72 lines
1 KiB
C
72 lines
1 KiB
C
/*
|
|
* (c) copyright 1987 by the Vrije Universiteit, Amsterdam, The Netherlands.
|
|
* See the copyright notice in the ACK home directory, in the file "Copyright".
|
|
*/
|
|
/* $Id$ */
|
|
|
|
#include <math.h>
|
|
#include <float.h>
|
|
#include <errno.h>
|
|
#include <ack/config.h>
|
|
|
|
#if ACKCONF_WANT_FLOAT
|
|
|
|
double
|
|
ldexp(double fl, int exp)
|
|
{
|
|
int sign = 1;
|
|
int currexp;
|
|
|
|
if (__IsNan(fl))
|
|
{
|
|
errno = EDOM;
|
|
return fl;
|
|
}
|
|
if (fl == 0.0)
|
|
return 0.0;
|
|
if (fl < 0)
|
|
{
|
|
fl = -fl;
|
|
sign = -1;
|
|
}
|
|
if (fl > DBL_MAX)
|
|
{ /* for infinity */
|
|
errno = ERANGE;
|
|
return sign * fl;
|
|
}
|
|
fl = frexp(fl, &currexp);
|
|
exp += currexp;
|
|
if (exp > 0)
|
|
{
|
|
if (exp > DBL_MAX_EXP)
|
|
{
|
|
errno = ERANGE;
|
|
return sign * HUGE_VAL;
|
|
}
|
|
while (exp > 30)
|
|
{
|
|
fl *= (double)(1L << 30);
|
|
exp -= 30;
|
|
}
|
|
fl *= (double)(1L << exp);
|
|
}
|
|
else
|
|
{
|
|
/* number need not be normalized */
|
|
if (exp < DBL_MIN_EXP - DBL_MANT_DIG)
|
|
{
|
|
return 0.0;
|
|
}
|
|
while (exp < -30)
|
|
{
|
|
fl /= (double)(1L << 30);
|
|
exp += 30;
|
|
}
|
|
fl /= (double)(1L << -exp);
|
|
}
|
|
return sign * fl;
|
|
}
|
|
|
|
#endif
|
|
|