minix/lib/gnu/ieee_float/frexp.c

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/*
libc/ieee_float/frexp.c
Created: Oct 14, 1993 by Philip Homburg <philip@cs.vu.nl>
Implementation of frexp that directly manipulates the exponent bits in an
ieee float
*/
#include <sys/types.h>
#include <math.h>
#include "ieee_float.h"
double frexp(value, eptr)
double value;
int *eptr;
{
struct f64 *f64p;
int exp, exp_bias;
double factor;
f64p= (struct f64 *)&value;
exp_bias= 0;
exp= F64_GET_EXP(f64p);
if (exp == F64_EXP_MAX)
{ /* Either infinity or Nan */
*eptr= 0;
return value;
}
if (exp == 0)
{
/* Either 0 or denormal */
if (F64_GET_MANT_LOW(f64p) == 0 &&
F64_GET_MANT_HIGH(f64p) == 0)
{
*eptr= 0;
return value;
}
/* Multiply by 2^64 */
factor= 65536.0; /* 2^16 */
factor *= factor; /* 2^32 */
factor *= factor; /* 2^64 */
value *= factor;
exp_bias= 64;
exp= F64_GET_EXP(f64p);
}
exp= exp - F64_EXP_BIAS - exp_bias + 1;
*eptr= exp;
F64_SET_EXP(f64p, F64_EXP_BIAS-1);
return value;
}
/*
* $PchId: frexp.c,v 1.3 1996/02/22 21:01:39 philip Exp $
*/