arch/mips/math-emu/sp_maddf.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * IEEE754 floating point arithmetic
  * single precision: MADDF.f (Fused Multiply Add)
  * MADDF.fmt: FPR[fd] = FPR[fd] + (FPR[fs] x FPR[ft])
  *
  * MIPS floating point support
  * Copyright (C) 2015 Imagination Technologies, Ltd.
  * Author: Markos Chandras <markos.chandras@imgtec.com>
  */

 #include "ieee754sp.h"


 static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
 				 union ieee754sp y, enum maddf_flags flags)
 {
 	int re;
 	int rs;
 	unsigned int rm;
 	u64 rm64;
 	u64 zm64;
 	int s;

 	COMPXSP;
 	COMPYSP;
 	COMPZSP;

 	EXPLODEXSP;
 	EXPLODEYSP;
 	EXPLODEZSP;

 	FLUSHXSP;
 	FLUSHYSP;
 	FLUSHZSP;

 	ieee754_clearcx();

 	rs = xs ^ ys;
 	if (flags & MADDF_NEGATE_PRODUCT)
 		rs ^= 1;
 	if (flags & MADDF_NEGATE_ADDITION)
 		zs ^= 1;

 	/*
 	 * Handle the cases when at least one of x, y or z is a NaN.
 	 * Order of precedence is sNaN, qNaN and z, x, y.
 	 */
 	if (zc == IEEE754_CLASS_SNAN)
 		return ieee754sp_nanxcpt(z);
 	if (xc == IEEE754_CLASS_SNAN)
 		return ieee754sp_nanxcpt(x);
 	if (yc == IEEE754_CLASS_SNAN)
 		return ieee754sp_nanxcpt(y);
 	if (zc == IEEE754_CLASS_QNAN)
 		return z;
 	if (xc == IEEE754_CLASS_QNAN)
 		return x;
 	if (yc == IEEE754_CLASS_QNAN)
 		return y;

 	if (zc == IEEE754_CLASS_DNORM)
 		SPDNORMZ;
 	/* ZERO z cases are handled separately below */

 	switch (CLPAIR(xc, yc)) {


 	/*
 	 * Infinity handling
 	 */
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
 		ieee754_setcx(IEEE754_INVALID_OPERATION);
 		return ieee754sp_indef();

 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
 		if ((zc == IEEE754_CLASS_INF) && (zs != rs)) {
 			/*
 			 * Cases of addition of infinities with opposite signs
 			 * or subtraction of infinities with same signs.
 			 */
 			ieee754_setcx(IEEE754_INVALID_OPERATION);
 			return ieee754sp_indef();
 		}
 		/*
 		 * z is here either not an infinity, or an infinity having the
 		 * same sign as product (x*y). The result must be an infinity,
 		 * and its sign is determined only by the sign of product (x*y).
 		 */
 		return ieee754sp_inf(rs);

 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
 	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
 		if (zc == IEEE754_CLASS_INF)
 			return ieee754sp_inf(zs);
 		if (zc == IEEE754_CLASS_ZERO) {
 			/* Handle cases +0 + (-0) and similar ones. */
 			if (zs == rs)
 				/*
 				 * Cases of addition of zeros of equal signs
 				 * or subtraction of zeroes of opposite signs.
 				 * The sign of the resulting zero is in any
 				 * such case determined only by the sign of z.
 				 */
 				return z;

 			return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD);
 		}
 		/* x*y is here 0, and z is not 0, so just return z */
 		return z;

 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
 		SPDNORMX;
 		fallthrough;
 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
 		if (zc == IEEE754_CLASS_INF)
 			return ieee754sp_inf(zs);
 		SPDNORMY;
 		break;

 	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
 		if (zc == IEEE754_CLASS_INF)
 			return ieee754sp_inf(zs);
 		SPDNORMX;
 		break;

 	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
 		if (zc == IEEE754_CLASS_INF)
 			return ieee754sp_inf(zs);
 		/* continue to real computations */
 	}

 	/* Finally get to do some computation */

 	/*
 	 * Do the multiplication bit first
 	 *
 	 * rm = xm * ym, re = xe + ye basically
 	 *
 	 * At this point xm and ym should have been normalized.
 	 */

