[mirror_ubuntu-hirsute-kernel.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.,
 *  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA.
 */

#include <linux/compiler.h>

#include "ieee754dp.h"

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

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

static inline int ieee754dp_issnan(union ieee754dp x)
{
	assert(ieee754dp_isnan(x));
	return ((DPMANT(x) & DP_MBIT(DP_FBITS-1)) == DP_MBIT(DP_FBITS-1));
}


union ieee754dp __cold ieee754dp_nanxcpt(union ieee754dp r)
{
	assert(ieee754dp_isnan(r));

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

	if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION)) {
		/* not enabled convert to a quiet NaN */
		DPMANT(r) &= (~DP_MBIT(DP_FBITS-1));
		if (ieee754dp_isnan(r))
			return r;
		else
			return ieee754dp_indef();
	}

	return r;
}

static u64 ieee754dp_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.
 */
union ieee754dp ieee754dp_format(int sn, int xe, u64 xm)
{
	assert(xm);		/* we don't gen exact zeros (probably should) */

	assert((xm >> (DP_FBITS + 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) {
			ieee754_setcx(IEEE754_UNDERFLOW);
			ieee754_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 &&
		    ieee754dp_get_rounding(sn, xm) >> (DP_FBITS + 1 + 3))
		{
			/* Not tiny after rounding */
			ieee754_setcx(IEEE754_INEXACT);
			xm = ieee754dp_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)) {
		ieee754_setcx(IEEE754_INEXACT);
		if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
			ieee754_setcx(IEEE754_UNDERFLOW);
		}

		/* inexact must round of 3 bits
		 */
		xm = ieee754dp_get_rounding(sn, xm);
		/* adjust exponent for rounding add overflowing
		 */
		if (xm >> (DP_FBITS + 3 + 1)) {
			/* add causes mantissa overflow */
			xm >>= 1;
			xe++;
		}
	}
	/* strip grs bits */
	xm >>= 3;

