minix/lib/libc/gnu/ieee_float/modf.c

61 lines
966 B
C

/*
libc/ieee_float/modf.c
Created: Oct 14, 1993 by Philip Homburg <philip@cs.vu.nl>
Implementation of modf that directly manipulates the exponent bits in an
ieee float
*/
#include <sys/types.h>
#include <math.h>
#include "ieee_float.h"
double modf(value, iptr)
double value;
double *iptr;
{
struct f64 *f64p;
double tmp;
int exp;
int mask_bits;
u32_t mant;
f64p= (struct f64 *)&value;
exp= F64_GET_EXP(f64p);
exp -= F64_EXP_BIAS;
if (exp < 0)
{
*iptr= 0;
return value;
}
mask_bits= 52-exp;
if (mask_bits <= 0)
{
*iptr= value;
return 0;
}
tmp= value;
if (mask_bits >= 32)
{
F64_SET_MANT_LOW(f64p, 0);
mask_bits -= 32;
mant= F64_GET_MANT_HIGH(f64p);
mant &= ~((1 << mask_bits)-1);
F64_SET_MANT_HIGH(f64p, mant);
}
else
{
mant= F64_GET_MANT_LOW(f64p);
mant &= ~((1 << mask_bits)-1);
F64_SET_MANT_LOW(f64p, mant);
}
*iptr= value;
return tmp-value;
}
/*
* $PchId: modf.c,v 1.3 1996/02/22 21:01:39 philip Exp $
*/