[deliverable/linux.git] / arch / mips / math-emu / ieee754dp.c

/* IEEE754 floating point arithmetic
 * double precision: common utilities
 */
/*
 * 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 "ieee754dp.h"

int ieee754dp_class(ieee754dp x)
{
	COMPXDP;
	EXPLODEXDP;
	return xc;
}

int ieee754dp_isnan(ieee754dp x)
{
	return ieee754dp_class(x) >= IEEE754_CLASS_SNAN;
}

int ieee754dp_issnan(ieee754dp x)
{
	assert(ieee754dp_isnan(x));
	return ((DPMANT(x) & DP_MBIT(DP_MBITS-1)) == DP_MBIT(DP_MBITS-1));
}


ieee754dp ieee754dp_xcpt(ieee754dp r, const char *op, ...)
{
	struct ieee754xctx ax;
	if (!TSTX())
		return r;

	ax.op = op;
	ax.rt = IEEE754_RT_DP;
	ax.rv.dp = r;
	va_start(ax.ap, op);
	ieee754_xcpt(&ax);
	va_end(ax.ap);
	return ax.rv.dp;
}

ieee754dp ieee754dp_nanxcpt(ieee754dp r, const char *op, ...)
{
	struct ieee754xctx ax;

	assert(ieee754dp_isnan(r));

	if (!ieee754dp_issnan(r))	/* QNAN does not cause invalid op !! */
		return r;

	if (!SETANDTESTCX(IEEE754_INVALID_OPERATION)) {
		/* not enabled convert to a quiet NaN */
		DPMANT(r) &= (~DP_MBIT(DP_MBITS-1));
		if (ieee754dp_isnan(r))
			return r;
		else
			return ieee754dp_indef();
	}

	ax.op = op;
	ax.rt = 0;
	ax.rv.dp = r;
	va_start(ax.ap, op);
	ieee754_xcpt(&ax);
	va_end(ax.ap);
	return ax.rv.dp;
}

ieee754dp ieee754dp_bestnan(ieee754dp x, ieee754dp y)
{
	assert(ieee754dp_isnan(x));
	assert(ieee754dp_isnan(y));

	if (DPMANT(x) > DPMANT(y))
		return x;
	else
		return y;
}


static u64 get_rounding(int sn, u64 xm)
{
	/* inexact must round of 3 bits
	 */
	if (xm & (DP_MBIT(3) - 1)) {
		switch (ieee754_csr.rm) {
		case IEEE754_RZ:
			break;
		case IEEE754_RN:
			xm += 0x3 + ((xm >> 3) & 1);
			/* xm += (xm&0x8)?0x4:0x3 */
			break;
		case IEEE754_RU:	/* toward +Infinity */
			if (!sn)	/* ?? */
				xm += 0x8;
			break;
		case IEEE754_RD:	/* toward -Infinity */
			if (sn)	/* ?? */
				xm += 0x8;
			break;
		}
	}
	return xm;
}


/* generate a normal/denormal number with over,under handling
 * sn is sign
 * xe is an unbiased exponent
 * xm is 3bit extended precision value.
 */
ieee754dp ieee754dp_format(int sn, int xe, u64 xm)
{
	assert(xm);		/* we don't gen exact zeros (probably should) */

	assert((xm >> (DP_MBITS + 1 + 3)) == 0);	/* no execess */
	assert(xm & (DP_HIDDEN_BIT << 3));

	if (xe < DP_EMIN) {
		/* strip lower bits */
		int es = DP_EMIN - xe;

		if (ieee754_csr.nod) {
			SETCX(IEEE754_UNDERFLOW);
			SETCX(IEEE754_INEXACT);

			switch(ieee754_csr.rm) {
			case IEEE754_RN:
			case IEEE754_RZ:
				return ieee754dp_zero(sn);
			case IEEE754_RU:    /* toward +Infinity */
				if(sn == 0)
					return ieee754dp_min(0);
				else
					return ieee754dp_zero(1);
			case IEEE754_RD:    /* toward -Infinity */
				if(sn == 0)
					return ieee754dp_zero(0);
				else
					return ieee754dp_min(1);
			}
		}

		if (xe == DP_EMIN - 1
				&& get_rounding(sn, xm) >> (DP_MBITS + 1 + 3))
		{
			/* Not tiny after rounding */
			SETCX(IEEE754_INEXACT);
			xm = get_rounding(sn, xm);
			xm >>= 1;
			/* Clear grs bits */
			xm &= ~(DP_MBIT(3) - 1);
			xe++;
		}
		else {
			/* sticky right shift es bits
			 */
			xm = XDPSRS(xm, es);
			xe += es;
			assert((xm & (DP_HIDDEN_BIT << 3)) == 0);
			assert(xe == DP_EMIN);
		}
	}
	if (xm & (DP_MBIT(3) - 1)) {
		SETCX(IEEE754_INEXACT);
		if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
			SETCX(IEEE754_UNDERFLOW);
		}

