[thirdparty/linux.git] / arch / mips / math-emu / dp_div.c

// SPDX-License-Identifier: GPL-2.0-only
/* IEEE754 floating point arithmetic
 * double precision: common utilities
 */
/*
 * MIPS floating point support
 * Copyright (C) 1994-2000 Algorithmics Ltd.
 */

#include "ieee754dp.h"

union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y)
{
	u64 rm;
	int re;
	u64 bm;

	COMPXDP;
	COMPYDP;

	EXPLODEXDP;
	EXPLODEYDP;

	ieee754_clearcx();

	FLUSHXDP;
	FLUSHYDP;

	switch (CLPAIR(xc, yc)) {
	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
		return ieee754dp_nanxcpt(y);

	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
		return ieee754dp_nanxcpt(x);

	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
		return y;

	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
		return x;


	/*
	 * Infinity handling
	 */
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
		ieee754_setcx(IEEE754_INVALID_OPERATION);
		return ieee754dp_indef();

	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
		return ieee754dp_zero(xs ^ ys);

	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
		return ieee754dp_inf(xs ^ ys);

	/*
	 * Zero handling
	 */
	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
		ieee754_setcx(IEEE754_INVALID_OPERATION);
		return ieee754dp_indef();

	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
		ieee754_setcx(IEEE754_ZERO_DIVIDE);
		return ieee754dp_inf(xs ^ ys);

	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
		return ieee754dp_zero(xs == ys ? 0 : 1);

	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
		DPDNORMX;
		/* fall through */

	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
		DPDNORMY;
		break;

	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
		DPDNORMX;
		break;

	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
		break;
	}
	assert(xm & DP_HIDDEN_BIT);
	assert(ym & DP_HIDDEN_BIT);

	/* provide rounding space */
	xm <<= 3;
	ym <<= 3;

	/* now the dirty work */

	rm = 0;
	re = xe - ye;

	for (bm = DP_MBIT(DP_FBITS + 2); bm; bm >>= 1) {
		if (xm >= ym) {
			xm -= ym;
			rm |= bm;
			if (xm == 0)
				break;
		}
		xm <<= 1;
	}

	rm <<= 1;
	if (xm)
		rm |= 1;	/* have remainder, set sticky */

	assert(rm);

	/*
	 * Normalise rm to rounding precision ?
	 */
	while ((rm >> (DP_FBITS + 3)) == 0) {
		rm <<= 1;
		re--;
	}

	return ieee754dp_format(xs == ys ? 0 : 1, re, rm);
}
Commit	Line	Data
9d5a6349	1	// SPDX-License-Identifier: GPL-2.0-only
1da177e4 LT	2	/* IEEE754 floating point arithmetic
	3	* double precision: common utilities
	4	*/
	5	/*
	6	* MIPS floating point support
	7	* Copyright (C) 1994-2000 Algorithmics Ltd.
1da177e4 LT	8	*/
1da177e4 LT	9
1da177e4 LT	10	#include "ieee754dp.h"
1da177e4 LT	11
2209bcb1	12	union ieee754dp ieee754dp_div(union ieee754dp x, union ieee754dp y)
1da177e4	13	{
3f7cac41 RB	14	u64 rm;
	15	int re;
	16	u64 bm;
	17
1da177e4 LT	18	COMPXDP;
	19	COMPYDP;
	20
	21	EXPLODEXDP;
	22	EXPLODEYDP;
	23
9e8bad1f	24	ieee754_clearcx();
1da177e4 LT	25
	26	FLUSHXDP;
	27	FLUSHYDP;
	28
	29	switch (CLPAIR(xc, yc)) {
1da177e4	30	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):
1da177e4 LT	31	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):
	32	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):
	33	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):
	34	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):
d5afa7e9 MR	35	return ieee754dp_nanxcpt(y);
	36
	37	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):
	38	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):
1da177e4 LT	39	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):
	40	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):
	41	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):
	42	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):
d5afa7e9	43	return ieee754dp_nanxcpt(x);
1da177e4 LT	44
	45	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):
	46	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):
	47	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):
	48	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):
	49	return y;
	50
	51	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):
	52	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):
	53	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):
	54	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):
	55	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):
	56	return x;
	57
	58
3f7cac41 RB	59	/*
	60	* Infinity handling
	61	*/
1da177e4	62	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
9e8bad1f	63	ieee754_setcx(IEEE754_INVALID_OPERATION);
90efba36	64	return ieee754dp_indef();
1da177e4 LT	65
	66	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
	67	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
	68	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
	69	return ieee754dp_zero(xs ^ ys);
	70
	71	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
	72	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
	73	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
	74	return ieee754dp_inf(xs ^ ys);
	75
3f7cac41 RB	76	/*
	77	* Zero handling
	78	*/
1da177e4	79	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
9e8bad1f	80	ieee754_setcx(IEEE754_INVALID_OPERATION);
90efba36	81	return ieee754dp_indef();
1da177e4 LT	82
	83	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
	84	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
9e8bad1f	85	ieee754_setcx(IEEE754_ZERO_DIVIDE);
90efba36	86	return ieee754dp_inf(xs ^ ys);
1da177e4 LT	87
	88	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
	89	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
	90	return ieee754dp_zero(xs == ys ? 0 : 1);
	91
	92	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
	93	DPDNORMX;
2a14b21a	94	/* fall through */
1da177e4 LT	95
	96	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
	97	DPDNORMY;
	98	break;
	99
	100	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
	101	DPDNORMX;
	102	break;
	103
	104	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
	105	break;
	106	}
	107	assert(xm & DP_HIDDEN_BIT);
	108	assert(ym & DP_HIDDEN_BIT);
	109
	110	/* provide rounding space */
	111	xm <<= 3;
	112	ym <<= 3;
	113
3f7cac41	114	/* now the dirty work */
1da177e4	115
3f7cac41 RB	116	rm = 0;
3f7cac41 RB	117	re = xe - ye;
1da177e4	118
3f7cac41 RB	119	for (bm = DP_MBIT(DP_FBITS + 2); bm; bm >>= 1) {
	120	if (xm >= ym) {
	121	xm -= ym;
	122	rm \|= bm;
	123	if (xm == 0)
	124	break;
1da177e4	125	}
3f7cac41 RB	126	xm <<= 1;
	127	}
	128
	129	rm <<= 1;
	130	if (xm)
	131	rm \|= 1; /* have remainder, set sticky */
1da177e4	132
3f7cac41 RB	133	assert(rm);
	134
	135	/*
	136	* Normalise rm to rounding precision ?
	137	*/
	138	while ((rm >> (DP_FBITS + 3)) == 0) {
	139	rm <<= 1;
	140	re--;
1da177e4	141	}
3f7cac41 RB	142
3f7cac41 RB	143	return ieee754dp_format(xs == ys ? 0 : 1, re, rm);
1da177e4	144	}