Charles.Forsyth20060303a828770d19 years agoHistory
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#include <lib9.h> #define	MASK	0x7ffL#define	SHIFT	20#define	BIAS	1022L typedef	union{	double	d;	struct	/* this is BIGENDIAN */	{		long	ms;		long	ls;	};} Cheat; doublefrexp(double d, int *ep){	Cheat x; 	if(d == 0) {		*ep = 0;		return 0;	}	x.d = d;	*ep = ((x.ms >> SHIFT) & MASK) - BIAS;	x.ms &= ~(MASK << SHIFT);	x.ms |= BIAS << SHIFT;	return x.d;} doubleldexp(double d, int e){	Cheat x; 	if(d == 0)		return 0;	x.d = d;	e += (x.ms >> SHIFT) & MASK;	if(e <= 0)		return 0;	/* underflow */	if(e >= MASK){		/* overflow */		if(d < 0)			return Inf(-1);		return Inf(1);	}	x.ms &= ~(MASK << SHIFT);	x.ms |= (long)e << SHIFT;	return x.d;} doublemodf(double d, double *ip){	Cheat x;	int e; 	if(d < 1) {		if(d < 0) {			x.d = modf(-d, ip);			*ip = -*ip;			return -x.d;		}		*ip = 0;		return d;	}	x.d = d;	e = ((x.ms >> SHIFT) & MASK) - BIAS;	if(e <= SHIFT+1) {		x.ms &= ~(0x1fffffL >> e);		x.ls = 0;	} else	if(e <= SHIFT+33)		x.ls &= ~(0x7fffffffL >> (e-SHIFT-2));	*ip = x.d;	return d - x.d;}