Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* |
| 2 | NetWinder Floating Point Emulator |
| 3 | (c) Rebel.COM, 1998,1999 |
| 4 | (c) Philip Blundell, 1999, 2001 |
| 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 <linux/config.h> |
| 24 | #include "fpa11.h" |
| 25 | #include "fpopcode.h" |
| 26 | #include "fpa11.inl" |
| 27 | #include "fpmodule.h" |
| 28 | #include "fpmodule.inl" |
| 29 | |
| 30 | #ifdef CONFIG_FPE_NWFPE_XP |
| 31 | extern flag floatx80_is_nan(floatx80); |
| 32 | #endif |
| 33 | extern flag float64_is_nan(float64); |
| 34 | extern flag float32_is_nan(float32); |
| 35 | |
| 36 | void SetRoundingMode(const unsigned int opcode); |
| 37 | |
| 38 | unsigned int PerformFLT(const unsigned int opcode); |
| 39 | unsigned int PerformFIX(const unsigned int opcode); |
| 40 | |
| 41 | static unsigned int PerformComparison(const unsigned int opcode); |
| 42 | |
| 43 | unsigned int EmulateCPRT(const unsigned int opcode) |
| 44 | { |
| 45 | |
| 46 | if (opcode & 0x800000) { |
| 47 | /* This is some variant of a comparison (PerformComparison |
| 48 | will sort out which one). Since most of the other CPRT |
| 49 | instructions are oddball cases of some sort or other it |
| 50 | makes sense to pull this out into a fast path. */ |
| 51 | return PerformComparison(opcode); |
| 52 | } |
| 53 | |
| 54 | /* Hint to GCC that we'd like a jump table rather than a load of CMPs */ |
| 55 | switch ((opcode & 0x700000) >> 20) { |
| 56 | case FLT_CODE >> 20: |
| 57 | return PerformFLT(opcode); |
| 58 | break; |
| 59 | case FIX_CODE >> 20: |
| 60 | return PerformFIX(opcode); |
| 61 | break; |
| 62 | |
| 63 | case WFS_CODE >> 20: |
| 64 | writeFPSR(readRegister(getRd(opcode))); |
| 65 | break; |
| 66 | case RFS_CODE >> 20: |
| 67 | writeRegister(getRd(opcode), readFPSR()); |
| 68 | break; |
| 69 | |
| 70 | default: |
| 71 | return 0; |
| 72 | } |
| 73 | |
| 74 | return 1; |
| 75 | } |
| 76 | |
| 77 | unsigned int PerformFLT(const unsigned int opcode) |
| 78 | { |
| 79 | FPA11 *fpa11 = GET_FPA11(); |
| 80 | SetRoundingMode(opcode); |
| 81 | SetRoundingPrecision(opcode); |
| 82 | |
| 83 | switch (opcode & MASK_ROUNDING_PRECISION) { |
| 84 | case ROUND_SINGLE: |
| 85 | { |
| 86 | fpa11->fType[getFn(opcode)] = typeSingle; |
| 87 | fpa11->fpreg[getFn(opcode)].fSingle = int32_to_float32(readRegister(getRd(opcode))); |
| 88 | } |
| 89 | break; |
| 90 | |
| 91 | case ROUND_DOUBLE: |
| 92 | { |
| 93 | fpa11->fType[getFn(opcode)] = typeDouble; |
| 94 | fpa11->fpreg[getFn(opcode)].fDouble = int32_to_float64(readRegister(getRd(opcode))); |
| 95 | } |
| 96 | break; |
| 97 | |
| 98 | #ifdef CONFIG_FPE_NWFPE_XP |
| 99 | case ROUND_EXTENDED: |
| 100 | { |
| 101 | fpa11->fType[getFn(opcode)] = typeExtended; |
