[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.,
 *  59 Temple Place - Suite 330, Boston MA 02111-1307, 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 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
				&& get_rounding(sn, xm) >> (DP_FBITS + 1 + 3))
		{
			/* Not tiny after rounding */
			ieee754_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)) {
		ieee754_setcx(IEEE754_INEXACT);
		if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
			ieee754_setcx(IEEE754_UNDERFLOW);
		}

		/* inexact must round of 3 bits
		 */
		xm = 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 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
cae55066	26	#include <linux/compiler.h>
1da177e4 LT	27
	28	#include "ieee754dp.h"
	29
2209bcb1	30	int ieee754dp_class(union ieee754dp x)
1da177e4 LT	31	{
	32	COMPXDP;
	33	EXPLODEXDP;
	34	return xc;
	35	}
	36
2209bcb1	37	int ieee754dp_isnan(union ieee754dp x)
1da177e4 LT	38	{
	39	return ieee754dp_class(x) >= IEEE754_CLASS_SNAN;
	40	}
	41
f71baa11	42	static inline int ieee754dp_issnan(union ieee754dp x)
1da177e4 LT	43	{
1da177e4 LT	44	assert(ieee754dp_isnan(x));
ad8fb553	45	return ((DPMANT(x) & DP_MBIT(DP_FBITS-1)) == DP_MBIT(DP_FBITS-1));
1da177e4 LT	46	}
	47
	48
90efba36	49	union ieee754dp __cold ieee754dp_nanxcpt(union ieee754dp r)
1da177e4	50	{
1da177e4 LT	51	assert(ieee754dp_isnan(r));
	52
	53	if (!ieee754dp_issnan(r)) /* QNAN does not cause invalid op !! */
	54	return r;
	55
9e8bad1f	56	if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION)) {
1da177e4	57	/* not enabled convert to a quiet NaN */
ad8fb553	58	DPMANT(r) &= (~DP_MBIT(DP_FBITS-1));
1da177e4 LT	59	if (ieee754dp_isnan(r))
	60	return r;
	61	else
	62	return ieee754dp_indef();
	63	}
	64
90efba36	65	return r;
1da177e4 LT	66	}
1da177e4 LT	67
1da177e4 LT	68	static u64 get_rounding(int sn, u64 xm)
	69	{
	70	/* inexact must round of 3 bits
	71	*/
	72	if (xm & (DP_MBIT(3) - 1)) {
	73	switch (ieee754_csr.rm) {
	74	case IEEE754_RZ:
	75	break;
	76	case IEEE754_RN:
	77	xm += 0x3 + ((xm >> 3) & 1);
	78	/* xm += (xm&0x8)?0x4:0x3 */
	79	break;
	80	case IEEE754_RU: /* toward +Infinity */
	81	if (!sn) /* ?? */
	82	xm += 0x8;
	83	break;
	84	case IEEE754_RD: /* toward -Infinity */
70342287	85	if (sn) /* ?? */
1da177e4 LT	86	xm += 0x8;
	87	break;
	88	}
	89	}
	90	return xm;
	91	}
	92
	93
	94	/* generate a normal/denormal number with over,under handling
	95	* sn is sign
	96	* xe is an unbiased exponent
	97	* xm is 3bit extended precision value.
