[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 <stdarg.h>
#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;
}

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


union ieee754dp __cold ieee754dp_xcpt(union ieee754dp r, const char *op, ...)
{
	struct ieee754xctx ax;
	if (!ieee754_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;
}

union ieee754dp __cold ieee754dp_nanxcpt(union 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 (!ieee754_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;
}

union ieee754dp ieee754dp_bestnan(union ieee754dp x, union 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.
 */
union 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) {
			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_MBITS + 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_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) {
		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_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
1eaf198d	26	#include <stdarg.h>
cae55066	27	#include <linux/compiler.h>
1da177e4 LT	28
	29	#include "ieee754dp.h"
	30
2209bcb1	31	int ieee754dp_class(union ieee754dp x)
1da177e4 LT	32	{
	33	COMPXDP;
	34	EXPLODEXDP;
	35	return xc;
	36	}
	37
2209bcb1	38	int ieee754dp_isnan(union ieee754dp x)
1da177e4 LT	39	{
	40	return ieee754dp_class(x) >= IEEE754_CLASS_SNAN;
	41	}
	42
2209bcb1	43	int ieee754dp_issnan(union ieee754dp x)
1da177e4 LT	44	{
	45	assert(ieee754dp_isnan(x));
	46	return ((DPMANT(x) & DP_MBIT(DP_MBITS-1)) == DP_MBIT(DP_MBITS-1));
	47	}
	48
	49
2209bcb1	50	union ieee754dp __cold ieee754dp_xcpt(union ieee754dp r, const char *op, ...)
1da177e4 LT	51	{
1da177e4 LT	52	struct ieee754xctx ax;
9e8bad1f	53	if (!ieee754_tstx())
1da177e4 LT	54	return r;
	55
	56	ax.op = op;
	57	ax.rt = IEEE754_RT_DP;
	58	ax.rv.dp = r;
	59	va_start(ax.ap, op);
	60	ieee754_xcpt(&ax);
8142294d	61	va_end(ax.ap);
1da177e4 LT	62	return ax.rv.dp;
	63	}
	64
2209bcb1	65	union ieee754dp __cold ieee754dp_nanxcpt(union ieee754dp r, const char *op, ...)
1da177e4 LT	66	{
	67	struct ieee754xctx ax;
	68
	69	assert(ieee754dp_isnan(r));
	70
	71	if (!ieee754dp_issnan(r)) /* QNAN does not cause invalid op !! */
	72	return r;
	73
9e8bad1f	74	if (!ieee754_setandtestcx(IEEE754_INVALID_OPERATION)) {
1da177e4 LT	75	/* not enabled convert to a quiet NaN */
	76	DPMANT(r) &= (~DP_MBIT(DP_MBITS-1));
	77	if (ieee754dp_isnan(r))
	78	return r;
	79	else
	80	return ieee754dp_indef();
	81	}
	82
	83	ax.op = op;
	84	ax.rt = 0;
	85	ax.rv.dp = r;
	86	va_start(ax.ap, op);
	87	ieee754_xcpt(&ax);
8142294d	88	va_end(ax.ap);
1da177e4 LT	89	return ax.rv.dp;
	90	}
	91
2209bcb1	92	union ieee754dp ieee754dp_bestnan(union ieee754dp x, union ieee754dp y)
1da177e4 LT	93	{
	94	assert(ieee754dp_isnan(x));
	95	assert(ieee754dp_isnan(y));
	96
	97	if (DPMANT(x) > DPMANT(y))
	98	return x;
	99	else
	100	return y;
	101	}
	102
	103
	104	static u64 get_rounding(int sn, u64 xm)
	105	{
	106	/* inexact must round of 3 bits
	107	*/
	108	if (xm & (DP_MBIT(3) - 1)) {
	109	switch (ieee754_csr.rm) {
	110	case IEEE754_RZ:
	111	break;
	112	case IEEE754_RN:
	113	xm += 0x3 + ((xm >> 3) & 1);
	114	/* xm += (xm&0x8)?0x4:0x3 */
	115	break;
	116	case IEEE754_RU: /* toward +Infinity */
	117	if (!sn) /* ?? */
	118	xm += 0x8;
	119	break;
	120	case IEEE754_RD: /* toward -Infinity */
70342287	121	if (sn) /* ?? */