 	/* rm = xm * ym, re = xe+ye basically */
 	assert(xm & SP_HIDDEN_BIT);
 	assert(ym & SP_HIDDEN_BIT);

 	re = xe + ye;

 	/* Multiple 24 bit xm and ym to give 48 bit results */
 	rm64 = (uint64_t)xm * ym;

 	/* Shunt to top of word */
 	rm64 = rm64 << 16;

 	/* Put explicit bit at bit 62 if necessary */
 	if ((int64_t) rm64 < 0) {
 		rm64 = rm64 >> 1;
 		re++;
 	}

 	assert(rm64 & (1 << 62));

 	if (zc == IEEE754_CLASS_ZERO) {
 		/*
 		 * Move explicit bit from bit 62 to bit 26 since the
 		 * ieee754sp_format code expects the mantissa to be
 		 * 27 bits wide (24 + 3 rounding bits).
 		 */
 		rm = XSPSRS64(rm64, (62 - 26));
 		return ieee754sp_format(rs, re, rm);
 	}

 	/* Move explicit bit from bit 23 to bit 62 */
 	zm64 = (uint64_t)zm << (62 - 23);
 	assert(zm64 & (1 << 62));

 	/* Make the exponents the same */
 	if (ze > re) {
 		/*
 		 * Have to shift r fraction right to align.
 		 */
 		s = ze - re;
 		rm64 = XSPSRS64(rm64, s);
 		re += s;
 	} else if (re > ze) {
 		/*
 		 * Have to shift z fraction right to align.
 		 */
 		s = re - ze;
 		zm64 = XSPSRS64(zm64, s);
 		ze += s;
 	}
 	assert(ze == re);
 	assert(ze <= SP_EMAX);

 	/* Do the addition */
 	if (zs == rs) {
 		/*
 		 * Generate 64 bit result by adding two 63 bit numbers
 		 * leaving result in zm64, zs and ze.
 		 */
 		zm64 = zm64 + rm64;
 		if ((int64_t)zm64 < 0) {	/* carry out */
 			zm64 = XSPSRS1(zm64);
 			ze++;
 		}
 	} else {
 		if (zm64 >= rm64) {
 			zm64 = zm64 - rm64;
 		} else {
 			zm64 = rm64 - zm64;
 			zs = rs;
 		}
 		if (zm64 == 0)
 			return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD);

 		/*
 		 * Put explicit bit at bit 62 if necessary.
 		 */
 		while ((zm64 >> 62) == 0) {
 			zm64 <<= 1;
 			ze--;
 		}
 	}

 	/*
 	 * Move explicit bit from bit 62 to bit 26 since the
 	 * ieee754sp_format code expects the mantissa to be
 	 * 27 bits wide (24 + 3 rounding bits).
 	 */
 	zm = XSPSRS64(zm64, (62 - 26));

 	return ieee754sp_format(zs, ze, zm);
 }

 union ieee754sp ieee754sp_maddf(union ieee754sp z, union ieee754sp x,
 				union ieee754sp y)
 {
 	return _sp_maddf(z, x, y, 0);
 }

 union ieee754sp ieee754sp_msubf(union ieee754sp z, union ieee754sp x,
 				union ieee754sp y)
 {
 	return _sp_maddf(z, x, y, MADDF_NEGATE_PRODUCT);
 }

 union ieee754sp ieee754sp_madd(union ieee754sp z, union ieee754sp x,
 				union ieee754sp y)
 {
 	return _sp_maddf(z, x, y, 0);
 }

 union ieee754sp ieee754sp_msub(union ieee754sp z, union ieee754sp x,
 				union ieee754sp y)
 {
 	return _sp_maddf(z, x, y, MADDF_NEGATE_ADDITION);
 }

 union ieee754sp ieee754sp_nmadd(union ieee754sp z, union ieee754sp x,
 				union ieee754sp y)
 {
 	return _sp_maddf(z, x, y, MADDF_NEGATE_PRODUCT|MADDF_NEGATE_ADDITION);
 }

 union ieee754sp ieee754sp_nmsub(union ieee754sp z, union ieee754sp x,
 				union ieee754sp y)
 {
 	return _sp_maddf(z, x, y, MADDF_NEGATE_PRODUCT);
 }
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* IEEE754 floating point arithmetic
	* single precision: MADDF.f (Fused Multiply Add)
	* MADDF.fmt: FPR[fd] = FPR[fd] + (FPR[fs] x FPR[ft])
	*
	* MIPS floating point support
	* Copyright (C) 2015 Imagination Technologies, Ltd.
	* Author: Markos Chandras <markos.chandras@imgtec.com>
	*/