	98	*/
2209bcb1	99	union ieee754dp ieee754dp_format(int sn, int xe, u64 xm)
1da177e4 LT	100	{
	101	assert(xm); /* we don't gen exact zeros (probably should) */
	102
ad8fb553	103	assert((xm >> (DP_FBITS + 1 + 3)) == 0); /* no execess */
1da177e4 LT	104	assert(xm & (DP_HIDDEN_BIT << 3));
	105
	106	if (xe < DP_EMIN) {
	107	/* strip lower bits */
	108	int es = DP_EMIN - xe;
	109
	110	if (ieee754_csr.nod) {
9e8bad1f RB	111	ieee754_setcx(IEEE754_UNDERFLOW);
9e8bad1f RB	112	ieee754_setcx(IEEE754_INEXACT);
1da177e4 LT	113
	114	switch(ieee754_csr.rm) {
	115	case IEEE754_RN:
1da177e4 LT	116	case IEEE754_RZ:
	117	return ieee754dp_zero(sn);
	118	case IEEE754_RU: /* toward +Infinity */
47fa0c02	119	if (sn == 0)
1da177e4 LT	120	return ieee754dp_min(0);
	121	else
	122	return ieee754dp_zero(1);
	123	case IEEE754_RD: /* toward -Infinity */
47fa0c02	124	if (sn == 0)
1da177e4 LT	125	return ieee754dp_zero(0);
	126	else
	127	return ieee754dp_min(1);
	128	}
	129	}
	130
	131	if (xe == DP_EMIN - 1
ad8fb553	132	&& get_rounding(sn, xm) >> (DP_FBITS + 1 + 3))
1da177e4 LT	133	{
1da177e4 LT	134	/* Not tiny after rounding */
9e8bad1f	135	ieee754_setcx(IEEE754_INEXACT);
1da177e4 LT	136	xm = get_rounding(sn, xm);
	137	xm >>= 1;
	138	/* Clear grs bits */
	139	xm &= ~(DP_MBIT(3) - 1);
	140	xe++;
	141	}
	142	else {
	143	/* sticky right shift es bits
	144	*/
	145	xm = XDPSRS(xm, es);
	146	xe += es;
	147	assert((xm & (DP_HIDDEN_BIT << 3)) == 0);
	148	assert(xe == DP_EMIN);
	149	}
	150	}
	151	if (xm & (DP_MBIT(3) - 1)) {
9e8bad1f	152	ieee754_setcx(IEEE754_INEXACT);
1da177e4	153	if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
9e8bad1f	154	ieee754_setcx(IEEE754_UNDERFLOW);
1da177e4 LT	155	}
	156
	157	/* inexact must round of 3 bits
	158	*/
	159	xm = get_rounding(sn, xm);
	160	/* adjust exponent for rounding add overflowing
	161	*/
ad8fb553	162	if (xm >> (DP_FBITS + 3 + 1)) {
1da177e4 LT	163	/* add causes mantissa overflow */
	164	xm >>= 1;
	165	xe++;
	166	}
	167	}
	168	/* strip grs bits */
	169	xm >>= 3;
	170
ad8fb553	171	assert((xm >> (DP_FBITS + 1)) == 0); /* no execess */
1da177e4 LT	172	assert(xe >= DP_EMIN);
	173
	174	if (xe > DP_EMAX) {
9e8bad1f RB	175	ieee754_setcx(IEEE754_OVERFLOW);
9e8bad1f RB	176	ieee754_setcx(IEEE754_INEXACT);
1da177e4 LT	177	/* -O can be table indexed by (rm,sn) */
	178	switch (ieee754_csr.rm) {
	179	case IEEE754_RN:
	180	return ieee754dp_inf(sn);
	181	case IEEE754_RZ:
	182	return ieee754dp_max(sn);
	183	case IEEE754_RU: /* toward +Infinity */
	184	if (sn == 0)
	185	return ieee754dp_inf(0);
	186	else
	187	return ieee754dp_max(1);
	188	case IEEE754_RD: /* toward -Infinity */
	189	if (sn == 0)
	190	return ieee754dp_max(0);
	191	else
	192	return ieee754dp_inf(1);
	193	}
	194	}
	195	/* gen norm/denorm/zero */
	196
	197	if ((xm & DP_HIDDEN_BIT) == 0) {
	198	/* we underflow (tiny/zero) */
	199	assert(xe == DP_EMIN);
	200	if (ieee754_csr.mx & IEEE754_UNDERFLOW)
9e8bad1f	201	ieee754_setcx(IEEE754_UNDERFLOW);
1da177e4 LT	202	return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm);
1da177e4 LT	203	} else {
ad8fb553	204	assert((xm >> (DP_FBITS + 1)) == 0); /* no execess */
1da177e4 LT	205	assert(xm & DP_HIDDEN_BIT);
	206
	207	return builddp(sn, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
	208	}
	209	}