| 102 | fpa11->fpreg[getFn(opcode)].fExtended = int32_to_floatx80(readRegister(getRd(opcode))); |
| 103 | } |
| 104 | break; |
| 105 | #endif |
| 106 | |
| 107 | default: |
| 108 | return 0; |
| 109 | } |
| 110 | |
| 111 | return 1; |
| 112 | } |
| 113 | |
| 114 | unsigned int PerformFIX(const unsigned int opcode) |
| 115 | { |
| 116 | FPA11 *fpa11 = GET_FPA11(); |
| 117 | unsigned int Fn = getFm(opcode); |
| 118 | |
| 119 | SetRoundingMode(opcode); |
| 120 | |
| 121 | switch (fpa11->fType[Fn]) { |
| 122 | case typeSingle: |
| 123 | { |
| 124 | writeRegister(getRd(opcode), float32_to_int32(fpa11->fpreg[Fn].fSingle)); |
| 125 | } |
| 126 | break; |
| 127 | |
| 128 | case typeDouble: |
| 129 | { |
| 130 | writeRegister(getRd(opcode), float64_to_int32(fpa11->fpreg[Fn].fDouble)); |
| 131 | } |
| 132 | break; |
| 133 | |
| 134 | #ifdef CONFIG_FPE_NWFPE_XP |
| 135 | case typeExtended: |
| 136 | { |
| 137 | writeRegister(getRd(opcode), floatx80_to_int32(fpa11->fpreg[Fn].fExtended)); |
| 138 | } |
| 139 | break; |
| 140 | #endif |
| 141 | |
| 142 | default: |
| 143 | return 0; |
| 144 | } |
| 145 | |
| 146 | return 1; |
| 147 | } |
| 148 | |
| 149 | /* This instruction sets the flags N, Z, C, V in the FPSR. */ |
| 150 | static unsigned int PerformComparison(const unsigned int opcode) |
| 151 | { |
| 152 | FPA11 *fpa11 = GET_FPA11(); |
| 153 | unsigned int Fn = getFn(opcode), Fm = getFm(opcode); |
| 154 | int e_flag = opcode & 0x400000; /* 1 if CxFE */ |
| 155 | int n_flag = opcode & 0x200000; /* 1 if CNxx */ |
| 156 | unsigned int flags = 0; |
| 157 | |
| 158 | #ifdef CONFIG_FPE_NWFPE_XP |
| 159 | floatx80 rFn, rFm; |
| 160 | |
| 161 | /* Check for unordered condition and convert all operands to 80-bit |
| 162 | format. |
| 163 | ?? Might be some mileage in avoiding this conversion if possible. |
| 164 | Eg, if both operands are 32-bit, detect this and do a 32-bit |
| 165 | comparison (cheaper than an 80-bit one). */ |
| 166 | switch (fpa11->fType[Fn]) { |
| 167 | case typeSingle: |
| 168 | //printk("single.\n"); |
| 169 | if (float32_is_nan(fpa11->fpreg[Fn].fSingle)) |
| 170 | goto unordered; |
| 171 | rFn = float32_to_floatx80(fpa11->fpreg[Fn].fSingle); |
| 172 | break; |
| 173 | |
| 174 | case typeDouble: |
| 175 | //printk("double.\n"); |
| 176 | if (float64_is_nan(fpa11->fpreg[Fn].fDouble)) |
| 177 | goto unordered; |
| 178 | rFn = float64_to_floatx80(fpa11->fpreg[Fn].fDouble); |
| 179 | break; |
| 180 | |
| 181 | case typeExtended: |
| 182 | //printk("extended.\n"); |
| 183 | if (floatx80_is_nan(fpa11->fpreg[Fn].fExtended)) |
| 184 | goto unordered; |
| 185 | rFn = fpa11->fpreg[Fn].fExtended; |
| 186 | break; |
| 187 | |
| 188 | default: |
| 189 | return 0; |
| 190 | } |
| 191 | |
| 192 | if (CONSTANT_FM(opcode)) { |
| 193 | //printk("Fm is a constant: #%d.\n",Fm); |
