cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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sp_rint.c (1497B)

      1// SPDX-License-Identifier: GPL-2.0-only
      2/* IEEE754 floating point arithmetic
      3 * single precision
      4 */
      5/*
      6 * MIPS floating point support
      7 * Copyright (C) 1994-2000 Algorithmics Ltd.
      8 * Copyright (C) 2017 Imagination Technologies, Ltd.
      9 * Author: Aleksandar Markovic <aleksandar.markovic@imgtec.com>
     10 */
     11
     12#include "ieee754sp.h"
     13
     14union ieee754sp ieee754sp_rint(union ieee754sp x)
     15{
     16	union ieee754sp ret;
     17	u32 residue;
     18	int sticky;
     19	int round;
     20	int odd;
     21
     22	COMPXDP;		/* <-- DP needed for 64-bit mantissa tmp */
     23
     24	ieee754_clearcx();
     25
     26	EXPLODEXSP;
     27	FLUSHXSP;
     28
     29	if (xc == IEEE754_CLASS_SNAN)
     30		return ieee754sp_nanxcpt(x);
     31
     32	if ((xc == IEEE754_CLASS_QNAN) ||
     33	    (xc == IEEE754_CLASS_INF) ||
     34	    (xc == IEEE754_CLASS_ZERO))
     35		return x;
     36
     37	if (xe >= SP_FBITS)
     38		return x;
     39
     40	if (xe < -1) {
     41		residue = xm;
     42		round = 0;
     43		sticky = residue != 0;
     44		xm = 0;
     45	} else {
     46		residue = xm << (xe + 1);
     47		residue <<= 31 - SP_FBITS;
     48		round = (residue >> 31) != 0;
     49		sticky = (residue << 1) != 0;
     50		xm >>= SP_FBITS - xe;
     51	}
     52
     53	odd = (xm & 0x1) != 0x0;
     54
     55	switch (ieee754_csr.rm) {
     56	case FPU_CSR_RN:	/* toward nearest */
     57		if (round && (sticky || odd))
     58			xm++;
     59		break;
     60	case FPU_CSR_RZ:	/* toward zero */
     61		break;
     62	case FPU_CSR_RU:	/* toward +infinity */
     63		if ((round || sticky) && !xs)
     64			xm++;
     65		break;
     66	case FPU_CSR_RD:	/* toward -infinity */
     67		if ((round || sticky) && xs)
     68			xm++;
     69		break;
     70	}
     71
     72	if (round || sticky)
     73		ieee754_setcx(IEEE754_INEXACT);
     74
     75	ret = ieee754sp_flong(xm);
     76	SPSIGN(ret) = xs;
     77
     78	return ret;
     79}