89 lines
2.1 KiB
C
89 lines
2.1 KiB
C
/*
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* This file is part of SIS.
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*
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* SIS, SPARC instruction simulator. Copyright (C) 1995 Jiri Gaisler, European
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* Space Agency
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*
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* This program is free software; you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 3 of the License, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that 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 for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, see <http://www.gnu.org/licenses/>.
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*
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*
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* This file implements the interface between the host and the simulated
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* FPU. IEEE trap handling is done as follows:
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* 1. In the host, all IEEE traps are masked
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* 2. After each simulated FPU instruction, check if any exception occured
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* by reading the exception bits from the host FPU status register
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* (get_accex()).
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* 3. Propagate any exceptions to the simulated FSR.
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* 4. Clear host exception bits
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*
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*
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*/
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#include "config.h"
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#include "sis.h"
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#include <fenv.h>
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/* This routine should return the accrued exceptions */
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int
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get_accex()
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{
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int fexc, accx;
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fexc = fetestexcept (FE_ALL_EXCEPT);
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accx = 0;
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if (fexc & FE_INEXACT)
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accx |= 1;
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if (fexc & FE_DIVBYZERO)
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accx |= 2;
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if (fexc & FE_UNDERFLOW)
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accx |= 4;
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if (fexc & FE_OVERFLOW)
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accx |= 8;
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if (fexc & FE_INVALID)
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accx |= 0x10;
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return(accx);
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}
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/* How to clear the accrued exceptions */
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void
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clear_accex()
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{
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feclearexcept (FE_ALL_EXCEPT);
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}
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/* How to map SPARC FSR onto the host */
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void
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set_fsr(fsr)
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uint32 fsr;
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{
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int fround;
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fsr >>= 30;
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switch (fsr) {
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case 0:
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fround = FE_TONEAREST;
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break;
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case 1:
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fround = FE_TOWARDZERO;
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break;
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case 2:
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fround = FE_UPWARD;
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break;
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case 3:
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fround = FE_DOWNWARD;
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break;
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}
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fesetround (fround);
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}
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