	#include "ieee754sp.h"


	static union ieee754sp _sp_maddf(union ieee754sp z, union ieee754sp x,
	union ieee754sp y, enum maddf_flags flags)
	{
	int re;
	int rs;
	unsigned int rm;
	u64 rm64;
	u64 zm64;
	int s;

	COMPXSP;
	COMPYSP;
	COMPZSP;

	EXPLODEXSP;
	EXPLODEYSP;
	EXPLODEZSP;

	FLUSHXSP;
	FLUSHYSP;
	FLUSHZSP;

	ieee754_clearcx();

	rs = xs ^ ys;
	if (flags & MADDF_NEGATE_PRODUCT)
	rs ^= 1;
	if (flags & MADDF_NEGATE_ADDITION)
	zs ^= 1;

	/*
	* Handle the cases when at least one of x, y or z is a NaN.
	* Order of precedence is sNaN, qNaN and z, x, y.
	*/
	if (zc == IEEE754_CLASS_SNAN)
	return ieee754sp_nanxcpt(z);
	if (xc == IEEE754_CLASS_SNAN)
	return ieee754sp_nanxcpt(x);
	if (yc == IEEE754_CLASS_SNAN)
	return ieee754sp_nanxcpt(y);
	if (zc == IEEE754_CLASS_QNAN)
	return z;
	if (xc == IEEE754_CLASS_QNAN)
	return x;
	if (yc == IEEE754_CLASS_QNAN)
	return y;

	if (zc == IEEE754_CLASS_DNORM)
	SPDNORMZ;
	/* ZERO z cases are handled separately below */

	switch (CLPAIR(xc, yc)) {


	/*
	* Infinity handling
	*/
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_ZERO):
	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_INF):
	ieee754_setcx(IEEE754_INVALID_OPERATION);
	return ieee754sp_indef();

	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_INF):
	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_INF):
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_NORM):
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_DNORM):
	case CLPAIR(IEEE754_CLASS_INF, IEEE754_CLASS_INF):
	if ((zc == IEEE754_CLASS_INF) && (zs != rs)) {
	/*
	* Cases of addition of infinities with opposite signs
	* or subtraction of infinities with same signs.
	*/
	ieee754_setcx(IEEE754_INVALID_OPERATION);
	return ieee754sp_indef();
	}
	/*
	* z is here either not an infinity, or an infinity having the
	* same sign as product (x*y). The result must be an infinity,
	* and its sign is determined only by the sign of product (x*y).
	*/
	return ieee754sp_inf(rs);

	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_ZERO):
	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_NORM):
	case CLPAIR(IEEE754_CLASS_ZERO, IEEE754_CLASS_DNORM):
	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_ZERO):
	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_ZERO):
	if (zc == IEEE754_CLASS_INF)
	return ieee754sp_inf(zs);
	if (zc == IEEE754_CLASS_ZERO) {
	/* Handle cases +0 + (-0) and similar ones. */
	if (zs == rs)
	/*
	* Cases of addition of zeros of equal signs
	* or subtraction of zeroes of opposite signs.
	* The sign of the resulting zero is in any
	* such case determined only by the sign of z.
	*/
	return z;

	return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD);
	}
	/* xy is here 0, and z is not 0, so just return z /
	return z;

	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_DNORM):
	SPDNORMX;
	fallthrough;
	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_DNORM):
	if (zc == IEEE754_CLASS_INF)
	return ieee754sp_inf(zs);
	SPDNORMY;
	break;

	case CLPAIR(IEEE754_CLASS_DNORM, IEEE754_CLASS_NORM):
	if (zc == IEEE754_CLASS_INF)
	return ieee754sp_inf(zs);
	SPDNORMX;
	break;

	case CLPAIR(IEEE754_CLASS_NORM, IEEE754_CLASS_NORM):
	if (zc == IEEE754_CLASS_INF)
	return ieee754sp_inf(zs);
	/* continue to real computations */
	}

