arch/arm26/nwfpe/fpa11_cprt.c

   1 /*
   2     NetWinder Floating Point Emulator
   3     (c) Rebel.COM, 1998,1999
   4     (c) Philip Blundell, 1999
   5
   6     Direct questions, comments to Scott Bambrough <scottb@netwinder.org>
   7
   8     This program is free software; you can redistribute it and/or modify
   9     it under the terms of the GNU General Public License as published by
  10     the Free Software Foundation; either version 2 of the License, or
  11     (at your option) any later version.
  12
  13     This program 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
  16     GNU General Public License for more details.
  17
  18     You should have received a copy of the GNU General Public License
  19     along with this program; if not, write to the Free Software
  20     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  21 */
  22
  23 #include "fpa11.h"
  24 #include "milieu.h"
  25 #include "softfloat.h"
  26 #include "fpopcode.h"
  27 #include "fpa11.inl"
  28 #include "fpmodule.h"
  29 #include "fpmodule.inl"
  30
  31 extern flag floatx80_is_nan(floatx80);
  32 extern flag float64_is_nan( float64);
  33 extern flag float32_is_nan( float32);
  34
  35 void SetRoundingMode(const unsigned int opcode);
  36
  37 unsigned int PerformFLT(const unsigned int opcode);
  38 unsigned int PerformFIX(const unsigned int opcode);
  39
  40 static unsigned int
  41 PerformComparison(const unsigned int opcode);
  42
  43 unsigned int EmulateCPRT(const unsigned int opcode)
  44 {
  45   unsigned int nRc = 1;
  46
  47   //printk("EmulateCPRT(0x%08x)\n",opcode);
  48
  49   if (opcode & 0x800000)
  50   {
  51      /* This is some variant of a comparison (PerformComparison will
  52         sort out which one).  Since most of the other CPRT
  53         instructions are oddball cases of some sort or other it makes
  54         sense to pull this out into a fast path.  */
  55      return PerformComparison(opcode);
  56   }
  57
  58   /* Hint to GCC that we'd like a jump table rather than a load of CMPs */
  59   switch ((opcode & 0x700000) >> 20)
  60   {
  61     case  FLT_CODE >> 20: nRc = PerformFLT(opcode); break;
  62     case  FIX_CODE >> 20: nRc = PerformFIX(opcode); break;
  63
  64     case  WFS_CODE >> 20: writeFPSR(readRegister(getRd(opcode))); break;
  65     case  RFS_CODE >> 20: writeRegister(getRd(opcode),readFPSR()); break;
  66
  67 #if 0    /* We currently have no use for the FPCR, so there's no point
  68             in emulating it. */
  69     case  WFC_CODE >> 20: writeFPCR(readRegister(getRd(opcode)));
  70     case  RFC_CODE >> 20: writeRegister(getRd(opcode),readFPCR()); break;
  71 #endif
  72
  73     default: nRc = 0;
  74   }
  75
  76   return nRc;
  77 }
  78
  79 unsigned int PerformFLT(const unsigned int opcode)
  80 {
  81    FPA11 *fpa11 = GET_FPA11();
  82
  83    unsigned int nRc = 1;
  84    SetRoundingMode(opcode);
  85
  86    switch (opcode & MASK_ROUNDING_PRECISION)
  87    {
  88       case ROUND_SINGLE:
  89       {
  90         fpa11->fType[getFn(opcode)] = typeSingle;
  91         fpa11->fpreg[getFn(opcode)].fSingle =
  92            int32_to_float32(readRegister(getRd(opcode)));
  93       }
  94       break;
  95
  96       case ROUND_DOUBLE:
  97       {
  98         fpa11->fType[getFn(opcode)] = typeDouble;
  99         fpa11->fpreg[getFn(opcode)].fDouble =
 100             int32_to_float64(readRegister(getRd(opcode)));
 101       }
 102       break;
 103
 104       case ROUND_EXTENDED:
 105       {
 106         fpa11->fType[getFn(opcode)] = typeExtended;
 107         fpa11->fpreg[getFn(opcode)].fExtended =
 108            int32_to_floatx80(readRegister(getRd(opcode)));
 109       }
 110       break;
 111
 112       default: nRc = 0;
 113   }
 114
 115   return nRc;
 116 }
 117
 118 unsigned int PerformFIX(const unsigned int opcode)
 119 {
 120    FPA11 *fpa11 = GET_FPA11();
 121    unsigned int nRc = 1;
 122    unsigned int Fn = getFm(opcode);
 123
 124    SetRoundingMode(opcode);
 125
 126    switch (fpa11->fType[Fn])
 127    {
 128       case typeSingle:
 129       {
 130          writeRegister(getRd(opcode),
 131                        float32_to_int32(fpa11->fpreg[Fn].fSingle));
 132       }
 133       break;
 134
 135       case typeDouble:
 136       {
 137          writeRegister(getRd(opcode),
 138                        float64_to_int32(fpa11->fpreg[Fn].fDouble));
 139       }
 140       break;
 141
