Archipelago » qemu

/*

    NetWinder Floating Point Emulator

    (c) Rebel.COM, 1998,1999

    (c) Philip Blundell, 1999

    Direct questions, comments to Scott Bambrough <scottb@netwinder.org>

    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation; either version 2 of the License, or

    (at your option) any later version.

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program; if not, write to the Free Software

    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include "fpa11.h"

#include "milieu.h"

#include "softfloat.h"

#include "fpopcode.h"

#include "fpa11.inl"

//#include "fpmodule.h"

//#include "fpmodule.inl"

extern flag floatx80_is_nan(floatx80);

extern flag float64_is_nan( float64);

extern flag float32_is_nan( float32);

void SetRoundingMode(const unsigned int opcode);

unsigned int PerformFLT(const unsigned int opcode);

unsigned int PerformFIX(const unsigned int opcode);

static unsigned int

PerformComparison(const unsigned int opcode);

unsigned int EmulateCPRT(const unsigned int opcode)

{

  unsigned int nRc = 1;

  //printk("EmulateCPRT(0x%08x)\n",opcode);

  if (opcode & 0x800000)

  {

     /* This is some variant of a comparison (PerformComparison will

        sort out which one).  Since most of the other CPRT

        instructions are oddball cases of some sort or other it makes

        sense to pull this out into a fast path.  */

     return PerformComparison(opcode);

  }

  /* Hint to GCC that we'd like a jump table rather than a load of CMPs */

  switch ((opcode & 0x700000) >> 20)

  {

    case  FLT_CODE >> 20: nRc = PerformFLT(opcode); break;

    case  FIX_CODE >> 20: nRc = PerformFIX(opcode); break;

    case  WFS_CODE >> 20: writeFPSR(readRegister(getRd(opcode))); break;

    case  RFS_CODE >> 20: writeRegister(getRd(opcode),readFPSR()); break;

#if 0    /* We currently have no use for the FPCR, so there's no point

            in emulating it. */

    case  WFC_CODE >> 20: writeFPCR(readRegister(getRd(opcode)));

    case  RFC_CODE >> 20: writeRegister(getRd(opcode),readFPCR()); break;

#endif

    default: nRc = 0;

  }

  return nRc;

}

unsigned int PerformFLT(const unsigned int opcode)

{

   FPA11 *fpa11 = GET_FPA11();

   unsigned int nRc = 1;

   SetRoundingMode(opcode);

   switch (opcode & MASK_ROUNDING_PRECISION)

   {

      case ROUND_SINGLE:

      {

        fpa11->fType[getFn(opcode)] = typeSingle;

        fpa11->fpreg[getFn(opcode)].fSingle =

           int32_to_float32(readRegister(getRd(opcode)));

      }

      break;

      case ROUND_DOUBLE:

      {

        fpa11->fType[getFn(opcode)] = typeDouble;

        fpa11->fpreg[getFn(opcode)].fDouble =

            int32_to_float64(readRegister(getRd(opcode)));

      }

      break;

      case ROUND_EXTENDED:

      {

        fpa11->fType[getFn(opcode)] = typeExtended;

        fpa11->fpreg[getFn(opcode)].fExtended =

           int32_to_floatx80(readRegister(getRd(opcode)));

      }

      break;

      default: nRc = 0;

  }

  return nRc;

}

unsigned int PerformFIX(const unsigned int opcode)

{

   FPA11 *fpa11 = GET_FPA11();

   unsigned int nRc = 1;

   unsigned int Fn = getFm(opcode);

   SetRoundingMode(opcode);

   switch (fpa11->fType[Fn])

   {

      case typeSingle:

      {

         writeRegister(getRd(opcode),

                       float32_to_int32(fpa11->fpreg[Fn].fSingle));

      }

      break;

      case typeDouble:

      {

         //printf("F%d is 0x%llx\n",Fn,fpa11->fpreg[Fn].fDouble);

         writeRegister(getRd(opcode),

                       float64_to_int32(fpa11->fpreg[Fn].fDouble));

      }

      break;

      case typeExtended:

      {

         writeRegister(getRd(opcode),

                       floatx80_to_int32(fpa11->fpreg[Fn].fExtended));

