fpa11_cpdo.c

上传linux-jx2410的源代码

/*
    NetWinder Floating Point Emulator
    (c) Rebel.COM, 1998,1999

    Direct questions, comments to Scott Bambrough <[e-mail]>

    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 "fpopcode.h"

unsigned int SingleCPDO(const unsigned int opcode);
unsigned int DoubleCPDO(const unsigned int opcode);
unsigned int ExtendedCPDO(const unsigned int opcode);

unsigned int EmulateCPDO(const unsigned int opcode)
{
   FPA11 *fpa11 = GET_FPA11();
   unsigned int Fd, nType, nDest, nRc = 1;
   
   //printk("EmulateCPDO(0x%08x)\n",opcode);

   /* Get the destination size.  If not valid let Linux perform
      an invalid instruction trap. */
   nDest = getDestinationSize(opcode);
   if (typeNone == nDest) return 0;
   
   SetRoundingMode(opcode);
     
   /* Compare the size of the operands in Fn and Fm.
      Choose the largest size and perform operations in that size,
      in order to make use of all the precision of the operands. 
      If Fm is a constant, we just grab a constant of a size 
      matching the size of the operand in Fn. */
   if (MONADIC_INSTRUCTION(opcode))
     nType = nDest;
   else
     nType = fpa11->fType[getFn(opcode)];
   
   if (!CONSTANT_FM(opcode))
   {
     register unsigned int Fm = getFm(opcode);
     if (nType < fpa11->fType[Fm])
     {
        nType = fpa11->fType[Fm];
     }
   }

   switch (nType)
   {
      case typeSingle   : nRc = SingleCPDO(opcode);   break;
      case typeDouble   : nRc = DoubleCPDO(opcode);   break;
      case typeExtended : nRc = ExtendedCPDO(opcode); break;
      default           : nRc = 0;
   }

   /* If the operation succeeded, check to see if the result in the
      destination register is the correct size.  If not force it
      to be. */
   Fd = getFd(opcode);
   nType = fpa11->fType[Fd];
   if ((0 != nRc) && (nDest != nType))
   {
     switch (nDest)
     {
       case typeSingle:
       {
         if (typeDouble == nType)
           fpa11->fpreg[Fd].fSingle = 
              float64_to_float32(fpa11->fpreg[Fd].fDouble);
         else
           fpa11->fpreg[Fd].fSingle = 
              floatx80_to_float32(fpa11->fpreg[Fd].fExtended);
       }
       break;
          
       case typeDouble:
       {
         if (typeSingle == nType)
           fpa11->fpreg[Fd].fDouble = 
              float32_to_float64(fpa11->fpreg[Fd].fSingle);
         else
           fpa11->fpreg[Fd].fDouble = 
              floatx80_to_float64(fpa11->fpreg[Fd].fExtended);
       }
       break;
          
       case typeExtended:
       {
         if (typeSingle == nType)
           fpa11->fpreg[Fd].fExtended = 
              float32_to_floatx80(fpa11->fpreg[Fd].fSingle);
         else
           fpa11->fpreg[Fd].fExtended = 
              float64_to_floatx80(fpa11->fpreg[Fd].fDouble);
       }
       break;
     }
     
     fpa11->fType[Fd] = nDest;
   }
   
   return nRc;
}