[linux-2.6-block.git] / arch / mips / math-emu / sp_modf.c

/* IEEE754 floating point arithmetic
 * single precision
 */
/*
 * MIPS floating point support
 * Copyright (C) 1994-2000 Algorithmics Ltd.
 *
 * ########################################################################
 *
 *  This program is free software; you can distribute it and/or modify it
 *  under the terms of the GNU General Public License (Version 2) as
 *  published by the Free Software Foundation.
 *
 *  This program is distributed in the hope it will be useful, but WITHOUT
 *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 *  for more details.
 *
 *  You should have received a copy of the GNU General Public License along
 *  with this program; if not, write to the Free Software Foundation, Inc.,
 *  59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
 *
 * ########################################################################
 */


#include "ieee754sp.h"

/* modf function is always exact for a finite number
*/
ieee754sp ieee754sp_modf(ieee754sp x, ieee754sp *ip)
{
	COMPXSP;

	CLEARCX;

	EXPLODEXSP;

	switch (xc) {
	case IEEE754_CLASS_SNAN:
	case IEEE754_CLASS_QNAN:
	case IEEE754_CLASS_INF:
	case IEEE754_CLASS_ZERO:
		*ip = x;
		return x;
	case IEEE754_CLASS_DNORM:
		/* far to small */
		*ip = ieee754sp_zero(xs);
		return x;
	case IEEE754_CLASS_NORM:
		break;
	}
	if (xe < 0) {
		*ip = ieee754sp_zero(xs);
		return x;
	}
	if (xe >= SP_MBITS) {
		*ip = x;
		return ieee754sp_zero(xs);
	}
	/* generate ipart mantissa by clearing bottom bits
	 */
	*ip = buildsp(xs, xe + SP_EBIAS,
		      ((xm >> (SP_MBITS - xe)) << (SP_MBITS - xe)) &
		      ~SP_HIDDEN_BIT);

	/* generate fpart mantissa by clearing top bits
	 * and normalizing (must be able to normalize)
	 */
	xm = (xm << (32 - (SP_MBITS - xe))) >> (32 - (SP_MBITS - xe));
	if (xm == 0)
		return ieee754sp_zero(xs);

	while ((xm >> SP_MBITS) == 0) {
		xm <<= 1;
		xe--;
	}
	return buildsp(xs, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT);
}
Commit	Line	Data
1da177e4 LT	1	/* IEEE754 floating point arithmetic
	2	* single precision
	3	*/
	4	/*
	5	* MIPS floating point support
	6	* Copyright (C) 1994-2000 Algorithmics Ltd.
1da177e4 LT	7	*
	8	* ########################################################################
	9	*
	10	* This program is free software; you can distribute it and/or modify it
	11	* under the terms of the GNU General Public License (Version 2) as
	12	* published by the Free Software Foundation.
	13	*
	14	* This program is distributed in the hope it will be useful, but WITHOUT
	15	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	16	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	17	* for more details.
	18	*
	19	* You should have received a copy of the GNU General Public License along
	20	* with this program; if not, write to the Free Software Foundation, Inc.,
	21	* 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
	22	*
	23	* ########################################################################
	24	*/
	25
	26
	27	#include "ieee754sp.h"
	28
	29	/* modf function is always exact for a finite number
	30	*/
24da36cd	31	ieee754sp ieee754sp_modf(ieee754sp x, ieee754sp *ip)
1da177e4 LT	32	{
	33	COMPXSP;
	34
	35	CLEARCX;
	36
	37	EXPLODEXSP;
	38
	39	switch (xc) {
	40	case IEEE754_CLASS_SNAN:
	41	case IEEE754_CLASS_QNAN:
	42	case IEEE754_CLASS_INF:
	43	case IEEE754_CLASS_ZERO:
	44	*ip = x;
	45	return x;
	46	case IEEE754_CLASS_DNORM:
	47	/* far to small */
	48	*ip = ieee754sp_zero(xs);
	49	return x;
	50	case IEEE754_CLASS_NORM:
	51	break;
	52	}
	53	if (xe < 0) {
	54	*ip = ieee754sp_zero(xs);
	55	return x;
	56	}
	57	if (xe >= SP_MBITS) {
	58	*ip = x;
	59	return ieee754sp_zero(xs);
	60	}
	61	/* generate ipart mantissa by clearing bottom bits
	62	*/
	63	*ip = buildsp(xs, xe + SP_EBIAS,
	64	((xm >> (SP_MBITS - xe)) << (SP_MBITS - xe)) &
	65	~SP_HIDDEN_BIT);
	66
	67	/* generate fpart mantissa by clearing top bits
	68	* and normalizing (must be able to normalize)
	69	*/
	70	xm = (xm << (32 - (SP_MBITS - xe))) >> (32 - (SP_MBITS - xe));
	71	if (xm == 0)
	72	return ieee754sp_zero(xs);
	73
	74	while ((xm >> SP_MBITS) == 0) {
	75	xm <<= 1;
	76	xe--;
	77	}
	78	return buildsp(xs, xe + SP_EBIAS, xm & ~SP_HIDDEN_BIT);
	79	}