1da177e4 LT	122	xm += 0x8;
	123	break;
	124	}
	125	}
	126	return xm;
	127	}
	128
	129
	130	/* generate a normal/denormal number with over,under handling
	131	* sn is sign
	132	* xe is an unbiased exponent
	133	* xm is 3bit extended precision value.
	134	*/
2209bcb1	135	union ieee754dp ieee754dp_format(int sn, int xe, u64 xm)
1da177e4 LT	136	{
	137	assert(xm); /* we don't gen exact zeros (probably should) */
	138
	139	assert((xm >> (DP_MBITS + 1 + 3)) == 0); /* no execess */
	140	assert(xm & (DP_HIDDEN_BIT << 3));
	141
	142	if (xe < DP_EMIN) {
	143	/* strip lower bits */
	144	int es = DP_EMIN - xe;
	145
	146	if (ieee754_csr.nod) {
9e8bad1f RB	147	ieee754_setcx(IEEE754_UNDERFLOW);
9e8bad1f RB	148	ieee754_setcx(IEEE754_INEXACT);
1da177e4 LT	149
	150	switch(ieee754_csr.rm) {
	151	case IEEE754_RN:
1da177e4 LT	152	case IEEE754_RZ:
	153	return ieee754dp_zero(sn);
	154	case IEEE754_RU: /* toward +Infinity */
47fa0c02	155	if (sn == 0)
1da177e4 LT	156	return ieee754dp_min(0);
	157	else
	158	return ieee754dp_zero(1);
	159	case IEEE754_RD: /* toward -Infinity */
47fa0c02	160	if (sn == 0)
1da177e4 LT	161	return ieee754dp_zero(0);
	162	else
	163	return ieee754dp_min(1);
	164	}
	165	}
	166
	167	if (xe == DP_EMIN - 1
	168	&& get_rounding(sn, xm) >> (DP_MBITS + 1 + 3))
	169	{
	170	/* Not tiny after rounding */
9e8bad1f	171	ieee754_setcx(IEEE754_INEXACT);
1da177e4 LT	172	xm = get_rounding(sn, xm);
	173	xm >>= 1;
	174	/* Clear grs bits */
	175	xm &= ~(DP_MBIT(3) - 1);
	176	xe++;
	177	}
	178	else {
	179	/* sticky right shift es bits
	180	*/
	181	xm = XDPSRS(xm, es);
	182	xe += es;
	183	assert((xm & (DP_HIDDEN_BIT << 3)) == 0);
	184	assert(xe == DP_EMIN);
	185	}
	186	}
	187	if (xm & (DP_MBIT(3) - 1)) {
9e8bad1f	188	ieee754_setcx(IEEE754_INEXACT);
1da177e4	189	if ((xm & (DP_HIDDEN_BIT << 3)) == 0) {
9e8bad1f	190	ieee754_setcx(IEEE754_UNDERFLOW);
1da177e4 LT	191	}
	192
	193	/* inexact must round of 3 bits
	194	*/
	195	xm = get_rounding(sn, xm);
	196	/* adjust exponent for rounding add overflowing
	197	*/
	198	if (xm >> (DP_MBITS + 3 + 1)) {
	199	/* add causes mantissa overflow */
	200	xm >>= 1;
	201	xe++;
	202	}
	203	}
	204	/* strip grs bits */
	205	xm >>= 3;
	206
	207	assert((xm >> (DP_MBITS + 1)) == 0); /* no execess */
	208	assert(xe >= DP_EMIN);
	209
	210	if (xe > DP_EMAX) {
9e8bad1f RB	211	ieee754_setcx(IEEE754_OVERFLOW);
9e8bad1f RB	212	ieee754_setcx(IEEE754_INEXACT);
1da177e4 LT	213	/* -O can be table indexed by (rm,sn) */
	214	switch (ieee754_csr.rm) {
	215	case IEEE754_RN:
	216	return ieee754dp_inf(sn);
	217	case IEEE754_RZ:
	218	return ieee754dp_max(sn);
	219	case IEEE754_RU: /* toward +Infinity */
	220	if (sn == 0)
	221	return ieee754dp_inf(0);
	222	else
	223	return ieee754dp_max(1);
	224	case IEEE754_RD: /* toward -Infinity */
	225	if (sn == 0)
	226	return ieee754dp_max(0);
	227	else
	228	return ieee754dp_inf(1);
	229	}
	230	}
	231	/* gen norm/denorm/zero */
	232
	233	if ((xm & DP_HIDDEN_BIT) == 0) {
	234	/* we underflow (tiny/zero) */
	235	assert(xe == DP_EMIN);
	236	if (ieee754_csr.mx & IEEE754_UNDERFLOW)
9e8bad1f	237	ieee754_setcx(IEEE754_UNDERFLOW);
1da177e4 LT	238	return builddp(sn, DP_EMIN - 1 + DP_EBIAS, xm);
	239	} else {
	240	assert((xm >> (DP_MBITS + 1)) == 0); /* no execess */
	241	assert(xm & DP_HIDDEN_BIT);
	242
	243	return builddp(sn, xe + DP_EBIAS, xm & ~DP_HIDDEN_BIT);
	244	}
	245	}