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

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/* IEEE754 floating point arithmetic

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 * double precision: common utilities

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 */

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/*

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 * MIPS floating point support

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 * Copyright (C) 1994-2000 Algorithmics Ltd.

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 * Copyright (C) 2017 Imagination Technologies, Ltd.

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 * Author: Aleksandar Markovic <[email protected]>

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 */

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#include "ieee754dp.h"

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union ieee754dp ieee754dp_rint(union ieee754dp x)

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{

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	union ieee754dp ret;

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	u64 residue;

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	int sticky;

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	int round;

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	int odd;

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	COMPXDP;

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	ieee754_clearcx();

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	EXPLODEXDP;

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	FLUSHXDP;

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	if (xc == IEEE754_CLASS_SNAN)

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		return ieee754dp_nanxcpt(x);

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	if ((xc == IEEE754_CLASS_QNAN) ||

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	    (xc == IEEE754_CLASS_INF) ||

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	    (xc == IEEE754_CLASS_ZERO))

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		return x;

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	if (xe >= DP_FBITS)

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		return x;

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	if (xe < -1) {

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		residue = xm;

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		round = 0;

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		sticky = residue != 0;

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		xm = 0;

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	} else {

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		residue = xm << (64 - DP_FBITS + xe);

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		round = (residue >> 63) != 0;

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		sticky = (residue << 1) != 0;

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		xm >>= DP_FBITS - xe;

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	}

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	odd = (xm & 0x1) != 0x0;

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	switch (ieee754_csr.rm) {

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	case FPU_CSR_RN:	/* toward nearest */

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		if (round && (sticky || odd))

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			xm++;

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		break;

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	case FPU_CSR_RZ:	/* toward zero */

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		break;

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	case FPU_CSR_RU:	/* toward +infinity */

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		if ((round || sticky) && !xs)

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			xm++;

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		break;

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	case FPU_CSR_RD:	/* toward -infinity */

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		if ((round || sticky) && xs)

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			xm++;

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		break;

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	}

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	if (round || sticky)

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		ieee754_setcx(IEEE754_INEXACT);

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	ret = ieee754dp_flong(xm);

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	DPSIGN(ret) = xs;

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	return ret;

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}

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