77 строки
1.9 KiB
C
77 строки
1.9 KiB
C
/* IEEE754 floating point arithmetic
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* single precision
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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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*
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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; if not, write to the Free Software Foundation, Inc.,
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* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
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#include "ieee754sp.h"
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#include "ieee754dp.h"
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union ieee754sp ieee754sp_fdp(union ieee754dp x)
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{
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u32 rm;
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COMPXDP;
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union ieee754sp nan;
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EXPLODEXDP;
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ieee754_clearcx();
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FLUSHXDP;
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switch (xc) {
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case IEEE754_CLASS_SNAN:
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ieee754_setcx(IEEE754_INVALID_OPERATION);
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return ieee754sp_nanxcpt(ieee754sp_indef());
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case IEEE754_CLASS_QNAN:
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nan = buildsp(xs, SP_EMAX + 1 + SP_EBIAS, (u32)
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(xm >> (DP_FBITS - SP_FBITS)));
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if (!ieee754sp_isnan(nan))
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nan = ieee754sp_indef();
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return ieee754sp_nanxcpt(nan);
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case IEEE754_CLASS_INF:
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return ieee754sp_inf(xs);
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case IEEE754_CLASS_ZERO:
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return ieee754sp_zero(xs);
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case IEEE754_CLASS_DNORM:
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/* can't possibly be sp representable */
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ieee754_setcx(IEEE754_UNDERFLOW);
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ieee754_setcx(IEEE754_INEXACT);
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if ((ieee754_csr.rm == FPU_CSR_RU && !xs) ||
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(ieee754_csr.rm == FPU_CSR_RD && xs))
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return ieee754sp_mind(xs);
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return ieee754sp_zero(xs);
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case IEEE754_CLASS_NORM:
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break;
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}
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/*
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* Convert from DP_FBITS to SP_FBITS+3 with sticky right shift.
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*/
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rm = (xm >> (DP_FBITS - (SP_FBITS + 3))) |
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((xm << (64 - (DP_FBITS - (SP_FBITS + 3)))) != 0);
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return ieee754sp_format(xs, xe, rm);
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}
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