/* _Dint function -- IEEE 754 version */
#include "xmath.h"

short _Dint(double *px, short xexp)
	{	/* test and drop (scaled) fraction bits */
	_Dval *ps = (_Dval *)(char *)px;
	unsigned short frac;
	short xchar = (ps->_Sh[_D0] & _DMASK) >> _DOFF;

	if (xchar == _DMAX)
		return ((ps->_Sh[_D0] & _DFRAC) == 0 && ps->_Sh[_D1] == 0
			&& ps->_Sh[_D2] == 0 && ps->_Sh[_D3] == 0
			? _INFCODE : _NANCODE);
	else if ((ps->_Sh[_D0] & ~_DSIGN) == 0 && ps->_Sh[_D1] == 0
		&& ps->_Sh[_D2] == 0 && ps->_Sh[_D3] == 0)
		return (0);
	xchar = (_DBIAS + 48 + _DOFF + 1) - xchar - xexp;
	if (xchar <= 0)
		return (0);	/* no frac bits to drop */
	else if ((48 + _DOFF + 1) <= xchar)
		{	/* all frac bits */
		ps->_Sh[_D0] &= _DSIGN;
		ps->_Sh[_D1] = 0;
		ps->_Sh[_D2] = 0;
		ps->_Sh[_D3] = 0;
		return (_FINITE);	/* report on frac, not result */
		}
	else
		{	/* strip out frac bits */
		static const unsigned short mask[] = {
			0x0000, 0x0001, 0x0003, 0x0007,
			0x000f, 0x001f, 0x003f, 0x007f,
			0x00ff, 0x01ff, 0x03ff, 0x07ff,
			0x0fff, 0x1fff, 0x3fff, 0x7fff};
		static const size_t sub[] = {_D3, _D2, _D1, _D0};

		frac = mask[xchar & 0xf];
		xchar >>= 4;
		frac &= ps->_Sh[sub[xchar]];
		ps->_Sh[sub[xchar]] ^= frac;
		switch (xchar)
			{	/* cascade through! */
		case 3:
			frac |= ps->_Sh[_D1], ps->_Sh[_D1] = 0;
		case 2:
			frac |= ps->_Sh[_D2], ps->_Sh[_D2] = 0;
		case 1:
			frac |= ps->_Sh[_D3], ps->_Sh[_D3] = 0;
			}
		return (frac != 0 ? _FINITE : 0);
		}
	}

/*
 * Copyright (c) by P.J. Plauger. All rights reserved.
 * Consult your license regarding permissions and restrictions.
V6.50:0009 */