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/* @(#)z_ldexp.c 1.0 98/08/13 */
 
/*
FUNCTION
       <<ldexp>>, <<ldexpf>>---load exponent
 
INDEX
        ldexp
INDEX
        ldexpf
 
ANSI_SYNOPSIS
       #include <math.h>
       double ldexp(double <[val]>, int <[exp]>);
       float ldexpf(float <[val]>, int <[exp]>);
 
TRAD_SYNOPSIS
       #include <math.h>
 
       double ldexp(<[val]>, <[exp]>)
              double <[val]>;
              int <[exp]>;
 
       float ldexpf(<[val]>, <[exp]>)
              float <[val]>;
              int <[exp]>;
 
DESCRIPTION
<<ldexp>> calculates the value
@ifinfo
<[val]> times 2 to the power <[exp]>.
@end ifinfo
@tex
$val\times 2^{exp}$.
@end tex
<<ldexpf>> is identical, save that it takes and returns <<float>>
rather than <<double>> values.
 
RETURNS
<<ldexp>> returns the calculated value.
 
Underflow and overflow both set <<errno>> to <<ERANGE>>.
On underflow, <<ldexp>> and <<ldexpf>> return 0.0.
On overflow, <<ldexp>> returns plus or minus <<HUGE_VAL>>.
 
PORTABILITY
<<ldexp>> is ANSI, <<ldexpf>> is an extension.
 
*/
 
/******************************************************************
 * ldexp
 *
 * Input:
 *   d - a floating point value
 *   e - an exponent value
 *
 * Output:
 *   A floating point value f such that f = d * 2 ^ e.
 *
 * Description:
 *   This function creates a floating point number f such that
 *   f = d * 2 ^ e.
 *
 *****************************************************************/
 
#include <float.h>
#include "fdlibm.h"
#include "zmath.h"
 
#ifndef _DOUBLE_IS_32BITS
 
double
_DEFUN (ldexp, (double, int),
        double d _AND
        int e)
{
  int exp;
  __uint32_t hd;
 
  GET_HIGH_WORD (hd, d);
 
  /* Check for special values and then scale d by e. */
  switch (numtest (d))
    {
      case NAN:
        errno = EDOM;
        break;
 
      case INF:
        errno = ERANGE;
        break;
 
      case 0:
        break;
 
      default:
        exp = (hd & 0x7ff00000) >> 20;
        exp += e;
 
        if (exp > (DBL_MAX_EXP + 1023))
         {
           errno = ERANGE;
           d = z_infinity.d;
         }
        else if (exp < DBL_MIN_EXP)
         {
           errno = ERANGE;
           d = -z_infinity.d;
         }
        else
         {
           hd &= 0x800fffff;
           hd |= exp << 20;
           SET_HIGH_WORD (d, hd);
         }
    }
 
    return (d);
}
 
#endif /* _DOUBLE_IS_32BITS */

Line No.	Rev	Author	Line
1	56	joel
2			`/* @(#)z_ldexp.c 1.0 98/08/13 */`
3
4			`/*`
5			`FUNCTION`
6			`<<ldexp>>, <<ldexpf>>---load exponent`
7
8			`INDEX`
9			`ldexp`
10			`INDEX`
11			`ldexpf`
12
13			`ANSI_SYNOPSIS`
14			`#include <math.h>`
15			`double ldexp(double <[val]>, int <[exp]>);`
16			`float ldexpf(float <[val]>, int <[exp]>);`
17
18			`TRAD_SYNOPSIS`
19			`#include <math.h>`
20
21			`double ldexp(<[val]>, <[exp]>)`
22			`double <[val]>;`
23			`int <[exp]>;`
24
25			`float ldexpf(<[val]>, <[exp]>)`
26			`float <[val]>;`
27			`int <[exp]>;`
28
29			`DESCRIPTION`
30			`<<ldexp>> calculates the value`
31			`@ifinfo`
32			`<[val]> times 2 to the power <[exp]>.`
33			`@end ifinfo`
34			`@tex`
35			`$val\times 2^{exp}$.`
36			`@end tex`
37			`<<ldexpf>> is identical, save that it takes and returns <<float>>`
38			`rather than <<double>> values.`
39
40			`RETURNS`
41			`<<ldexp>> returns the calculated value.`
42
43			`Underflow and overflow both set <<errno>> to <<ERANGE>>.`
44			`On underflow, <<ldexp>> and <<ldexpf>> return 0.0.`
45			`On overflow, <<ldexp>> returns plus or minus <<HUGE_VAL>>.`
46
47			`PORTABILITY`
48			`<<ldexp>> is ANSI, <<ldexpf>> is an extension.`
49
50			`*/`
51
52			`/******************************************************************`
53			`* ldexp`
54			`*`
55			`* Input:`
56			`* d - a floating point value`
57			`* e - an exponent value`
58			`*`
59			`* Output:`
60			`* A floating point value f such that f = d * 2 ^ e.`
61			`*`
62			`* Description:`
63			`* This function creates a floating point number f such that`
64			`* f = d * 2 ^ e.`
65			`*`
66			`*****************************************************************/`
67
68			`#include <float.h>`
69			`#include "fdlibm.h"`
70			`#include "zmath.h"`
71
72			`#ifndef _DOUBLE_IS_32BITS`
73
74			`double`
75			`_DEFUN (ldexp, (double, int),`
76			`double d _AND`
77			`int e)`
78			`{`
79			`int exp;`
80			`__uint32_t hd;`
81
82			`GET_HIGH_WORD (hd, d);`
83
84			`/* Check for special values and then scale d by e. */`
85			`switch (numtest (d))`
86			`{`
87			`case NAN:`
88			`errno = EDOM;`
89			`break;`
90
91			`case INF:`
92			`errno = ERANGE;`
93			`break;`
94
95			`case 0:`
96			`break;`
97
98			`default:`
99			`exp = (hd & 0x7ff00000) >> 20;`
100			`exp += e;`
101
102			`if (exp > (DBL_MAX_EXP + 1023))`
103			`{`
104			`errno = ERANGE;`
105			`d = z_infinity.d;`
106			`}`
107			`else if (exp < DBL_MIN_EXP)`
108			`{`
109			`errno = ERANGE;`
110			`d = -z_infinity.d;`
111			`}`
112			`else`
113			`{`
114			`hd &= 0x800fffff;`
115			`hd \|= exp << 20;`
116			`SET_HIGH_WORD (d, hd);`
117			`}`
118			`}`
119
120			`return (d);`
121			`}`
122
123			`#endif /* _DOUBLE_IS_32BITS */`

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