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torvalds
GitHub Repository: torvalds/linux
 Path: blob/master/arch/mips/math-emu/dp_fmax.c
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// SPDX-License-Identifier: GPL-2.0-only

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/*

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 * IEEE754 floating point arithmetic

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 * double precision: MIN{,A}.f

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 * MIN : Scalar Floating-Point Minimum

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 * MINA: Scalar Floating-Point argument with Minimum Absolute Value

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 *

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 * MIN.D : FPR[fd] = minNum(FPR[fs],FPR[ft])

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 * MINA.D: FPR[fd] = maxNumMag(FPR[fs],FPR[ft])

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 *

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 * MIPS floating point support

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 * Copyright (C) 2015 Imagination Technologies, Ltd.

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 * Author: Markos Chandras <[email protected]>

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 */

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#include "ieee754dp.h"

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union ieee754dp ieee754dp_fmax(union ieee754dp x, union ieee754dp y)

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{

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	COMPXDP;

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	COMPYDP;

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	EXPLODEXDP;

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	EXPLODEYDP;

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	FLUSHXDP;

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	FLUSHYDP;

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	ieee754_clearcx();

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	switch (CLPAIR(xc, yc)) {

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):

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		return ieee754dp_nanxcpt(y);

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):

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		return ieee754dp_nanxcpt(x);

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	/*

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	 * Quiet NaN handling

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	 */

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	/*

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	 *    The case of both inputs quiet NaNs

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	 */

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):

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		return x;

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	/*

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	 *    The cases of exactly one input quiet NaN (numbers

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	 *    are here preferred as returned values to NaNs)

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	 */

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):

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		return x;

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):

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		return y;

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	/*

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	 * Infinity and zero handling

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	 */

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):

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		return xs ? y : x;

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):

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		return ys ? x : y;

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):

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		return ieee754dp_zero(xs & ys);

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):

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		DPDNORMX;

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		fallthrough;

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):

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		DPDNORMY;

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		break;

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):

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		DPDNORMX;

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	}

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	/* Finally get to do some computation */

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	assert(xm & DP_HIDDEN_BIT);

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	assert(ym & DP_HIDDEN_BIT);

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	/* Compare signs */

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	if (xs > ys)

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		return y;

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	else if (xs < ys)

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		return x;

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	/* Signs of inputs are equal, let's compare exponents */

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	if (xs == 0) {

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		/* Inputs are both positive */

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		if (xe > ye)

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			return x;

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		else if (xe < ye)

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			return y;

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	} else {

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		/* Inputs are both negative */

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		if (xe > ye)

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			return y;

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		else if (xe < ye)

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			return x;

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	}

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	/* Signs and exponents of inputs are equal, let's compare mantissas */

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	if (xs == 0) {

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		/* Inputs are both positive, with equal signs and exponents */

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		if (xm <= ym)

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			return y;

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		return x;

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	}

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	/* Inputs are both negative, with equal signs and exponents */

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	if (xm <= ym)

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		return x;

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	return y;

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}

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union ieee754dp ieee754dp_fmaxa(union ieee754dp x, union ieee754dp y)

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{

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	COMPXDP;

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	COMPYDP;

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	EXPLODEXDP;

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	EXPLODEYDP;

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	FLUSHXDP;

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	FLUSHYDP;

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	ieee754_clearcx();

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	switch (CLPAIR(xc, yc)) {

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_SNAN):

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		return ieee754dp_nanxcpt(y);

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_SNAN):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_QNAN):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_ZERO):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_NORM):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_DNORM):

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	case CLPAIR(IEEE754_CLASS_SNAN, IEEE754_CLASS_INF):

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		return ieee754dp_nanxcpt(x);

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	/*

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	 * Quiet NaN handling

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	 */

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	/*

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	 *    The case of both inputs quiet NaNs

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	 */

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_QNAN):

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		return x;

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	/*

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	 *    The cases of exactly one input quiet NaN (numbers

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	 *    are here preferred as returned values to NaNs)

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	 */

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_QNAN):

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_QNAN):

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_QNAN):

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_QNAN):

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		return x;

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_ZERO):

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_NORM):

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_DNORM):

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	case CLPAIR(IEEE754_CLASS_QNAN, IEEE754_CLASS_INF):

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		return y;

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	/*

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	 * Infinity and zero handling

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	 */

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):

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		return ieee754dp_inf(xs & ys);

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):

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	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):

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		return x;

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):

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		return y;

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	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):

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		return ieee754dp_zero(xs & ys);

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):

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		DPDNORMX;

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		fallthrough;

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	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):

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		DPDNORMY;

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		break;

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	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):

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		DPDNORMX;

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	}

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	/* Finally get to do some computation */

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	assert(xm & DP_HIDDEN_BIT);

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	assert(ym & DP_HIDDEN_BIT);

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	/* Compare exponent */

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	if (xe > ye)

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		return x;

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	else if (xe < ye)

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		return y;

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	/* Compare mantissa */

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	if (xm < ym)

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		return y;

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	else if (xm > ym)

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		return x;

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	else if (xs == 0)

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		return x;

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	return y;

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}

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