      }

      break;

      default: nRc = 0;

  }

  return nRc;

}

static unsigned int __inline__

PerformComparisonOperation(floatx80 Fn, floatx80 Fm)

{

   unsigned int flags = 0;

   /* test for less than condition */

   if (floatx80_lt(Fn,Fm))

   {

      flags |= CC_NEGATIVE;

   }

   /* test for equal condition */

   if (floatx80_eq(Fn,Fm))

   {

      flags |= CC_ZERO;

   }

   /* test for greater than or equal condition */

   if (floatx80_lt(Fm,Fn))

   {

      flags |= CC_CARRY;

   }

   writeConditionCodes(flags);

   return 1;

}

/* This instruction sets the flags N, Z, C, V in the FPSR. */

static unsigned int PerformComparison(const unsigned int opcode)

{

   FPA11 *fpa11 = GET_FPA11();

   unsigned int Fn, Fm;

   floatx80 rFn, rFm;

   int e_flag = opcode & 0x400000;        /* 1 if CxFE */

   int n_flag = opcode & 0x200000;        /* 1 if CNxx */

   unsigned int flags = 0;

   //printk("PerformComparison(0x%08x)\n",opcode);

   Fn = getFn(opcode);

   Fm = getFm(opcode);

   /* Check for unordered condition and convert all operands to 80-bit

      format.

      ?? Might be some mileage in avoiding this conversion if possible.

      Eg, if both operands are 32-bit, detect this and do a 32-bit

      comparison (cheaper than an 80-bit one).  */

   switch (fpa11->fType[Fn])

   {

      case typeSingle: 

        //printk("single.\n");

        if (float32_is_nan(fpa11->fpreg[Fn].fSingle))

           goto unordered;

        rFn = float32_to_floatx80(fpa11->fpreg[Fn].fSingle);

      break;

      case typeDouble: 

        //printk("double.\n");

        if (float64_is_nan(fpa11->fpreg[Fn].fDouble))

           goto unordered;

        rFn = float64_to_floatx80(fpa11->fpreg[Fn].fDouble);

      break;

      case typeExtended: 

        //printk("extended.\n");

        if (floatx80_is_nan(fpa11->fpreg[Fn].fExtended))

           goto unordered;

        rFn = fpa11->fpreg[Fn].fExtended;

      break;

      default: return 0;

   }

   if (CONSTANT_FM(opcode))

   {

     //printk("Fm is a constant: #%d.\n",Fm);

     rFm = getExtendedConstant(Fm);

     if (floatx80_is_nan(rFm))

        goto unordered;

   }

   else

   {

     //printk("Fm = r%d which contains a ",Fm);

      switch (fpa11->fType[Fm])

      {

         case typeSingle: 

           //printk("single.\n");

           if (float32_is_nan(fpa11->fpreg[Fm].fSingle))

              goto unordered;

           rFm = float32_to_floatx80(fpa11->fpreg[Fm].fSingle);

         break;

         case typeDouble: 

           //printk("double.\n");

           if (float64_is_nan(fpa11->fpreg[Fm].fDouble))

              goto unordered;

           rFm = float64_to_floatx80(fpa11->fpreg[Fm].fDouble);

         break;

         case typeExtended: 

           //printk("extended.\n");

           if (floatx80_is_nan(fpa11->fpreg[Fm].fExtended))

              goto unordered;

           rFm = fpa11->fpreg[Fm].fExtended;

         break;

         default: return 0;

      }

   }

   if (n_flag)

   {

      rFm.high ^= 0x8000;

   }

   return PerformComparisonOperation(rFn,rFm);

 unordered:

   /* ?? The FPA data sheet is pretty vague about this, in particular

      about whether the non-E comparisons can ever raise exceptions.

      This implementation is based on a combination of what it says in

      the data sheet, observation of how the Acorn emulator actually

      behaves (and how programs expect it to) and guesswork.  */

   flags |= CC_OVERFLOW;

   flags &= ~(CC_ZERO | CC_NEGATIVE);

   if (BIT_AC & readFPSR()) flags |= CC_CARRY;

   if (e_flag) float_raise(float_flag_invalid);

   writeConditionCodes(flags);

   return 1;

}