[val]>, <[exp]>)
  32               double <[val]>;
  33               int <[exp]>;
  34
  35        float ldexpf(<[val]>, <[exp]>)
  36               float <[val]>;
  37               int <[exp]>;
  38
  39
  40 DESCRIPTION
  41 <<ldexp>> calculates the value
  42 @ifnottex
  43 <[val]> times 2 to the power <[exp]>.
  44 @end ifnottex
  45 @tex
  46 $val\times 2^{exp}$.
  47 @end tex
  48 <<ldexpf>> is identical, save that it takes and returns <<float>>
  49 rather than <<double>> values.
  50
  51 RETURNS
  52 <<ldexp>> returns the calculated value.
  53
  54 Underflow and overflow both set <<errno>> to <<ERANGE>>.
  55 On underflow, <<ldexp>> and <<ldexpf>> return 0.0.
  56 On overflow, <<ldexp>> returns plus or minus <<HUGE_VAL>>.
  57
  58 PORTABILITY
  59 <<ldexp>> is ANSI, <<ldexpf>> is an extension.
  60
  61 */
  62
  63 #include "fdlibm.h"
  64 #include <errno.h>
  65
  66 #ifndef _DOUBLE_IS_32BITS
  67
  68 #ifdef __STDC__
  69         double ldexp(double value, int exp)
  70 #else
  71         double ldexp(value, exp)
  72         double value; int exp;
  73 #endif
  74 {
  75         if(!finite(value)||value==0.0) return value;
  76         value = scalbn(value,exp);
  77         if(!finite(value)||value==0.0) errno = ERANGE;
  78         return value;
  79 }
  80
  81 #endif /* _DOUBLE_IS_32BITS */