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

	if (xe > DP_EMAX) {
		ieee754_setcx(IEEE754_OVERFLOW);
		ieee754_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)
			ieee754_setcx(IEEE754_UNDERFLOW);
		return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm);
	} else {
		assert((xm >> (DP_FBITS + 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	7	*
1da177e4 LT	8	* This program is free software; you can distribute it and/or modify it
	9	* under the terms of the GNU General Public License (Version 2) as
	10	* published by the Free Software Foundation.
	11	*
	12	* This program is distributed in the hope it will be useful, but WITHOUT
	13	* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
	14	* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
	15	* for more details.
	16	*
	17	* You should have received a copy of the GNU General Public License along
	18	* with this program; if not, write to the Free Software Foundation, Inc.,
3f7cac41	19	* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1da177e4 LT	20	*/
1da177e4 LT	21
cae55066	22	#include <linux/compiler.h>
1da177e4 LT	23
	24	#include "ieee754dp.h"
	25
2209bcb1	26	int ieee754dp_class(union ieee754dp x)
1da177e4 LT	27	{
	28	COMPXDP;
	29	EXPLODEXDP;
	30	return xc;
	31	}
	32
2209bcb1	33	int ieee754dp_isnan(union ieee754dp x)
1da177e4 LT	34	{
	35	return ieee754dp_class(x) >= IEEE754_CLASS_SNAN;
	36	}
	37
f71baa11	38	static inline int ieee754dp_issnan(union ieee754dp x)
1da177e4 LT	39	{
1da177e4 LT	40	assert(ieee754dp_isnan(x));
ad8fb553	41	return ((DPMANT(x) & DP_MBIT(DP_FBITS-1)) == DP_MBIT(DP_FBITS-1));
1da177e4 LT	42	}
	43
	44
90efba36	45	union ieee754dp __cold ieee754dp_nanxcpt(union ieee754dp r)
1da177e4	46	{
1da177e4 LT	47	assert(ieee754dp_isnan(r));
	48
	49	if (!ieee754dp_issnan(r)) /* QNAN does not cause invalid op !! */
	50	return r;
	51
9e8bad1f	52	if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION)) {
1da177e4	53	/* not enabled convert to a quiet NaN */
ad8fb553	54	DPMANT(r) &= (~DP_MBIT(DP_FBITS-1));
1da177e4 LT	55	if (ieee754dp_isnan(r))
	56	return r;
	57	else
	58	return ieee754dp_indef();
	59	}
	60
90efba36	61	return r;
1da177e4 LT	62	}
1da177e4 LT	63
de2fc342	64	static u64 ieee754dp_get_rounding(int sn, u64 xm)
1da177e4 LT	65	{
	66	/* inexact must round of 3 bits
	67	*/
	68	if (xm & (DP_MBIT(3) - 1)) {
	69	switch (ieee754_csr.rm) {
	70	case IEEE754_RZ:
	71	break;
	72	case IEEE754_RN:
	73	xm += 0x3 + ((xm >> 3) & 1);
	74	/* xm += (xm&0x8)?0x4:0x3 */
	75	break;
	76	case IEEE754_RU: /* toward +Infinity */
	77	if (!sn) /* ?? */
	78	xm += 0x8;
	79	break;
	80	case IEEE754_RD: /* toward -Infinity */
70342287	81	if (sn) /* ?? */
1da177e4 LT	82	xm += 0x8;
	83	break;
	84	}
	85	}
	86	return xm;
	87	}
	88
	89
	90	/* generate a normal/denormal number with over,under handling
	91	* sn is sign
	92	* xe is an unbiased exponent
	93	* xm is 3bit extended precision value.
	94	*/
2209bcb1	95	union ieee754dp ieee754dp_format(int sn, int xe, u64 xm)
1da177e4 LT	96	{
	97	assert(xm); /* we don't gen exact zeros (probably should) */
	98
ad8fb553	99	assert((xm >> (DP_FBITS + 1 + 3)) == 0); /* no execess */
1da177e4 LT	100	assert(xm & (DP_HIDDEN_BIT << 3));
	101
	102	if (xe < DP_EMIN) {
	103	/* strip lower bits */
	104	int es = DP_EMIN - xe;
	105
	106	if (ieee754_csr.nod) {
9e8bad1f RB	107	ieee754_setcx(IEEE754_UNDERFLOW);
9e8bad1f RB	108	ieee754_setcx(IEEE754_INEXACT);
1da177e4 LT	109
	110	switch(ieee754_csr.rm) {
	111	case IEEE754_RN:
1da177e4 LT	112	case IEEE754_RZ:
	113	return ieee754dp_zero(sn);
	114	case IEEE754_RU: /* toward +Infinity */
47fa0c02	115	if (sn == 0)
1da177e4 LT	116	return ieee754dp_min(0);
	117	else
	118	return ieee754dp_zero(1);
	119	case IEEE754_RD: /* toward -Infinity */
47fa0c02	120	if (sn == 0)
1da177e4 LT	121	return ieee754dp_zero(0);
	122	else
	123	return ieee754dp_min(1);
	124	}
	125	}
	126
de2fc342 RB	127	if (xe == DP_EMIN - 1 &&
de2fc342 RB	128	ieee754dp_get_rounding(sn, xm) >> (DP_FBITS + 1 + 3))
1da177e4 LT	129	{
1da177e4 LT	130	/* Not tiny after rounding */
9e8bad1f	131	ieee754_setcx(IEEE754_INEXACT);
de2fc342	132	xm = ieee754dp_get_rounding(sn, xm);
1da177e4 LT	133	xm >>= 1;
	134	/* Clear grs bits */
	135	xm &= ~(DP_MBIT(3) - 1);
	136	xe++;
	137	}
	138	else {
	139	/* sticky right shift es bits
	140	*/
	141	xm = XDPSRS(xm, es);
	142	xe += es;
	143	assert((xm & (DP_HIDDEN_BIT << 3)) == 0);
	144	assert(xe == DP_EMIN);
	145	}
	146	}
	147	if (xm & (DP_MBIT(3) - 1)) {
9e8bad1f	148	ieee754_setcx(IEEE754_INEXACT);
1da177e4	149	if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
9e8bad1f	150	ieee754_setcx(IEEE754_UNDERFLOW);
1da177e4 LT	151	}
	152
	153	/* inexact must round of 3 bits
	154	*/
de2fc342	155	xm = ieee754dp_get_rounding(sn, xm);
1da177e4 LT	156	/* adjust exponent for rounding add overflowing
1da177e4 LT	157	*/
ad8fb553	158	if (xm >> (DP_FBITS + 3 + 1)) {
1da177e4 LT	159	/* add causes mantissa overflow */
	160	xm >>= 1;
	161	xe++;
	162	}
	163	}
	164	/* strip grs bits */
	165	xm >>= 3;
	166
ad8fb553	167	assert((xm >> (DP_FBITS + 1)) == 0); /* no execess */
1da177e4 LT	168	assert(xe >= DP_EMIN);
	169
	170	if (xe > DP_EMAX) {
9e8bad1f RB	171	ieee754_setcx(IEEE754_OVERFLOW);
9e8bad1f RB	172	ieee754_setcx(IEEE754_INEXACT);
1da177e4 LT	173	/* -O can be table indexed by (rm,sn) */
	174	switch (ieee754_csr.rm) {
	175	case IEEE754_RN:
	176	return ieee754dp_inf(sn);
	177	case IEEE754_RZ:
	178	return ieee754dp_max(sn);
	179	case IEEE754_RU: /* toward +Infinity */
	180	if (sn == 0)
	181	return ieee754dp_inf(0);
	182	else
	183	return ieee754dp_max(1);
	184	case IEEE754_RD: /* toward -Infinity */
	185	if (sn == 0)
	186	return ieee754dp_max(0);
	187	else
	188	return ieee754dp_inf(1);
	189	}
	190	}
	191	/* gen norm/denorm/zero */
	192
	193	if ((xm & DP_HIDDEN_BIT) == 0) {
	194	/* we underflow (tiny/zero) */
	195	assert(xe == DP_EMIN);
	196	if (ieee754_csr.mx & IEEE754_UNDERFLOW)
9e8bad1f	197	ieee754_setcx(IEEE754_UNDERFLOW);
1da177e4 LT	198	return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm);
1da177e4 LT	199	} else {
ad8fb553	200	assert((xm >> (DP_FBITS + 1)) == 0); /* no execess */
1da177e4 LT	201	assert(xm & DP_HIDDEN_BIT);
	202
	203	return builddp(sn, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
	204	}
	205	}