 142       case typeExtended:
 143       {
 144          writeRegister(getRd(opcode),
 145                        floatx80_to_int32(fpa11->fpreg[Fn].fExtended));
 146       }
 147       break;
 148
 149       default: nRc = 0;
 150   }
 151
 152   return nRc;
 153 }
 154
 155
 156 static unsigned int __inline__
 157 PerformComparisonOperation(floatx80 Fn, floatx80 Fm)
 158 {
 159    unsigned int flags = 0;
 160
 161    /* test for less than condition */
 162    if (floatx80_lt(Fn,Fm))
 163    {
 164       flags |= CC_NEGATIVE;
 165    }
 166
 167    /* test for equal condition */
 168    if (floatx80_eq(Fn,Fm))
 169    {
 170       flags |= CC_ZERO;
 171    }
 172
 173    /* test for greater than or equal condition */
 174    if (floatx80_lt(Fm,Fn))
 175    {
 176       flags |= CC_CARRY;
 177    }
 178
 179    writeConditionCodes(flags);
 180    return 1;
 181 }
 182
 183 /* This instruction sets the flags N, Z, C, V in the FPSR. */
 184
 185 static unsigned int PerformComparison(const unsigned int opcode)
 186 {
 187    FPA11 *fpa11 = GET_FPA11();
 188    unsigned int Fn, Fm;
 189    floatx80 rFn, rFm;
 190    int e_flag = opcode & 0x400000;      /* 1 if CxFE */
 191    int n_flag = opcode & 0x200000;      /* 1 if CNxx */
 192    unsigned int flags = 0;
 193
 194    //printk("PerformComparison(0x%08x)\n",opcode);
 195
 196    Fn = getFn(opcode);
 197    Fm = getFm(opcode);
 198
 199    /* Check for unordered condition and convert all operands to 80-bit
 200       format.
 201       ?? Might be some mileage in avoiding this conversion if possible.
 202       Eg, if both operands are 32-bit, detect this and do a 32-bit
 203       comparison (cheaper than an 80-bit one).  */
 204    switch (fpa11->fType[Fn])
 205    {
 206       case typeSingle:
 207         //printk("single.\n");
 208         if (float32_is_nan(fpa11->fpreg[Fn].fSingle))
 209            goto unordered;
 210         rFn = float32_to_floatx80(fpa11->fpreg[Fn].fSingle);
 211       break;
 212
 213       case typeDouble:
 214         //printk("double.\n");
 215         if (float64_is_nan(fpa11->fpreg[Fn].fDouble))
 216            goto unordered;
 217         rFn = float64_to_floatx80(fpa11->fpreg[Fn].fDouble);
 218       break;
 219
 220       case typeExtended:
 221         //printk("extended.\n");
 222         if (floatx80_is_nan(fpa11->fpreg[Fn].fExtended))
 223            goto unordered;
 224         rFn = fpa11->fpreg[Fn].fExtended;
 225       break;
 226
 227       default: return 0;
 228    }
 229
 230    if (CONSTANT_FM(opcode))
 231    {
 232      //printk("Fm is a constant: #%d.\n",Fm);
 233      rFm = getExtendedConstant(Fm);
 234      if (floatx80_is_nan(rFm))
 235         goto unordered;
 236    }
 237    else
 238    {
 239      //printk("Fm = r%d which contains a ",Fm);
 240       switch (fpa11->fType[Fm])
 241       {
 242          case typeSingle:
 243            //printk("single.\n");
 244            if (float32_is_nan(fpa11->fpreg[Fm].fSingle))
 245               goto unordered;
 246            rFm = float32_to_floatx80(fpa11->fpreg[Fm].fSingle);
 247          break;
 248
 249          case typeDouble:
 250            //printk("double.\n");
 251            if (float64_is_nan(fpa11->fpreg[Fm].fDouble))
 252               goto unordered;
 253            rFm = float64_to_floatx80(fpa11->fpreg[Fm].fDouble);
 254          break;
 255
 256          case typeExtended:
 257            //printk("extended.\n");
 258            if (floatx80_is_nan(fpa11->fpreg[Fm].fExtended))
 259               goto unordered;
 260            rFm = fpa11->fpreg[Fm].fExtended;
 261          break;
 262
 263          default: return 0;
 264       }
 265    }
 266
 267    if (n_flag)
 268    {
 269       rFm.high ^= 0x8000;
 270    }
 271
 272    return PerformComparisonOperation(rFn,rFm);
 273
 274  unordered:
 275    /* ?? The FPA data sheet is pretty vague about this, in particular
 276       about whether the non-E comparisons can ever raise exceptions.
 277       This implementation is based on a combination of what it says in
 278       the data sheet, observation of how the Acorn emulator actually
 279       behaves (and how programs expect it to) and guesswork.  */
 280    flags |= CC_OVERFLOW;
 281    flags &= ~(CC_ZERO | CC_NEGATIVE);
 282
 283    if (BIT_AC & readFPSR()) flags |= CC_CARRY;
 284
 285    if (e_flag) float_raise(float_flag_invalid);
 286
 287    writeConditionCodes(flags);
 288    return 1;
 289 }