fpu/ferr.cc

   1 /////////////////////////////////////////////////////////////////////////
   2 // $Id: ferr.cc,v 1.8 2007/03/23 21:27:12 sshwarts Exp $
   3 /////////////////////////////////////////////////////////////////////////
   4 //
   5 //   Copyright (c) 2003 Stanislav Shwartsman
   6 //          Written by Stanislav Shwartsman [sshwarts at sourceforge net]
   7 //
   8 //  This library is free software; you can redistribute it and/or
   9 //  modify it under the terms of the GNU Lesser General Public
  10 //  License as published by the Free Software Foundation; either
  11 //  version 2 of the License, or (at your option) any later version.
  12 //
  13 //  This library is distributed in the hope that it will be useful,
  14 //  but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 //  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16 //  Lesser General Public License for more details.
  17 //
  18 //  You should have received a copy of the GNU Lesser General Public
  19 //  License along with this library; if not, write to the Free Software
  20 //  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  21 //
  22 /////////////////////////////////////////////////////////////////////////
  23
  24 #define NEED_CPU_REG_SHORTCUTS 1
  25 #include "bochs.h"
  26 #include "cpu/cpu.h"
  27 #define LOG_THIS BX_CPU_THIS_PTR
  28
  29 #if BX_SUPPORT_FPU
  30
  31 #include "softfloat-specialize.h"
  32
  33 void BX_CPU_C::FPU_stack_overflow(void)
  34 {
  35   /* The masked response */
  36   if (BX_CPU_THIS_PTR the_i387.is_IA_masked())
  37   {
  38       BX_CPU_THIS_PTR the_i387.FPU_push();
  39       BX_WRITE_FPU_REGISTER_AND_TAG(floatx80_default_nan, FPU_Tag_Special, 0);
  40   }
  41   FPU_exception(FPU_EX_Stack_Overflow);
  42 }
  43
  44 void BX_CPU_C::FPU_stack_underflow(int stnr, int pop_stack)
  45 {
  46   /* The masked response */
  47   if (BX_CPU_THIS_PTR the_i387.is_IA_masked())
  48   {
  49      BX_WRITE_FPU_REGISTER_AND_TAG(floatx80_default_nan, FPU_Tag_Special, stnr);
  50      if (pop_stack)
  51           BX_CPU_THIS_PTR the_i387.FPU_pop();
  52   }
  53   FPU_exception(FPU_EX_Stack_Underflow);
  54 }
  55
  56 /* Returns 1 if unmasked exception occured */
  57 int BX_CPU_C::FPU_exception(int exception)
  58 {
  59   int unmasked = 0;
  60
  61   /* Extract only the bits which we use to set the status word */
  62   exception &= (FPU_SW_Exceptions_Mask);
  63
  64   /* Set the corresponding exception bits */
  65   FPU_PARTIAL_STATUS |= exception;
  66
  67   /* Set summary bits iff exception isn't masked */
  68   if (FPU_PARTIAL_STATUS & ~FPU_CONTROL_WORD & FPU_CW_Exceptions_Mask)
  69   {
  70       FPU_PARTIAL_STATUS |= (FPU_SW_Summary | FPU_SW_Backward);
  71       unmasked = 1;
  72   }
  73
  74   if (exception & (FPU_SW_Stack_Fault | FPU_EX_Precision))
  75   {
  76       if (! (exception & FPU_SW_C1))
  77         /* This bit distinguishes over- from underflow for a stack fault,
  78              and roundup from round-down for precision loss. */
  79         FPU_PARTIAL_STATUS &= ~FPU_SW_C1;
  80   }
  81
  82   return unmasked;
  83 }
  84
  85 #endif