arch/arm/nwfpe/fpa11.c

   1 /*
   2     NetWinder Floating Point Emulator
   3     (c) Rebel.com, 1998-1999
   4
   5     Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
   6
   7     This program is free software; you can redistribute it and/or modify
   8     it under the terms of the GNU General Public License as published by
   9     the Free Software Foundation; either version 2 of the License, or
  10     (at your option) any later version.
  11
  12     This program is distributed in the hope that it will be useful,
  13     but WITHOUT ANY WARRANTY; without even the implied warranty of
  14     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15     GNU General Public License for more details.
  16
  17     You should have received a copy of the GNU General Public License
  18     along with this program; if not, write to the Free Software
  19     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  20 */
  21
  22 #include "config.h"
  23 #include "fpa11.h"
  24 #include "milieu.h"
  25 #include "fpopcode.h"
  26
  27 #include "fpmodule.h"
  28 #include "fpmodule.inl"
  29
  30 /* forward declarations */
  31 unsigned int EmulateCPDO(const unsigned int);
  32 unsigned int EmulateCPDT(const unsigned int);
  33 unsigned int EmulateCPRT(const unsigned int);
  34
  35 /* Emulator registers */
  36 FPA11 *fpa11;
  37
  38 /* Reset the FPA11 chip.  Called to initialize and reset the emulator. */
  39 void resetFPA11(void)
  40 {
  41   int i;
  42   /* initialize the registers */
  43   for (i=0;i<=7;i++)
  44   {
  45     fpa11->fpreg[i].fType = typeNone;
  46   }
  47
  48   /* FPSR: set system id to FP_EMULATOR, clear all other bits */
  49   fpa11->fpsr = FP_EMULATOR;
  50
  51   /* FPCR: set SB, AB and DA bits, clear all others */
  52 #if MAINTAIN_FPCR
  53   fpa11->fpcr = MASK_RESET;
  54 #endif
  55 }
  56
  57 void SetRoundingMode(const unsigned int opcode)
  58 {
  59 #if MAINTAIN_FPCR
  60    fpa11->fpcr &= ~MASK_ROUNDING_MODE;
  61 #endif
  62    switch (opcode & MASK_ROUNDING_MODE)
  63    {
  64       default:
  65       case ROUND_TO_NEAREST:
  66          float_rounding_mode = float_round_nearest_even;
  67 #if MAINTAIN_FPCR
  68          fpa11->fpcr |= ROUND_TO_NEAREST;
  69 #endif
  70       break;
  71
  72       case ROUND_TO_PLUS_INFINITY:
  73          float_rounding_mode = float_round_up;
  74 #if MAINTAIN_FPCR
  75          fpa11->fpcr |= ROUND_TO_PLUS_INFINITY;
  76 #endif
  77       break;
  78
  79       case ROUND_TO_MINUS_INFINITY:
  80          float_rounding_mode = float_round_down;
  81 #if MAINTAIN_FPCR
  82          fpa11->fpcr |= ROUND_TO_MINUS_INFINITY;
  83 #endif
  84       break;
  85
  86       case ROUND_TO_ZERO:
  87          float_rounding_mode = float_round_to_zero;
  88 #if MAINTAIN_FPCR
  89          fpa11->fpcr |= ROUND_TO_ZERO;
  90 #endif
  91       break;
  92   }
  93 }
  94
  95 void SetRoundingPrecision(const unsigned int opcode)
  96 {
  97 #if MAINTAIN_FPCR
  98    fpa11->fpcr &= ~MASK_ROUNDING_PRECISION;
  99 #endif
 100    switch (opcode & MASK_ROUNDING_PRECISION)
 101    {
 102       case ROUND_SINGLE:
 103          floatx80_rounding_precision = 32;
 104 #if MAINTAIN_FPCR
 105          fpa11->fpcr |= ROUND_SINGLE;
 106 #endif
 107       break;
 108
 109       case ROUND_DOUBLE:
 110          floatx80_rounding_precision = 64;
 111 #if MAINTAIN_FPCR
 112          fpa11->fpcr |= ROUND_DOUBLE;
 113 #endif
 114       break;
 115
 116       case ROUND_EXTENDED:
 117          floatx80_rounding_precision = 80;
 118 #if MAINTAIN_FPCR
 119          fpa11->fpcr |= ROUND_EXTENDED;
 120 #endif
 121       break;
 122
 123       default: floatx80_rounding_precision = 80;
 124   }
 125 }
 126
 127 /* Emulate the instruction in the opcode. */
 128 unsigned int EmulateAll(unsigned int opcode)
 129 {
 130   unsigned int nRc = 0;
 131
 132   if (fpa11->initflag == 0)             /* good place for __builtin_expect */
 133   {
 134     resetFPA11();
 135     SetRoundingMode(ROUND_TO_NEAREST);
 136     SetRoundingPrecision(ROUND_EXTENDED);
 137     fpa11->initflag = 1;
 138   }
 139
 140   if (TEST_OPCODE(opcode,MASK_CPRT))
 141   {
 142     /* Emulate conversion opcodes. */
 143     /* Emulate register transfer opcodes. */
 144     /* Emulate comparison opcodes. */
 145     nRc = EmulateCPRT(opcode);
 146   }
 147   else if (TEST_OPCODE(opcode,MASK_CPDO))
 148   {
 149     /* Emulate monadic arithmetic opcodes. */
 150     /* Emulate dyadic arithmetic opcodes. */
 151     nRc = EmulateCPDO(opcode);
 152   }
 153   else if (TEST_OPCODE(opcode,MASK_CPDT))
 154   {
 155     /* Emulate load/store opcodes. */
 156     /* Emulate load/store multiple opcodes. */
 157     nRc = EmulateCPDT(opcode);
 158   }
 159   else
 160   {
 161     /* Invalid instruction detected.  Return FALSE. */
 162     nRc = 0;
 163   }
 164
 165   return(nRc);
 166 }
 167
 168 #if 0
 169 unsigned int EmulateAll1(unsigned int opcode)
 170 {
 171   switch ((opcode >> 24) & 0xf)
 172   {
 173      case 0xc:
 174      case 0xd:
 175        if ((opcode >> 20) & 0x1)
 176        {
 177           switch ((opcode >> 8) & 0xf)
 178           {
 179              case 0x1: return PerformLDF(opcode); break;
 180              case 0x2: return PerformLFM(opcode); break;
 181              default: return 0;
 182           }
 183        }
 184        else
 185        {
 186           switch ((opcode >> 8) & 0xf)
 187           {
 188              case 0x1: return PerformSTF(opcode); break;
 189              case 0x2: return PerformSFM(opcode); break;
 190              default: return 0;
 191           }
 192       }
 193      break;
 194
 195      case 0xe:
 196        if (opcode & 0x10)
 197          return EmulateCPDO(opcode);
 198        else
 199          return EmulateCPRT(opcode);
 200      break;
 201
 202      default: return 0;
 203   }
 204 }
 205 #endif
 206