		/* inexact must round of 3 bits
		 */
		xm = get_rounding(sn, xm);
		/* adjust exponent for rounding add overflowing
		 */
		if (xm >> (DP_MBITS + 3 + 1)) {
			/* add causes mantissa overflow */
			xm >>= 1;
			xe++;
		}
	}
	/* strip grs bits */
	xm >>= 3;

	assert((xm >> (DP_MBITS + 1)) == 0);	/* no execess */
	assert(xe >= DP_EMIN);

	if (xe > DP_EMAX) {
		SETCX(IEEE754_OVERFLOW);
		SETCX(IEEE754_INEXACT);
		/* -O can be table indexed by (rm,sn) */
		switch (ieee754_csr.rm) {
		case IEEE754_RN:
			return ieee754dp_inf(sn);
		case IEEE754_RZ:
			return ieee754dp_max(sn);
		case IEEE754_RU:	/* toward +Infinity */
			if (sn == 0)
				return ieee754dp_inf(0);
			else
				return ieee754dp_max(1);
		case IEEE754_RD:	/* toward -Infinity */
			if (sn == 0)
				return ieee754dp_max(0);
			else
				return ieee754dp_inf(1);
		}
	}
	/* gen norm/denorm/zero */

	if ((xm & DP_HIDDEN_BIT) == 0) {
		/* we underflow (tiny/zero) */
		assert(xe == DP_EMIN);
		if (ieee754_csr.mx & IEEE754_UNDERFLOW)
			SETCX(IEEE754_UNDERFLOW);
		return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm);
	} else {
		assert((xm >> (DP_MBITS + 1)) == 0);	/* no execess */
		assert(xm & DP_HIDDEN_BIT);