	/* Finally get to do some computation */

	/*
	* Do the multiplication bit first
	*
	* rm = xm * ym, re = xe + ye basically
	*
	* At this point xm and ym should have been normalized.
	*/

	/* rm = xm * ym, re = xe+ye basically */
	assert(xm & SP_HIDDEN_BIT);
	assert(ym & SP_HIDDEN_BIT);

	re = xe + ye;

	/* Multiple 24 bit xm and ym to give 48 bit results */
	rm64 = (uint64_t)xm * ym;

	/* Shunt to top of word */
	rm64 = rm64 << 16;

	/* Put explicit bit at bit 62 if necessary */
	if ((int64_t) rm64 < 0) {
	rm64 = rm64 >> 1;
	re++;
	}

	assert(rm64 & (1 << 62));

	if (zc == IEEE754_CLASS_ZERO) {
	/*
	* Move explicit bit from bit 62 to bit 26 since the
	* ieee754sp_format code expects the mantissa to be
	* 27 bits wide (24 + 3 rounding bits).
	*/
	rm = XSPSRS64(rm64, (62 - 26));
	return ieee754sp_format(rs, re, rm);
	}

	/* Move explicit bit from bit 23 to bit 62 */
	zm64 = (uint64_t)zm << (62 - 23);
	assert(zm64 & (1 << 62));

	/* Make the exponents the same */
	if (ze > re) {
	/*
	* Have to shift r fraction right to align.
	*/
	s = ze - re;
	rm64 = XSPSRS64(rm64, s);
	re += s;
	} else if (re > ze) {
	/*
	* Have to shift z fraction right to align.
	*/
	s = re - ze;
	zm64 = XSPSRS64(zm64, s);
	ze += s;
	}
	assert(ze == re);
	assert(ze <= SP_EMAX);

	/* Do the addition */
	if (zs == rs) {
	/*
	* Generate 64 bit result by adding two 63 bit numbers
	* leaving result in zm64, zs and ze.
	*/
	zm64 = zm64 + rm64;
	if ((int64_t)zm64 < 0) { /* carry out */
	zm64 = XSPSRS1(zm64);
	ze++;
	}
	} else {
	if (zm64 >= rm64) {
	zm64 = zm64 - rm64;
	} else {
	zm64 = rm64 - zm64;
	zs = rs;
	}
	if (zm64 == 0)
	return ieee754sp_zero(ieee754_csr.rm == FPU_CSR_RD);

	/*
	* Put explicit bit at bit 62 if necessary.
	*/
	while ((zm64 >> 62) == 0) {
	zm64 <<= 1;
	ze--;
	}
	}

	/*
	* Move explicit bit from bit 62 to bit 26 since the
	* ieee754sp_format code expects the mantissa to be
	* 27 bits wide (24 + 3 rounding bits).
	*/
	zm = XSPSRS64(zm64, (62 - 26));

	return ieee754sp_format(zs, ze, zm);
	}

	union ieee754sp ieee754sp_maddf(union ieee754sp z, union ieee754sp x,
	union ieee754sp y)
	{
	return _sp_maddf(z, x, y, 0);
	}

	union ieee754sp ieee754sp_msubf(union ieee754sp z, union ieee754sp x,
	union ieee754sp y)
	{
	return _sp_maddf(z, x, y, MADDF_NEGATE_PRODUCT);
	}

	union ieee754sp ieee754sp_madd(union ieee754sp z, union ieee754sp x,
	union ieee754sp y)
	{
	return _sp_maddf(z, x, y, 0);
	}

	union ieee754sp ieee754sp_msub(union ieee754sp z, union ieee754sp x,
	union ieee754sp y)
	{
	return _sp_maddf(z, x, y, MADDF_NEGATE_ADDITION);
	}

	union ieee754sp ieee754sp_nmadd(union ieee754sp z, union ieee754sp x,
	union ieee754sp y)
	{
	return _sp_maddf(z, x, y, MADDF_NEGATE_PRODUCT\|MADDF_NEGATE_ADDITION);
	}

	union ieee754sp ieee754sp_nmsub(union ieee754sp z, union ieee754sp x,
	union ieee754sp y)
	{
	return _sp_maddf(z, x, y, MADDF_NEGATE_PRODUCT);
	}