_q_add.c

操作系统SunOS 4.1.3版本的源码

#ifndef lint
static	char sccsid[] = "@(#)_Q_add.c 1.1 92/07/30 SMI";
#endif

/*
 * Copyright (c) 1988 by Sun Microsystems, Inc.
 */

#include "_Qquad.h"
#include "_Qglobals.h"

static double zero = 0.0, tiny = 1.0e-300, huge = 1.0e300;
static dummy();
extern _Q_get_rp_rd(), _Q_set_exception();

QUAD 
_Q_add(x,y)
	QUAD x,y;
{
	unpacked	px,py,pz;
	QUAD		z;
	_fp_current_exceptions = 0;
	_Q_get_rp_rd();		/* get fp_precision, fp_direction */
	_fp_unpack(&px,&x,fp_op_extended);
	_fp_unpack(&py,&y,fp_op_extended);
	_fp_add(&px,&py,&pz);
	_fp_pack(&pz,&z,fp_op_extended);
	_Q_set_exception(_fp_current_exceptions);
	return z;
}

/* don't use ieee_flags(), use machine dependent routine 
_Q_get_rp_rd()
{
	char		*out;
	fp_precision = ieee_flags("get","precision","",&out);
	fp_direction = ieee_flags("get","direction","",&out);
	return 0;
}
*/

_Q_set_exception(ex)
	unsigned ex;
{
    /* simulate exceptions using double arithmetic */
	double t;
	if((ex&(1<<fp_invalid))!=0)	t = (zero/zero);
	if((ex&(1<<fp_overflow))!=0)	t = (huge*huge);
	if((ex&(1<<fp_underflow))!=0)	t = (tiny*tiny);
	if((ex&(1<<fp_division))!=0)	t = (tiny/zero);
	if((ex&(1<<fp_inexact))!=0)	t = (huge+tiny);
	dummy(t);  /* prevent optimizer eliminating previous expression */
	return 0;
}
	
static 
dummy(x)
	double x;
{
	return 0;
}