		return builddp(sn, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
	}
}
Commit	Line	Data
1da177e4 LT	1	/* IEEE754 floating point arithmetic
	2	* double precision: common utilities
	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 "ieee754dp.h"
	28
	29	int ieee754dp_class(ieee754dp x)
	30	{
	31	COMPXDP;
	32	EXPLODEXDP;
	33	return xc;
	34	}
	35
	36	int ieee754dp_isnan(ieee754dp x)
	37	{
	38	return ieee754dp_class(x) >= IEEE754_CLASS_SNAN;
	39	}
	40
	41	int ieee754dp_issnan(ieee754dp x)
	42	{
	43	assert(ieee754dp_isnan(x));
	44	return ((DPMANT(x) & DP_MBIT(DP_MBITS-1)) == DP_MBIT(DP_MBITS-1));
	45	}
	46
	47
	48	ieee754dp ieee754dp_xcpt(ieee754dp r, const char *op, ...)
	49	{
	50	struct ieee754xctx ax;
	51	if (!TSTX())
	52	return r;
	53
	54	ax.op = op;
	55	ax.rt = IEEE754_RT_DP;
	56	ax.rv.dp = r;
	57	va_start(ax.ap, op);
	58	ieee754_xcpt(&ax);
8142294d	59	va_end(ax.ap);
1da177e4 LT	60	return ax.rv.dp;
	61	}
	62
	63	ieee754dp ieee754dp_nanxcpt(ieee754dp r, const char *op, ...)
	64	{
	65	struct ieee754xctx ax;
	66
	67	assert(ieee754dp_isnan(r));
	68
	69	if (!ieee754dp_issnan(r)) /* QNAN does not cause invalid op !! */
	70	return r;
	71
	72	if (!SETANDTESTCX(IEEE754_INVALID_OPERATION)) {
	73	/* not enabled convert to a quiet NaN */
	74	DPMANT(r) &= (~DP_MBIT(DP_MBITS-1));
	75	if (ieee754dp_isnan(r))
	76	return r;
	77	else
	78	return ieee754dp_indef();
	79	}
	80
	81	ax.op = op;
	82	ax.rt = 0;
	83	ax.rv.dp = r;
	84	va_start(ax.ap, op);
	85	ieee754_xcpt(&ax);
8142294d	86	va_end(ax.ap);
1da177e4 LT	87	return ax.rv.dp;
	88	}
	89
	90	ieee754dp ieee754dp_bestnan(ieee754dp x, ieee754dp y)
	91	{
	92	assert(ieee754dp_isnan(x));
	93	assert(ieee754dp_isnan(y));
	94
	95	if (DPMANT(x) > DPMANT(y))
	96	return x;
	97	else
	98	return y;
	99	}
	100
	101
	102	static u64 get_rounding(int sn, u64 xm)
	103	{
	104	/* inexact must round of 3 bits
	105	*/
	106	if (xm & (DP_MBIT(3) - 1)) {
	107	switch (ieee754_csr.rm) {
	108	case IEEE754_RZ:
	109	break;
	110	case IEEE754_RN:
	111	xm += 0x3 + ((xm >> 3) & 1);
	112	/* xm += (xm&0x8)?0x4:0x3 */
	113	break;
	114	case IEEE754_RU: /* toward +Infinity */
	115	if (!sn) /* ?? */
	116	xm += 0x8;
	117	break;
	118	case IEEE754_RD: /* toward -Infinity */
	119	if (sn) /* ?? */
	120	xm += 0x8;
	121	break;
	122	}
	123	}
	124	return xm;
	125	}
	126
	127
	128	/* generate a normal/denormal number with over,under handling
	129	* sn is sign
	130	* xe is an unbiased exponent
	131	* xm is 3bit extended precision value.
	132	*/
	133	ieee754dp ieee754dp_format(int sn, int xe, u64 xm)
	134	{
	135	assert(xm); /* we don't gen exact zeros (probably should) */
	136
	137	assert((xm >> (DP_MBITS + 1 + 3)) == 0); /* no execess */
	138	assert(xm & (DP_HIDDEN_BIT << 3));
	139
	140	if (xe < DP_EMIN) {
	141	/* strip lower bits */
	142	int es = DP_EMIN - xe;
	143
	144	if (ieee754_csr.nod) {
	145	SETCX(IEEE754_UNDERFLOW);
	146	SETCX(IEEE754_INEXACT);
	147
	148	switch(ieee754_csr.rm) {
	149	case IEEE754_RN:
1da177e4 LT	150	case IEEE754_RZ:
	151	return ieee754dp_zero(sn);
	152	case IEEE754_RU: /* toward +Infinity */
	153	if(sn == 0)
	154	return ieee754dp_min(0);
	155	else
	156	return ieee754dp_zero(1);
	157	case IEEE754_RD: /* toward -Infinity */
	158	if(sn == 0)
	159	return ieee754dp_zero(0);
	160	else
	161	return ieee754dp_min(1);
	162	}
	163	}
	164
	165	if (xe == DP_EMIN - 1
	166	&& get_rounding(sn, xm) >> (DP_MBITS + 1 + 3))
	167	{
	168	/* Not tiny after rounding */
	169	SETCX(IEEE754_INEXACT);
	170	xm = get_rounding(sn, xm);
	171	xm >>= 1;
	172	/* Clear grs bits */
	173	xm &= ~(DP_MBIT(3) - 1);
	174	xe++;
	175	}
	176	else {
	177	/* sticky right shift es bits
	178	*/
	179	xm = XDPSRS(xm, es);
	180	xe += es;
	181	assert((xm & (DP_HIDDEN_BIT << 3)) == 0);
	182	assert(xe == DP_EMIN);
	183	}
	184	}
	185	if (xm & (DP_MBIT(3) - 1)) {
	186	SETCX(IEEE754_INEXACT);
	187	if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
	188	SETCX(IEEE754_UNDERFLOW);
	189	}
	190
	191	/* inexact must round of 3 bits
	192	*/
	193	xm = get_rounding(sn, xm);
	194	/* adjust exponent for rounding add overflowing
	195	*/
	196	if (xm >> (DP_MBITS + 3 + 1)) {
	197	/* add causes mantissa overflow */
	198	xm >>= 1;
	199	xe++;
	200	}
	201	}
	202	/* strip grs bits */
	203	xm >>= 3;
	204
	205	assert((xm >> (DP_MBITS + 1)) == 0); /* no execess */
	206	assert(xe >= DP_EMIN);
	207
	208	if (xe > DP_EMAX) {
	209	SETCX(IEEE754_OVERFLOW);
	210	SETCX(IEEE754_INEXACT);
	211	/* -O can be table indexed by (rm,sn) */
	212	switch (ieee754_csr.rm) {
	213	case IEEE754_RN:
214	return ieee754dp_inf(sn);
215	case IEEE754_RZ:
216	return ieee754dp_max(sn);
217	case IEEE754_RU: /* toward +Infinity */
218	if (sn == 0)
219	return ieee754dp_inf(0);
220	else
221	return ieee754dp_max(1);
222	case IEEE754_RD: /* toward -Infinity */
223	if (sn == 0)
224	return ieee754dp_max(0);
225	else
226	return ieee754dp_inf(1);
227	}
228	}
229	/* gen norm/denorm/zero */
230
231	if ((xm & DP_HIDDEN_BIT) == 0) {
232	/* we underflow (tiny/zero) */
233	assert(xe == DP_EMIN);
234	if (ieee754_csr.mx & IEEE754_UNDERFLOW)
235	SETCX(IEEE754_UNDERFLOW);
236	return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm);
237	} else {
238	assert((xm >> (DP_MBITS + 1)) == 0); /* no execess */
239	assert(xm & DP_HIDDEN_BIT);
240
241	return builddp(sn, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
242	}
243	}