90 строки
1.9 KiB
C
90 строки
1.9 KiB
C
/* 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 <aleksandar.markovic@imgtec.com>
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*
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* This program is free software; you can distribute it and/or modify it
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* under the terms of the GNU General Public License (Version 2) as
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* published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program.
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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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