| 194 | rFm = getExtendedConstant(Fm); |
| 195 | if (floatx80_is_nan(rFm)) |
| 196 | goto unordered; |
| 197 | } else { |
| 198 | //printk("Fm = r%d which contains a ",Fm); |
| 199 | switch (fpa11->fType[Fm]) { |
| 200 | case typeSingle: |
| 201 | //printk("single.\n"); |
| 202 | if (float32_is_nan(fpa11->fpreg[Fm].fSingle)) |
| 203 | goto unordered; |
| 204 | rFm = float32_to_floatx80(fpa11->fpreg[Fm].fSingle); |
| 205 | break; |
| 206 | |
| 207 | case typeDouble: |
| 208 | //printk("double.\n"); |
| 209 | if (float64_is_nan(fpa11->fpreg[Fm].fDouble)) |
| 210 | goto unordered; |
| 211 | rFm = float64_to_floatx80(fpa11->fpreg[Fm].fDouble); |
| 212 | break; |
| 213 | |
| 214 | case typeExtended: |
| 215 | //printk("extended.\n"); |
| 216 | if (floatx80_is_nan(fpa11->fpreg[Fm].fExtended)) |
| 217 | goto unordered; |
| 218 | rFm = fpa11->fpreg[Fm].fExtended; |
| 219 | break; |
| 220 | |
| 221 | default: |
| 222 | return 0; |
| 223 | } |
| 224 | } |
| 225 | |
| 226 | if (n_flag) |
| 227 | rFm.high ^= 0x8000; |
| 228 | |
| 229 | /* test for less than condition */ |
| 230 | if (floatx80_lt(rFn, rFm)) |
| 231 | flags |= CC_NEGATIVE; |
| 232 | |
| 233 | /* test for equal condition */ |
| 234 | if (floatx80_eq(rFn, rFm)) |
| 235 | flags |= CC_ZERO; |
| 236 | |
| 237 | /* test for greater than or equal condition */ |
| 238 | if (floatx80_lt(rFm, rFn)) |
| 239 | flags |= CC_CARRY; |
| 240 | |
| 241 | #else |
| 242 | if (CONSTANT_FM(opcode)) { |
| 243 | /* Fm is a constant. Do the comparison in whatever precision |
| 244 | Fn happens to be stored in. */ |
| 245 | if (fpa11->fType[Fn] == typeSingle) { |
| 246 | float32 rFm = getSingleConstant(Fm); |
| 247 | float32 rFn = fpa11->fpreg[Fn].fSingle; |
| 248 | |
| 249 | if (float32_is_nan(rFn)) |
| 250 | goto unordered; |
| 251 | |
| 252 | if (n_flag) |
| 253 | rFm ^= 0x80000000; |
| 254 | |
| 255 | /* test for less than condition */ |
| 256 | if (float32_lt_nocheck(rFn, rFm)) |
| 257 | flags |= CC_NEGATIVE; |
| 258 | |
| 259 | /* test for equal condition */ |
| 260 | if (float32_eq_nocheck(rFn, rFm)) |
| 261 | flags |= CC_ZERO; |
| 262 | |
| 263 | /* test for greater than or equal condition */ |
| 264 | if (float32_lt_nocheck(rFm, rFn)) |
| 265 | flags |= CC_CARRY; |
| 266 | } else { |
| 267 | float64 rFm = getDoubleConstant(Fm); |
| 268 | float64 rFn = fpa11->fpreg[Fn].fDouble; |
| 269 | |
| 270 | if (float64_is_nan(rFn)) |
| 271 | goto unordered; |
| 272 | |
| 273 | if (n_flag) |
| 274 | rFm ^= 0x8000000000000000ULL; |
| 275 | |
| 276 | /* test for less than condition */ |
| 277 | if (float64_lt_nocheck(rFn, rFm)) |
| 278 | flags |= CC_NEGATIVE; |
| 279 | |
| 280 | /* test for equal condition */ |
| 281 | if (float64_eq_nocheck(rFn, rFm)) |
| 282 | flags |= CC_ZERO; |
| 283 | |
