95 lines
3.1 KiB
C++
Executable File
95 lines
3.1 KiB
C++
Executable File
/////////////////////////////////////////////////////////////////////////
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// $Id: ferr.cc,v 1.15 2009-02-08 17:29:34 sshwarts Exp $
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/////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2003 Stanislav Shwartsman
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// Written by Stanislav Shwartsman [sshwarts at sourceforge net]
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//
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// This library is free software; you can redistribute it and/or
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// modify it under the terms of the GNU Lesser General Public
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// License as published by the Free Software Foundation; either
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// version 2 of the License, or (at your option) any later version.
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//
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// This library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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// Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public
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// License along with this library; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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//
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/////////////////////////////////////////////////////////////////////////
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#define NEED_CPU_REG_SHORTCUTS 1
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#include "bochs.h"
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#include "cpu/cpu.h"
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#define LOG_THIS BX_CPU_THIS_PTR
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#if BX_SUPPORT_FPU
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#include "softfloat-specialize.h"
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void BX_CPU_C::FPU_stack_overflow(void)
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{
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/* The masked response */
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if (BX_CPU_THIS_PTR the_i387.is_IA_masked())
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{
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BX_CPU_THIS_PTR the_i387.FPU_push();
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BX_WRITE_FPU_REG(floatx80_default_nan, 0);
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}
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FPU_exception(FPU_EX_Stack_Overflow);
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}
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void BX_CPU_C::FPU_stack_underflow(int stnr, int pop_stack)
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{
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/* The masked response */
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if (BX_CPU_THIS_PTR the_i387.is_IA_masked())
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{
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BX_WRITE_FPU_REG(floatx80_default_nan, stnr);
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if (pop_stack)
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BX_CPU_THIS_PTR the_i387.FPU_pop();
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}
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FPU_exception(FPU_EX_Stack_Underflow);
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}
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/* Returns unmasked exceptions if occured */
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unsigned BX_CPU_C::FPU_exception(unsigned exception, bx_bool is_mem)
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{
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/* Extract only the bits which we use to set the status word */
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exception &= (FPU_SW_Exceptions_Mask);
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/* Set the corresponding exception bits */
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FPU_PARTIAL_STATUS |= exception;
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unsigned unmasked = FPU_PARTIAL_STATUS & ~FPU_CONTROL_WORD & FPU_CW_Exceptions_Mask;
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/* Set summary bits iff exception isn't masked */
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if (unmasked)
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FPU_PARTIAL_STATUS |= (FPU_SW_Summary | FPU_SW_Backward);
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if (exception & (FPU_SW_Stack_Fault | FPU_EX_Precision))
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{
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if (! (exception & FPU_SW_C1)) {
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/* This bit distinguishes over- from underflow for a stack fault,
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and roundup from round-down for precision loss. */
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FPU_PARTIAL_STATUS &= ~FPU_SW_C1;
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}
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}
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// If #P unmasked exception occured the result still has to be
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// written to the destination.
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unmasked &= ~FPU_CW_Precision;
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// If unmasked overflow or underflow occurs and destination is a memory
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// location, the TOS and destination operands remain unchanged and no
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// result is stored in the memory. If the destination is in the register
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// stack, adjusted resulting value is stored in the destination operand.
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if (! is_mem)
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unmasked &= ~(FPU_CW_Underflow | FPU_CW_Overflow);
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return unmasked;
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}
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#endif
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