| 284 | /* test for greater than or equal condition */ |
| 285 | if (float64_lt_nocheck(rFm, rFn)) |
| 286 | flags |= CC_CARRY; |
| 287 | } |
| 288 | } else { |
| 289 | /* Both operands are in registers. */ |
| 290 | if (fpa11->fType[Fn] == typeSingle |
| 291 | && fpa11->fType[Fm] == typeSingle) { |
| 292 | float32 rFm = fpa11->fpreg[Fm].fSingle; |
| 293 | float32 rFn = fpa11->fpreg[Fn].fSingle; |
| 294 | |
| 295 | if (float32_is_nan(rFn) |
| 296 | || float32_is_nan(rFm)) |
| 297 | goto unordered; |
| 298 | |
| 299 | if (n_flag) |
| 300 | rFm ^= 0x80000000; |
| 301 | |
| 302 | /* test for less than condition */ |
| 303 | if (float32_lt_nocheck(rFn, rFm)) |
| 304 | flags |= CC_NEGATIVE; |
| 305 | |
| 306 | /* test for equal condition */ |
| 307 | if (float32_eq_nocheck(rFn, rFm)) |
| 308 | flags |= CC_ZERO; |
| 309 | |
| 310 | /* test for greater than or equal condition */ |
| 311 | if (float32_lt_nocheck(rFm, rFn)) |
| 312 | flags |= CC_CARRY; |
| 313 | } else { |
| 314 | /* Promote 32-bit operand to 64 bits. */ |
| 315 | float64 rFm, rFn; |
| 316 | |
| 317 | rFm = (fpa11->fType[Fm] == typeSingle) ? |
| 318 | float32_to_float64(fpa11->fpreg[Fm].fSingle) |
| 319 | : fpa11->fpreg[Fm].fDouble; |
| 320 | |
| 321 | rFn = (fpa11->fType[Fn] == typeSingle) ? |
| 322 | float32_to_float64(fpa11->fpreg[Fn].fSingle) |
| 323 | : fpa11->fpreg[Fn].fDouble; |
| 324 | |
| 325 | if (float64_is_nan(rFn) |
| 326 | || float64_is_nan(rFm)) |
| 327 | goto unordered; |
| 328 | |
| 329 | if (n_flag) |
| 330 | rFm ^= 0x8000000000000000ULL; |
| 331 | |
| 332 | /* test for less than condition */ |
| 333 | if (float64_lt_nocheck(rFn, rFm)) |
| 334 | flags |= CC_NEGATIVE; |
| 335 | |
| 336 | /* test for equal condition */ |
| 337 | if (float64_eq_nocheck(rFn, rFm)) |
| 338 | flags |= CC_ZERO; |
| 339 | |
| 340 | /* test for greater than or equal condition */ |
| 341 | if (float64_lt_nocheck(rFm, rFn)) |
| 342 | flags |= CC_CARRY; |
| 343 | } |
| 344 | } |
| 345 | |
| 346 | #endif |
| 347 | |
| 348 | writeConditionCodes(flags); |
| 349 | |
| 350 | return 1; |
| 351 | |
| 352 | unordered: |
| 353 | /* ?? The FPA data sheet is pretty vague about this, in particular |
| 354 | about whether the non-E comparisons can ever raise exceptions. |
| 355 | This implementation is based on a combination of what it says in |
| 356 | the data sheet, observation of how the Acorn emulator actually |
| 357 | behaves (and how programs expect it to) and guesswork. */ |
| 358 | flags |= CC_OVERFLOW; |
| 359 | flags &= ~(CC_ZERO | CC_NEGATIVE); |
| 360 | |
| 361 | if (BIT_AC & readFPSR()) |
| 362 | flags |= CC_CARRY; |
| 363 | |
| 364 | if (e_flag) |
| 365 | float_raise(float_flag_invalid); |
| 366 | |
| 367 | writeConditionCodes(flags); |
| 368 | return 1; |
| 369 | } |